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By Russ Finley on Sep 3, 2013 with 40 responses

Testing the Electric Car Battery Warranty Waters

Before the Chevy Volt (a plug-in hybrid) went on sale, Volt Chief Engineer Andrew Farah openly acknowledged that the extreme temperatures found in the Southwest have the potential to permanently reduce the battery pack’s capacity to store energy:

“The Volt may not be right for everyone. If you live in the Southwest, depending on how you use your car, the Volt might not be right for you.”

So what is a manufacturer to do if a given customer’s driving habits consistently exposes his or her battery pack to excessively high temperatures in a place like Tucson, or charges it five times a day, or maybe applies a blowtorch to it? As it turns out, the answer depends on what the warranty says, not so much on what the owner’s manual warns you not to do.

As the chief engineer for the Volt warned above, Nissan’s owner’s manual also warned that excessive exposure to ambient temperatures above 120 degrees F would degrade battery capacity. However, when a handful of Leaf owners in the Southwest realized that their batteries were losing capacity faster than batteries not repeatedly exposed to temperatures over 120 degrees F, they filed a class action lawsuit.

How Nissan responded:

 “So today, we are announcing that we are enhancing the warranty coverage of the battery system that powers the Nissan LEAF electric vehicle. With this action, Nissan becomes the first and only manufacturer in the automotive industry to provide limited warranty coverage for battery capacity loss for electric vehicles.

Under an expanded New Electric Vehicle Limited Warranty, Nissan will protect against capacity loss in LEAF batteries that fall below nine bars, of the available 12 bars displayed on the vehicle’s battery capacity gauge, for the first five years or 60,000 miles in the United States, whichever comes first. For LEAF vehicles whose batteries have fallen below nine bars during this period, Nissan will repair or replace the battery under warranty with a new or remanufactured battery to restore capacity at or above a minimum of nine bars.

A vehicle whose battery has nine remaining bars indicated on the gauge is retaining approximately 70 percent of its original battery capacity. This new limited warranty coverage remains subject to the other terms, conditions and exclusions of the Nissan New Electric Vehicle Limited Warranty, which otherwise remain unchanged.”

 How does the new Leaf warranty compare to the Volt warranty?

Nissan claimed that they were “..the first and only manufacturer in the automotive industry to provide limited warranty coverage for battery capacity loss for electric vehicles.” It’s possible the Volt was left off that list because it’s a plug-in hybrid as opposed to being a fully electric vehicle, or they left it off because it isn’t clear what the Volt battery warranty covers. At first glance, the Volt warranty also appears to guarantee 70 percent of battery capacity at the end of the warranty period except it makes that claim in the section of the warranty for component defects related to materials or workmanship:

This Voltec warranty covers repairs to correct any Voltec component defect related to materials or workmanship occurring during the 8 year or 100,000 miles (160 000 kilometers) term for the following:

The list of components following the statement “component defect related to materials or workmanship” includes: High Voltage Wiring, Voltec Control Modules, E-Compressor, Traction Power Inverter Module, Accessory Power Module, On-Board Charger …and, uh oh, the Propulsion Battery.

But all electric cars come with a warranty that covers component defects related to materials or workmanship. What those manufacturers didn’t cover (until Nissan’s announcement) is battery capacity loss if, as the Volt chief engineer said, ” …you live in the Southwest, depending on how you use your car… “

By placing the propulsion battery in that list of components covered for defects related to materials and workmanship, GM has muddled the answer to the question of whether or not a Volt battery degraded because ” …you live in the Southwest, depending on how you use your car… ”  is really covered for things like hot parking lots. Lawyers, where would we be without them?

The Volt warranty went into great detail about how they would fix or replace a battery …that is listed along with all of the other Voltec items covered for a defect related to materials or workmanship:

 “Like all batteries, the amount of energy that the high voltage “ propulsion ” battery can store will decrease with time and miles driven. Depending on us  e, the battery may degrade as little as 10% to as much as 30% of capacity over the warranty period. A dealer service technician will determine if the battery energy capacity (kWh storage) is within the proper limit, given the age and mileage of the vehicle. Typical tests can take up to 24 hours.

 Repair

 If possible, components will be repaired or replaced, and the original battery will be returned to the vehicle.

 Replace (If Necessary)

 Under warranty, the high voltage battery will be replaced with either a new or factory reconditioned high voltage battery with an energy capacity (kWh storage) level at or above that of the original battery prior to the failure. Your Volt battery warranty replacement may not return your vehicle as an “ as new ” condition, but it will make your Volt fully operational appropriate to its age and mileage.”

The Volt and  Electric Ford Focus  have an active battery thermal management system that cools the batteries in the same way that most car engines stay cool; by pumping antifreeze over the hot batteries to a radiator that is in turn cooled by a fan, however, the coolant pump and fan work only when the car is running. Not that it would do any good to leave the Volt running in a Tucson parking lot with a 140 degree surface temperature as some Volt enthusiasts discovered when investigating this issue:

“Since outside air temperature was hotter than battery coolant temperature this actually resulted in heating the battery …”

As if that were not an expected result. As mentioned by the Volt chief engineer, all lithium battery powered cars share this vulnerability to things like very hot parking lots.

From the Ford Focus Owner’s Manual:

 Battery: The best battery performance and life comes when the high voltage battery is at a moderate temperature.

 Indicator message: “It’s Hot Outside–Plug Vehicle in When Not in Use” displays when the ambient temperature is hot.

 Action: Plug in the vehicle to cool the high voltage battery for optimum performance.

 Indicator message: Severely Limited Performance Due to hot battery.

 Action: Displays when vehicle performance is severely affected by hot battery temperatures. Drive with caution. Keep vehicle plugged in when not in use to maintain proper battery temperature.

 The A/C system is used to cool both the interior of the vehicle and the high voltage battery. In hot outside temperatures, interior cooling may be temporarily reduced if the high voltage battery requires cooling. Keep the vehicle plugged in (when possible) to allow automatic battery cooling in high temperature conditions.

 If you drive in extremely hot climates: Note: It may be necessary to have an authorized Ford dealer decrease the coolant concentration to 40%. Note: A coolant concentration of 40% will provide improved overheat protection. Decreased coolant concentrations below 40% will decrease the corrosion/freeze protection characteristics of the coolant and may cause damage.

Bottom line, if your electric Ford Focus (or Volt for that matter) sits too long too often in hot Southwest parking lots, or if one of the dozens of the coolant system’s rubber hoses, or connectors, valves, or water pump fails or even if you have the wrong mix of water and coolant in your radiator your battery could get toasted and not be covered by the warranty.

 From the Ford Focus Warranty:

 The Lithium-ion battery (EV battery) will experience gradual capacity loss with time and use (similar to all lithium-ion batteries), which is considered normal wear and tear. Loss of battery capacity due to or resulting from gradual capacity loss is NOT covered under the New Vehicle Limited Warranty. See your Owner’s Manual for important tips on how to maximize the life and capacity of the Lithium-ion battery.

 From the Tesla Warranty:

 The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and use. Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT covered under this Battery Limited Warranty. See your owner documentation for important information on how to maximize the life and capacity of the Battery.

 Why was the Nissan Leaf the first to test the warranty waters?

  1. Somebody had to be the first.
  2. There are more Leafs out there than any other electric car (the Volt is a plug-in hybrid).
  3. The Leaf has a rather obvious indicator gauge that actually warns the owner that the battery can’t hold as much charge as it did when brand new (12 indication bars is full capacity, 9 bars is 75 percent). My Leaf is approaching 20,000 miles and the battery capacity gauge still shows all 12 bars. Why Nissan thought it was important to provide that information, I have no idea but it probably contributed to their being the first to deal with battery degradation not caused by workmanship or defects. To get that information on an electric Ford Focus requires a 24 hour test at the dealership.
  4. Some concerned Leaf owners found that there was nothing wrong with their battery after all. The gauge was simply miscalibrated.
  5. Another factor may have been that the Leaf owner’s manual actually quotes a not to exceed value of 120 degrees while most other manufacturers are more vague, never actually quoting a number. After reading their manuals, many owners in the Southwest were concerned by the fact that their car may have been exposed to temperatures higher than that.
  6. Range degradation would be much less noticeable with a plug-in hybrid where the engine simply takes over as is the case with the Volt.

 Active liquid-cooled thermal management verses passive air-cooled thermal management

Electric Ford Focus cooling system

The word “active” implies that the system uses moving parts like pumps, flowing liquids, fans, and valves. “Passive,” of course, implies no moving parts. Ultimately, both systems are air cooled but in the active system the heat has to be moved via a hot liquid to a radiator before the air can cool it, so the title could be shortened to “Active thermal management verses passive thermal management.”

The Leaf’s competitors have jumped on the bandwagon to make hay while its cooling system weathers the onslaught of various bloggers, conspiracy theorists,  and wiki authors by portraying that Rube Goldberg collection of parts in the video above that is their cooling system as if it is a good thing. If complexity is a good thing, the Volt, with its five radiators, wins, hands down.

A good place to start seeking evidence that the Leaf’s method of controlling battery temperatures  is inferior to a liquid thermal cooling system would be via battery warranties. But, as discussed above, until recently with the Nissan warranty, none of the manufacturers’ warranties cover owners for thermal damage quite simply because they can’t control everything consumers are wont to do, like leave a car in a Tucson parking lot.

Will the Leaf become the Prius of electric cars?

When the Prius first arrived its competitors claimed it was a money losing, unreliable, engineering farce that actually consumed more lifetime energy than a Hummer. We all know how that story ended.

At this point you may be wondering …”How does the Leaf keep its batteries from getting too hot without resorting to the pumps, coolant, radiators, hoses, valves, and fans (see  above photo)? As with the Prius and its unprecedented mileage, their solution is pure elegance. Instead of cooling batteries down, they don’t let them get hot enough to need active cooling. According to an interview in the Nissan Technology Magazine with Takeshi Miyamoto, (taking a deep breath …Engineering Director of EV Technology Development Division, EV Energy Development Department, Battery Engineering Group) the temperature is controlled by adjustment of the battery’s internal resistance. Of course, you can’t physically go inside a battery and alter its internal resistance but the internal resistance expressed is different depending on whether it is being discharged, or charged, and how fast that is happening, and at what temperature.

Translation: The computer controls battery internal resistance by varying performance parameters while letting battery temperature float up or down in a safe range. For example, I’ve noticed that my Leaf does not allow much, if any regenerative braking right after a fresh recharge. Regenerative braking does not return in full force until the batteries cool and/or discharge to a lower level. From the Leaf owners manual:

 Power Limitation Mode: This mode protects the health and operation of the vehicle’s Li-ion battery. This mode operates in certain extreme conditions (heat, cold, low state of charge). Power available to vehicle systems, including its traction motor, is limited resulting in limited performance, acceleration and top speed. Charging may be automatically terminated, especially with repeated quick charging in extreme hot weather.

Suppose you’re driving 80 mph up a mountain on a 120 degree day and the battery temperatures approach a level that could cause damage. The car’s software slows the car down (reduces power draw from the battery pack) as much as needed to keep the temperatures in a healthy range (and the car at a safe speed). If you are in stop and go traffic on a 120 degree day, if necessary, it will limit how fast your car can accelerate, and how much it can regenerate, etc, etc, to the point of shutting the car down in steps to prevent battery damage if necessary or if acceleration or top speed is too limited for further safe driving.

The car wouldn’t suddenly shut down. As with a low battery charge condition, it would begin by giving you warnings to get the car to a safe parking spot before finally going into Turtle mode, which will only allow the car to move maybe five miles per hour long enough to get to a safe spot. How often does a Leaf have to go into Turtle mode to protect the batteries? It must be a very rare event because I have yet to find with Google searches anyone who went into turtle mode because of high battery temperatures. On the other hand, as mentioned earlier, my Leaf’s computer often limits the car’s ability to use regenerative braking, in which range is traded off for speed and acceleration.

After reading parts of the Ford Focus owner’s manual, its obvious that they also have a limited ability to vary performance to control temperature. It has a warning indicator message that reads “Severely Limited Performance Due to hot battery” which means ” vehicle performance is severely affected by hot battery temperatures. Drive with caution. Keep vehicle plugged in when not in use to maintain proper battery temperature.” But that sounds more like an emergency measure as opposed to a design feature.

Simply put, the Nissan engineers have fine tuned their software, battery limits, and car performance in such a way as to not need a heavy, complex and expensive, active liquid cooling system. Leaf drivers rarely notice the performance changes happening to keep the battery pack from getting too hot. It is in some ways analogous to the fine tuned design of the Prius which remains unmatched for gas mileage performance after all these years. The consistent high ambient temps in the Southwest punched through the Leaf’s design envelope for a small number of drivers. They’ll get it under control, possibly with this new battery:

From Green Car Reports:

 Nissan is testing a revised lithium-ion cell chemistry for its Leaf electric car that the company says appears to be as durable in sustained extreme heat as its current battery is under normal conditions.

 If tests confirm that the new cells degrade at no more than the standard rate, even at high temperatures, the company hopes to have battery packs using those cells available next April.

 Those packs would become the replacement for any current Leaf batteries replaced under warranty for loss of capacity.

 Hayes said Nissan has thus far replaced only 22 batteries for capacity loss in extremely hot climates–less than 0.1 percent of the 31,200 Leafs sold in the U.S. through July.

I suspect that the Leaf may very well prove to be the Prius of the electric cars. The Leaf solution to controlling battery temperatures is actually technologically superior in just about every way to the primitive, ham-fisted system of hoses, pumps, fans, valves and radiators used in cars since the Model T … and in WW II era fighter planes I might add.

Every aircraft I have ever flown, or have ever been a passenger in, uses passive (requiring no moving components) air cooling for the engines (no fans, pumps, liquid coolant, hoses, or radiators), except one, a WW II era P-51 mustang fighter I once hitched a ride in. I had an old professor who had helped to design the system of shut off valves for that plane to prevent loss of coolant from bullet holes. Unlike the air cooled fighters and bombers, a single hole in the cooling system could bring a Mustang down.


Active liquid cooled P-51 mustang

Passive air cooled Skyraider over Vietnam

So, obviously, if  aircraft use passive air cooling, it must not only be adequate for cooling, it must also have some advantages over active liquid cooling systems in some applications. For commercial aircraft the two overarching reasons are:

  1. Less weight which translates into greater efficiency (the compact four passenger Volt weighs over 400 pounds more than a mid-sized five passenger Leaf, although not entirely due to its cooling system).
  2. Greater reliability via less complexity (fewer components like hoses, connectors, pumps, valves, and radiators to fail). The Volt has five radiators.

For the Leaf, you can add to that list, less cost.

In my life I have experienced dozens of instances in my cars or in the cars of people I know, of failures in the coolant system. One failure like that with a battery that relies on a pumped coolant is likely to permanently damage it, or at least to cause the computers to shut it down.

Note: This article was edited on Sept. 10 in order to provide clarifications that have been suggested by reader feedback.

  1. By Michael Walsh on September 3, 2013 at 2:04 pm

    With the LEAF battery now covered for capacity loss for only 5 years/60k and materials/workmanship for 8 years/100k. The question becomes: Is the (alleged) deterioration of polypropylene separators, because they haven’t been ceramic coated, a defect in materials? I’m inclined to say it is. But then I’m a LEAF owner in a relatively hot State. I’m sure Nissan would claim otherwise.

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    • By Russ Finley on September 3, 2013 at 8:49 pm

      Alleged deterioration? Are you starting an internet rumor or just passing one along?

      70-80 percent capacity after 5 years or 60k is what your Leaf owner’s manual told you to expect when you bought your car. Did you think Nissan was pulling your leg?

      Not sure what a relatively hot state is but the new warranty has you covered wherever you are. Most certainly if your rumor turns out to be true, the battery would be covered by the warranty.

      The Volt warranty appears to cover only workmanship and defects in materials. Now that Nissan has made the first move I suspect the others will eventually have to counter.

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      • By Michael Walsh on September 3, 2013 at 9:10 pm

        Polypropylene separators have been seen to shrink and/or deform in their natural state when subjected to high heat. Fact. This is why GM coated the Volt’s with ceramics. I’ve yet to see the insides of a non-coated Nissan cell, but I’ll lay odds that’s what’s happening.

        As to the capacity warranty, those in “real hot” states will most definitely benefit from it. But those of us in more clement climes (coastal LA, for example, where valley temps can easily exceed 100 degrees, but not for massively extended periods of time) will most likely get gipped under the capacity warranty, with our cars missing out by just months in many cases (which is probably why Nissan chose 5/60 to start with). And, BTW, four capacity bars missing – the threshold you need to meet to qualify for the capacity warranty – is 65.6% capacity remaining.

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        • By Russ Finley on September 3, 2013 at 10:06 pm

          And, BTW, four capacity bars missing – the threshold you need to meet to qualify for the capacity warranty – is 65.5% capacity remaining.

          Which is 100% more warranty coverage than the other cars are giving. Nissan says:

          Under an expanded New Electric Vehicle Limited Warranty, Nissan will protect against capacity loss in LEAF batteries that fall below nine bars, of the available 12 bars displayed on the vehicle’s battery capacity gauge.

          9/12= 75%

          Polypropylene separators have been seen to shrink and/or deform in their natural state when subjected to high heat. Fact.

          Facts require proof. Hard to believe Nissan would have missed that after all these years of developing their own battery.

          This is why GM coated the Volt’s with ceramics.

          A fair hypothesis. But ceramics are usually reserved for very high heat applications. Not warm batteries. Another hypothesis might be that the Volt battery is more susceptible to thermal runaway. A lithium fire is hot (and something to behold). The only thing that could stop a burning cell from turning the entire pack into an inferno would be something very heat resistant, like a ceramic. So maybe the ceramic is a sign of less stable battery chemistry or maybe just an extra precaution.

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          • By Michael Walsh on September 3, 2013 at 11:41 pm

            I’m not going to waste any more time on you, but you need to get one fact straight, and I suggest you call Nissan to verify it – you need to have 4 capacity bars missing NOT three. Call them and see if it’s not so.

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            • By jstack6 on September 4, 2013 at 5:05 pm

              All EV’s don’t REGEN when their batteries are 100% charged.

              Heat is the biggest factor on lithium battery degrading.

              Some chemistry of Li are better in the heat than others.

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            • By Russ Finley on September 4, 2013 at 11:46 pm

              “Some chemistry of Li are better in the heat than others…”

              You hit the nail on the head. One cornerstone of the conspiracy theorist arguments is that all Lithium based batteries have the same heat characteristics.

              .

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            • By Conspiracy Theorist on September 5, 2013 at 12:45 am

              Could you please enlighten us and share what the “conspiracy theorists” have missed?

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            • By Russ Finley on September 5, 2013 at 6:52 pm

              Here’s a good one …I recently read a comment on another website suggesting that car makers are deliberately making electric cars ugly so they won’t compete with their other models. You just can’t keep a good conspiracy theorist down ; )

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            • By Conspiracy Theorist on September 5, 2013 at 9:41 pm

              Yes, these theorists keep conspiring to make EVs better. Gasp!

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            • By Russ Finley on September 4, 2013 at 9:09 pm

              Goodbye…

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            • By Russ Finley on September 5, 2013 at 11:13 pm

              Well …maybe I don’t stand corrected. From Nissan when talking about the new $100/month battery lease/replacement program:

              All LEAF batteries installed under this program will enjoy coverage similar to the terms of standard battery coverage under the Nissan New Electric Vehicle Limited Warranty and be assured to maintain at least 9 bars capacity, or approximately 70 percent and protection from defects in materials or workmanship for the time they own their LEAF and remain in the battery program. If necessary, Nissan will replace the battery with a new or remanufactured battery to restore capacity at or above a minimum of 9 bars, much like the existing expanded battery capacity warranty.

              Lawyers, you got to love them.

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            • By Michael Walsh on September 6, 2013 at 7:26 am

              Your understanding is still wrong. I advise watching a few episodes of Sesame Street, which may help you understand how to count down from 12 to 8.

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          • By Randy on September 4, 2013 at 11:33 pm

            The bars on the leaf are not linear. There is a weird scale you have to find somewhere.

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            • By Russ Finley on September 4, 2013 at 11:55 pm

              Thanks, Randy. I have to admit, “below 9 bars” isn’t a real clear definition of battery capacity.

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            • By Conspiracy Theorist on September 5, 2013 at 12:12 am

              There are many things Russ needs to find, aside from the missing battery capacity gauge, including some basic knowledge of software engineering and electrochemistry. Some humility and human decency would be good too. If that’s not too much to ask.

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            • By Russ Finley on September 5, 2013 at 11:16 pm

              You sound an awful lot like a commenter I know and love who used to go by the name Kit P, and later, Not Kit P ; )

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  2. By G. Michael Murphy on September 3, 2013 at 6:08 pm

    Volt uses the cooling loop when plugged in to maintain proper battery temperature. It will actively cool the battery by engaging the AC to cool the battery. I have climbed into the car in 100-110 degree ambient air temperatures and have the ventilation system immediately blow cool air EVEN THOUGH THE AC is not turned on because the battery was being cooled.

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    • By Michael Walsh on September 3, 2013 at 6:36 pm

      You know, that’s very strange. We just brought a Volt home this weekend and I noticed this morning, when I first got in the car, that it was unusually cool in there while the outside air was warm and humid. Now I know why!

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  3. By Russ Finley on September 3, 2013 at 7:30 pm

    G. Michael Murphy said:

    Volt uses the cooling loop when plugged in to maintain proper battery temperature. It will actively cool the battery by engaging the AC to cool the battery. I have climbed into the car in 100-110 degree ambient air temperatures and have the ventilation system immediately blow cool air EVEN THOUGH THE AC is not turned on because the battery was being cooled.

    Michael Walsh said:

    You know, that’s very strange. We just brought a Volt home this weekend and I noticed this morning, when I first got in the car, that it was unusually cool in there while the outside air was warm and humid. Now I know why!

    I’ve read that the Mitsubishi MiEV also diverts the cold side output of the air-conditioner heat pump into the battery compartment when needed while plugged in and charging. However, your electric bill will be higher as a result because your wall outlet is powering the car’s air conditioner in addition to the charger.

    Neither the Volt or MiEV (or Leaf for that matter) use the air-conditioner heat pump to cool the battery compartment while driving. Why? You would have very little range if your car had to provide enough battery power to run a large refrigerator full of hot batteries.

    The Leaf slows or stops the charging if the battery pack starts to get too warm.

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  4. By JP White on September 3, 2013 at 9:51 pm

    If one uses the leaf battery app (android only) you’ll notice as you drive the battery temperature continues to rise. The software in the LEAF can’t cool the battery as described here. The further you drive the hotter it gets.

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    • By Bill on September 4, 2013 at 8:23 am

      Why use an Android app for that? The Left side of the instrument gauges shows battery temperature. Mine has never gone above 5 bars and that was when it was 102 outside. I am in the mid-Atlantic, not the desert, so not anywhere near the heat problem. Road heat is probably killing the battery in the SW as it is inches above the pavement. Don’t charge to 100% or use a quick charger if you don’t have to. I only charge to 80% on L2 and typically get 90 miles per charge. 70-75 miles if mostly on the freeway. The winter is when I lose about 10 miles, but that’s a temporary issue as opposed to hot places. I expect that by the time I’ll need to replace the battery (8-10 years), the cost will be less than $5000 and the replacement battery will hold at least twice what this one does now. At a savings of $10/day due to not having to buy gas, I’ll be able to pay for the replacement battery in 3 years with the savings.

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      • By JP White on September 4, 2013 at 8:33 am

        The reason to use an Android app is precision. The battery temp gauge may show no change, but the battery may increase 20-30F. The temp gauge is very imprecise. If you’ve never been above 5 bars then you clearly live in a temperate climate and your battery should age gracefully.

        For those of us in warmer climates our batteries are affected by the heat and I like to keep a close eye on it and see what causes a bigger temperature rise in the battery and avoid such behavior when possible.

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    • By Russ Finley on September 4, 2013 at 8:56 pm

      Hi JP,

      The software in the LEAF can’t cool the battery as described here.

      Could you cut and paste the part of my article that you think describes how the Leaf cools batteries? The Leaf system is 100% certified organic passive. Cooling is a function of ambient air temperatures. The Leaf system has a whole bag of tricks to prevent excessive temperatures, including turning the car off. Not included in that bag of tricks is an active cooling system.

      For the sake of discussion, let’s assume that Nissan has developed a heat resistant battery that can handle temperatures that are 100% higher than any temperature they will ever experience (a 100% margin of safety), in any climate. In this hypothetical scenario, you would probably agree that installing an active cooling system would be a waste. It isn’t needed.

      What an elegant solution that would be; a heat resistant battery instead of an active cooling system. Give that some thought.

      As it turns out, the center of the Leaf system is a heat resistant battery, one providing a much smaller margin of safety than the hypothetical one. If you doubt that, then explain the new battery under development that has an even better margin of safety than the current one.

      Nissan almost got there but less than a fraction of 1% of the Leafs in the U.S. exceeded that margin of safety. Nissan apparently was hoping that the warning in the user’s manual about temperatures would prevent that 1% from materializing. It didn’t, thus the warranty. But that warning makes it very apparent that Nissan was aware of the possibility thanks to all of the testing they did.

      Engineering can be complicated. You can’t just set a margin of safety. You first have to define boundaries of failure. Nissan chose as its boundary, 80% battery capacity after a given number of miles, or years. Every customer of course, assumes right off the bat that they will do better than that.

      Depending on air temperature, and how the car is being driven, the batteries may get hotter and hotter. But that is what they are designed to do. That is the Leaf system. When you said:

      The further you drive the hotter it gets.

      …you seem to be suggesting that this is a bad thing and that it is exceeding the margin of safety. You are assuming that because the batteries are getting hotter and hotter that they will eventually reach a temperature that would damage them.

      A smidgen of common sense would suggest that Nissan would take steps to prevent customers from burning up their batteries. Even the batteries on my power tools have a heat sensor to shut down the tool or charger if the batteries get too hot.

      One thing that will help protect your battery, depending on use and ambient temperature, is the Leaf’s range. The batteries can only get hotter and hotter until the car runs out of energy. Getting to a charger to continue the journey won’t work because the Leaf will stop charging if the batteries get too warm.

      Within in a given ambient temperature band, you can’t exceed your battery design limits by simply driving the car. You would need a blowtorch.

      The Leaf system (with the current Leaf battery) wouldn’t work on a pack as large as that found in a Tesla, which does have the range to cook batteries in many more scenarios, which would force the car to shut down before it reached the end of its tether.

      Is any of this starting to make sense yet?

      As you come down the mountain, say, after a day of snowboarding, your battery will not get hotter and hotter …presumably until it starts smoking. The software will limit regeneration to keep the battery temperature in an acceptable range. I suppose I can see how some will think I just said the Leaf cools the battery, but I didn’t.

      Certainly, when I come back from the airport, which is all downhill, my batteries would tend to cool, but they don’t because the software chooses to keep them warm while also charging the battery with regeneration. If they were approaching their upper temperature range, it would forgo the regeneration, letting them cool …passively.

      Point your Leaf up a mountain pass on a 110 degree day. Press the gas pedal to the floor and hold it there. The batteries will get hotter and hotter …until the Leaf decides to slow you down to keep them from exceeding a temperature that would damage the batteries. If, after slowing you to a safe speed they continue to get hotter, it will put you on the side of the road. If you are lucky, you will get to snow level first and cold air temperatures will allow passive cooling to keep pace with current flows, or at least allow the software to be less restrictive about current flow.

      Has your Leaf ever put you on the side of the road because the batteries got too hot? Didn’t think so. That’s because the batteries are designed to handle just about anything you can throw at them and if you finally do exceed design parameters, it will gently deposit you at the side of the road until the batteries cool…passively. I’ve yet to hear of this happening to anyone.

      Less than a fraction of a percent of all Leafs sold in the states have been impacted by high ambient air temperatures. The car can’t protect itself when sitting in a 140 degree parking lot any more than a Volt can.

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      • By JP White on September 4, 2013 at 11:06 pm

        The piece I refer to in your article goes as follows.

        “Simply put, the Nissan engineers have fine tuned their software, battery limits, and car performance in such a way as to not need a heavy, complex and expensive, active liquid cooling system. Leaf drivers rarely notice the performance changes happening to keep the battery pack cool. I’ve never noticed my battery temperature gauge moving at all.”

        The software or other passive systems employed cannot ‘keep the battery pack cool’ as you say. The more you drive the hotter it gets. Which is only a problem if it gets into a temp range that accelerates degradation. The *only* time I have ever seen the battery temp drop while driving is first thing in the morning; battery temp at startup 86F and ambient being 63F, it dropped 2 degrees F over the first 20 miles then started to rise again.

        The fact you have never seen your battery gauge move may mean you live in a climate that varies minmally, or you haven’t been behind the wheel as much as myself and others. I have seen it shift from 5 to 6 bars and 6 to 7 bars while driving on different occasions. I have also seen the number of bars go from 5 to 6 during a DC fast charge. The total range I’ve witnessed at start-up is 4 bars to 7 bars.
        Just because the battery gauge doesn’t move doesn’t mean the cars system is ‘keeping it cool’, you simply don’t see the temp variances since the gauge is very coarse.

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        • By Russ Finley on September 5, 2013 at 10:59 pm

          I appreciate the response.

          I can see how those sentences combined would suggest that the Leaf is somehow actively cooling the batteries, although they do not say how it is actively cooling them. I apologize for all the words you have spent because of my lack of diligence. See my previous response, which goes into great detail about how the Leaf system works, which should make this thread (based on a misinterpretation caused by me) moot.

          Your last sentence sums it up best, I think:

          Just because the battery gauge doesn’t move doesn’t mean the cars system is ‘keeping it cool’, you simply don’t see the temp variances since the gauge is very coarse.

          To prevent others from drawing the conclusion that I think you did, I will edit the article to strike the sentence where I mention that my temperature gauge is so stable (and footnote what was edited and why).

          I’ve seen too many disagreements that turned out to be a matter of semantics. Here are some perceptions that might be conveyed by the phrase “…keep the battery pack cool”:

          1) kept at a temperature lower than ambient …like beer : )
          2) kept from getting too hot
          3) kept at a constant temperature
          4) kept at ambient air temperatures

          If you can think of more, feel free to add them. I’m guessing that your choice is (#3) because you have repeatedly mentioned that your battery temperature tends to continue climbing on your driving missions, thinking that contradicts what I said they would do, which I didn’t mean to insinuate.

          The Leaf is not designed to hold a constant temperature. From the original article:

          … and the battery temperatures approach a level that could cause damage …to keep the temperatures in a healthy range …while letting battery temperature float up or down in a safe range.

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          • By JP White on September 6, 2013 at 11:01 pm

            We need to make a distinction between the cars systems keeping the battery safe, or keeping it healthy.

            Certainly if the battery gets very hot the car will progressively shutdown the car systems/power to protect the battery against severe damage. I believe that is the text you often quote regarding the safety mechanisms in place in the LEAF. No argument there.

            As for battery health, anything above 86F is not healthy for the LEAF battery and my experience shows that the LEAF makes no attempt to reduce power or employ any other ‘tricks’ when the battery goes above 86F. In fact it behaves normally with a battery a smidgen over 100F. There are no systems on the LEAF that are capable of keeping the battery healthy in hot conditions. That’s what active cooling is for.

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            • By Russ Finley on September 7, 2013 at 10:25 pm

              We need to make a distinction between the cars systems keeping the battery safe, or keeping it healthy.

              We need to start by defining “safe” and “healthy.” If your Leaf battery capacity does not drop below the warranty minimums, it has been kept “safe” from experiencing temperatures that would cause battery performance to drop below warranty minimums. It is therefore, by definition, “healthy” –meets warranty minimums. Less than a fraction of one percent of all Leafs sold in the U.S. have failed to meet that definition of “safe” and “healthy.”

              Certainly if the battery gets very hot the car will progressively shutdown the car systems/power to protect the battery against severe damage.

              Sure, you are describing that one part of the Leaf design that only deals with the rare case of an upper temperature limit being reached. Have you ever met anyone who had that happen? Can you explain how the Leaf system manages to make that such a rare event?

              As for battery health, anything above 86F is not healthy for the LEAF battery.

              If only it were that simple. Instances of battery temperatures above 86F are expected and part of the Leaf design. Again, to understand why, you have to start by pinning down the definition of healthy. A healthy battery is any battery that meets warranty minimums. Batteries that exceed warranty minimums just happen to be even healthier. How’s this radical idea working out for Nissan? Less than a fraction of one percent of all Leafs sold in the U.S. have failed to meet that definition of “healthy.”

              In fact it behaves normally with a battery a smidgen over 100F.

              I would hope so, because it is designed to behave normally (in a manner that keeps the battery healthy–meets warranty minimums) even when occasionally hitting that temperature. Did you mean to say that 100F is not hot enough to cause the car to go into turtle mode?

              There are no systems on the LEAF that are capable of keeping the battery healthy in hot conditions.

              The Leaf is one big integrated, holistic system working in concert. If your Leaf battery capacity does not drop below the warranty minimums, it has been kept, by definition, healthy. Even though it may be, for whatever reasons, incomprehensible to some, the Leaf system obviously works. Want proof? Less than a fraction of one percent of all Leafs sold in the U.S. have failed to meet that definition of “healthy.”

              That’s what active cooling is for.

              Active cooling is for designs that require it. Neither the Skyraider below or the Leaf require it. The Volt requires it, yet from the Volt chief engineer:

              “The Volt may not be right for everyone. If you live in the Southwest, depending on how you use your car, the Volt might not be right for you.”

              Active cooling on a 100F day won’t drop the Volt battery pack temperature below 100F (unless drawing power from the grid at a charging station). The Volt active cooling system won’t protect the Volt battery pack from 140F parking lot temperatures.

              Debate isn’t about convincing your debate partner. I never had any intention of doing that. Debate partners never cede. You can lead a horse to water and all that. Debate is to inform an audience.

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            • By JP White on September 8, 2013 at 4:45 pm

              Interesting hypothesis Russ regrading health and warranty minimums. The LEAF battery is unaware of the terms of the warranty, and the design of the LEAF’s ‘holistic system’ is also blissfully unaware of it. So why do I say that?

              The LEAF warranty minimums for capacity were establish well after the car first went on sale. I received my capacity warranty in writing just a few months ago. Prior to that I had the disclaimer I signed at time of purchase saying there is no capacity warranty for the LEAF. Nissan established the minimums ‘after the fact’ to assist those owners who are outliers in terms of rapid battery degradation. Not unreasonable and very welcome I might say.

              So prior to the warranty being established, by your definition there could be no healthy status determined for a LEAF battery, since health means exceeding warranty minimums. Linking warranty minimums to battery health is disingenuous given the order of events that took place before and after the LEAF went on sale.

              To further draw on the analogy, battery state below warranty minimums in my book would define an ill battery. More often than not it takes a period of unhealthy conditions to lead to illness. You’ll claim only a small percentage of LEAF’s have been ill enough for a battery transplant. True, but that doesn’t mean there aren’t a large number out there are unhealthy during times of hot weather. It’l just take time for them to fall ill.

              With any luck the new ‘hot battery’ Nissan are developing for potential release next year will raise the temperature at which battery degradation is kept at a reasonable ‘healthy’ level. If the LEAF system was working as well as you describe, Nissan would not need to alter the LEAF’s chemistry, and could instead focus on longer range.

              With the new ‘hot’ battery Nissan may finally be able to claim they have a EV Battery system that does not require active cooling and is happy with passive cooling. And this time they might be right.

              The 1.0 LEAF battery doesn’t quite live up to that standard and is degrading faster than anticipated for those in warm and hot climates. Active cooling would have been a great help to the 1.0 battery for some of us. When I wake up in the morning and my battery is 86F and its 63F outside, I know if I had active cooling the system would have chilled my battery overnight as it charged/sat idle. That cooler battery would take quite a while before it warmed up to 86F again.

              I will agree with you that active cooling is of little use while a car is parked unplugged in the hot sun, it would however be a great help while plugged in at night.

              Russ there is nothing wrong with a passive cooling design, as long as all components can tolerate the conditions. IMHO the 1.0 LEAF battery fell short of Nissan’s designs and goals. Sometimes do do just happens.

              Next go around they will hopefully fair better.

              As early adopters we understand going in we may buy a product that does have issues the manufacturer will fix in a subsequent model. The good news is that Nissan have confirmed that the new ‘hot battery’ will be compatible with 2011/12 LEAFs. Let’s hope they introduce it once testing is complete.

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        • By Russ Finley on September 9, 2013 at 9:01 pm

          Interesting hypothesis Russ regrading health and warranty minimums.

          That isn’t a hypothesis. To carry on the discussion we had to define what a healthy battery is.

          The LEAF battery is unaware of the terms of the warranty, and the design of the LEAF’s ‘holistic system’ is also blissfully unaware of it.

          I would hope so …the day the Leaf becomes aware …is the day I join Sarah Connor in the Mexican desert. I don’t recall ever using the word holistic until this post. But that word goes a long way to explain the Leaf system. From Nissan Technology Magazine:

          A safe and secure EV could only be created since its makers thought holistically, creating a car design that considers the entire vehicle: Not the battery technology by itself, but also a car body, motor and controls that work in tandem with the battery. That is why Nissan is pouring its energies into developing fully intuitive and integrated EV batteries.

          JP White continues:

          The LEAF warranty minimums for capacity were establish well after the car first went on sale.

          No they weren’t. Look at the bottom of this comment. That is the disclaimer you signed when you bought your Leaf. It closely approximates the warranty. The values you see in the disclaimer were set by Nissan based on testing and expected worst case conditions. The warranty only codified it. Unhealthy means falling short on either warranty or disclaimer minimums. I used the word “warranty” instead of “disclaimer” simply because the warranty now exists. I could go back and edit my comments to replace the word “warranty” with “warranty/disclaimer” …and if the warranty didn’t exist, I would have used “disclaimer” …same conclusions.

          I received my capacity warranty in writing just a few months ago.

          So did I, but that’s irrelevant. The disclaimer already defined a healthy battery. A guarantee of repair is a related but separate issue.

          Prior to that I had the disclaimer I signed at time of purchase saying there is no capacity warranty for the LEAF. Nissan established the minimums ‘after the fact’ to assist those owners who are outliers in terms of rapid battery degradation. Not unreasonable and very welcome I might say.

          Nissan established minimums with the disclaimer and later guaranteed to fix any car that fell below it with a warranty.

          The disclaimer established the minimums to expect. The warranty only guaranteed repair should your battery become unhealthy, as defined first by the disclaimer, and later by the warranty.

          So prior to the warranty being established, by your definition there could be no healthy status determined for a LEAF battery, since health means exceeding warranty minimums.

          Unhealthy means falling short on either warranty or disclaimer minimums. I used the word “warranty” instead of “disclaimer” simply because the warranty now exists. I could go back and edit my comments to replace the word “warranty” with “warranty/disclaimer” …same conclusions. The warranty and disclaimer both reflect Nissan testing and analysis for worst case scenarios.

          Linking warranty minimums to battery health is disingenuous given the order of events that took place before and after the LEAF went on sale.

          Not so disingenuous. I used the word “warranty” instead of “disclaimer” simply because the warranty now exists. I could go back and edit my comments to replace the word “warranty” with “warranty/disclaimer” …same conclusions.

          To further draw on the analogy, battery state below warranty minimums in my book would define an ill battery.

          I don’t follow. By definition, a battery below warranty/disclaimer minimums is an ill battery. One above warranty/disclaimer minimums, is a healthy battery.

          More often than not it takes a period of unhealthy conditions to lead to illness.

          The warranty/disclaimer both spell out that period.

          You’ll claim only a small percentage of LEAF’s have been ill enough for a battery transplant.

          I don’t “claim” anything. I quoted published percentages. Less than a fraction of a percent have fallen below minimums. More will fall, and be repaired. Nissan cut it very close.

          True, but that doesn’t mean there aren’t a large number out there are unhealthy during times of hot weather. It’l just take time for them to fall ill.

          I’m a little weary coming up with definitions for words like “large” and “healthy” just so this discussion can continue. Nobody knows how many “large” is and with the warranty, it is largely irrelevant. They will get repaired.

          If the LEAF system was working as well as you describe…

          There is a fairly precise measure of how well the Leaf system is working; less than a fraction of a percent have fallen below minimums. No need to resort to vague terms.

          Nissan would not need to alter the LEAF’s chemistry, and could instead focus on longer range.

          Nissan is altering the battery chemistry to take care of that fraction of a percent, which I think is a really smart move. What makes you think they are not capable of focusing on more than one parameter at a time?

          With the new ‘hot’ battery Nissan may finally be able to claim they have a EV Battery system that does not require active cooling and is happy with passive cooling. And this time they might be right.

          Their passive system is a fantastic design, but they cut the margin of safety a little too close for a fraction of a percent of Leafs that have failed to meet minimums and with the new chemistry, competitors are really in trouble. The Prius has never been matched. The Leaf could repeat the Prius success …or not. The future is real hard to predict.

          The 1.0 LEAF battery doesn’t quite live up to that standard and is degrading faster than anticipated for those in warm and hot climates.

          Nobody denies that some batteries are degrading faster than anticipated. Over 99 percent of the Leaf batteries far surpass the warranty/disclaimer minimums.

          Active cooling would have been a great help to the 1.0 battery for some of us.

          Again, vague words and terms. What exactly does “great help” mean? Longer battery life? That would saddle all other Leaf owners with that cost and complexity just to add some time and a few miles to the warranty/disclaimer for owners in extreme climates. You signed the disclaimer.

          If you live in the Southwest, your Leaf will probably still meet minimums. What really bothers some Leaf owners in the Southwest is the fact that Leaf owners in more temperate places will have significantly longer battery lives. That isn’t a good reason to lobby to saddle the other 99% with an active cooling system, especially with the new batteries on the way.

          When I wake up in the morning and my battery is 86F and its 63F outside, I know if I had active cooling the system would have chilled my battery overnight as it charged/sat idle. That cooler battery would take quite a while before it warmed up to 86F again.

          I will agree with you that active cooling is of little use while a car is parked unplugged in the hot sun, it would however be a great help while plugged in at night.

          But that isn’t the car you purchased. How do think that would sit with the other 99.9 percent of the Leaf owners who would be saddled with the cost, complexity, and reliability issues of a system they don’t need? Air condition your garage, if you don’t have a garage, build one, tarp your car and put an air-conditioner under it. Sheesh. Don’t ask the rest of us to pay so your car can have a longer battery life. You bought it, signed the waiver.

          IMHO the 1.0 LEAF battery fell short of Nissan’s designs and goals.

          It isn’t a matter of opinion. The design goal was described in the disclaimer. Only a fraction of a percent of Leafs fell short of those design goals, not the entire 1.0 Leaf battery fleet.

          Sometimes do do just happens.

          If by do do, you mean, a fraction of a percent of all Leafs failed to meet minimums, nobody denies that.

          As early adopters we understand going in we may buy a product that does have issues the manufacturer will fix in a subsequent model. The good news is that Nissan have confirmed that the new ‘hot battery’ will be compatible with 2011/12 LEAFs. Let’s hope they introduce it once testing is complete.

          Can’t argue with that.

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          • By JP White on September 9, 2013 at 11:46 pm

            The problem with the statement

            “Nobody denies that some batteries are degrading faster than anticipated. Over 99 percent of the Leaf batteries far surpass the warranty/disclaimer minimums.”

            Is that the warranty minimums describe a situation 5 years down the road. Most LEAF customers have had their cars for 2 years or less. The relatively small LEAF market in Pheonix is the canary in the mine for what is to come to other southern states in the US (and Hawaii). It seems clear to most that the LEAF battery won’t come close to lasting the 5 years at 80% in those states. Heck my battery is 18% degraded and its 2 years old.

            Stoaty’s battery aging model tries to make sense out of the data we do have from Nissan on the expected battery performance. Those in warm and hot climates are experiencing greater degradation than the model predicts.

            I’m of the opinion that the LEAF battery is on a steeper degradation trajectory than initially predicted for the southern states. IMHO it’s only a matter of time before more LEAF’s need replacement batteries across the leading LEAF markets in the southern states. Nissan’s decision to change the battery chemistry (and announce it prior to final release) is evidence enough for me that they acknowledge there is an issue that needs mitigation. They would hardly alter chemistry to deal with just 0.1% of car batteries. Cheaper just to replace them.

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            • By Russ Finley on September 11, 2013 at 9:34 pm

              Is that the warranty minimums describe a situation 5 years down the road.

              Five years or 60,000 miles. Drive your Leaf hard enough and you could hit 70% in the first year.

              Most LEAF customers have had their cars for 2 years or less. The relatively small LEAF market in Phoenix is the canary in the mine for what is to come to other southern states in the US (and Hawaii).

              You’re exaggerating. Southern states and Hawaii are warmer on average because of mild winters, not because of blazing hot summers. See chart below for problem children.

              It seems clear to most that the LEAF battery won’t come close to lasting the 5 years at 80% in those states. Heck my battery is 18% degraded and its 2 years old.

              Those states? What states? We don’t know how many miles your car has. If you continue to lose 9% a year you would be eligible for a battery repair sometime in your fourth year. Not all cars in your area are showing that much loss.

              Stoaty’s battery aging model tries to make sense out of the data we do have from Nissan on the expected battery performance. Those in warm and hot climates are experiencing greater degradation than the model predicts..

              Part of the problem here is the notoriety some individuals garner from the internet. The guy who started all this used to drive his Leaf up and down the California coast in an attempt to get the media’s attention. Some guy with an internet moniker of Stoaty has become famous trying to reverse engineer the Leaf battery performance.

              I’m of the opinion that the LEAF battery is on a steeper degradation trajectory than initially predicted for the southern states.

              I would reword that to say “I’m of the opinion that the LEAF battery is on a steeper degradation trajectory than initially predicted for the states with the highest number of days with temperatures capable of degrading the battery faster than predicted.” The term “Southern states” is a vague exaggeration.

              IMHO it’s only a matter of time before more LEAF’s need replacement batteries across the leading LEAF markets in the southern states.

              Recalls are common for all car makers, and can involve tens of thousands of cars.

              Nissan’s decision to change the battery chemistry (and announce it prior to final release) is evidence enough for me that they acknowledge there is an issue that needs mitigation.

              I’ve lost track of how many times I’ve had to squash that straw man, but the warranty is rather obvious evidence that Nissan is addressing the issue.

              They would hardly alter chemistry to deal with just 0.1% of car batteries. Cheaper just to replace them.

              … says the guy who thinks Nissan should put an active cooling system on all Leafs.

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  5. By Smurf100 on September 4, 2013 at 1:35 pm

    The battery cooling system in the Volt will run periodically when the Volt is turned off and parked in a hot parking lot if there is sufficient battery charge available.

    Only if the battery is used up are you at risk of excessive heat in hot parking lot….

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    • By Randy on September 4, 2013 at 11:25 pm

      It uses radiators, so unless you have a dark car, how does it work?

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    • By Russ Finley on September 4, 2013 at 11:27 pm

      According to the link in my article, what you just said isn’t true. My source could be wrong of course. It would bolster your case to provide a source of your own.

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  6. By Randy on September 5, 2013 at 9:46 am

    The best thing to do is get a Lead that is a light color and park the Leaf under a tree or in a garage. I had to order my Leaf just so I could get the silver one, for this reason.

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    • By Russ Finley on September 5, 2013 at 11:50 pm

      Good advice.

      From the link in my article, some more advice for Volt owners from the Volt enthusiasts who tested the Volt to see what happens when parked in a hot parking lot:

      The following steps would help mitigate battery temperatures on days where the predicted high is above 100F:

      1. Park in the shade.

      2. Use window shade screens.

      3. Plug in if possible.

      4. Perhaps do a remote start late in the afternoon. (Caution engine
      could come on). However, I would only do the remote start long enough to
      cool the battery and then discontinue remote start for reasons
      discussed above

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  7. By Bryan on September 5, 2013 at 7:09 pm

    Fine article Russ, Thank you. One question: Why do you keep insisting on calling the Volt a “plug-in hybrid”? There are plug in hybrids out there like the Prius, Accord, Porsche Panamera, et. al. The Volt operates like none of them, it does not fall back into “hybrid” mode once the electric drive range is depleted. When the battery is depleted the source of electricity to power the drive train transfers from stored electricity in the battery to electricity from the generator. Is there anything wrong with calling the Volt what it is, an “extended range electric vehicle”? Right or wrong, it IS a different animal altogether.

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    • By Russ Finley on September 7, 2013 at 3:52 pm

      Thanks, Bryan

      Let me start by saying that the Volt is the best car out there for the mission it was designed to do; emulate an electric car for roughly the number of miles the average driver will need in a day, then convert to a hybrid car until recharged from the grid. Ideal for an urban one car family, assuming they find the necessary engineering compromises acceptable (can afford it, and don’t put much priority on the capacity to seat five).

      Why do you keep insisting on calling the Volt a “plug-in hybrid”? The Volt operates like none of them, it does not fall back into “hybrid” mode once the electric drive range is depleted.

      It most certainly does go into hybrid mode. The gas engine fires up once the grid charge is consumed. That engine will turn on and off as you drive as needed, just like any Prius does. When the car does not need the gas engine, it shuts off to save gas. It comes back on again when the battery charge drops to the point that more energy from the gas tank is needed, much like any Prius does.

      The term “Extended Range Electric Vehicle” didn’t come from the Society of Automotive Engineers. In an attempt to differentiate their car from the Prius plug-in hybrid, GM marketing coined the term “Extended Range Electric Vehicle”:

      General Motors describes the Volt as an electric vehicle equipped with a “range extending” gasoline powered internal combustion engine (ICE) as a genset and therefore dubbed the Volt an “Extended Range Electric Vehicle” or E-REV

      We are all targets of marketing. No polar bear is ever going to hug a Leaf owner … ; )

      When the battery is depleted the source of electricity to power the drive train transfers from stored electricity in the battery to electricity from the generator.

      Once the grid charge is gone from the battery, all energy comes from the gas tank for both the Volt and the Prius-plug in. The electricity from regenerative braking is simply capturing a small portion of the energy imparted to the car by the gasoline. That’s just physics. The two main reasons why the Volt will use 30% more gas than the Prius while in hybrid mode is because it usually uses the gas motor to spin a generator to power an electric motor to turn the wheels instead of a mechanical linkage from the gas motor to the wheels (although the car actually does occasionally create a mechanical linkage to the wheels when extra torque is required), and because it weighs 600 pounds more than the Prius plug-in.

      Very little of the battery’s capacity to store energy is used after the grid charge is gone. If you could remove most of that battery and leave it in your garage after the grid charge is used up, you would actually get better gas mileage because your car would weigh many hundreds of pounds less but still have enough battery capacity to operate as a hybrid car. The regular Prius hybrid battery is a fraction of the size of the Volt battery. Proof that a car does not need a battery as big as the Volt’s to be a very efficient hybrid.

      Have you ever asked yourself why the Volt’s gas engine doesn’t rev up after the grid charge is gone (or before it is gone) to charge the battery all the way back up again? It is capable of doing that given time but the Volt engineers don’t want it to do that because gas mileage would plummet. Converting gasoline via an internal combustion engine into electricity and then storing what energy is left in a battery would be a horrifically inefficient way to put that grid charge back. If that were not so, there would be no reason to plug the car in for a charge.

      Right or wrong, it IS a different animal altogether.

      Not so different. It is essentiallya car version of a locomotive:

      A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors. No clutch is required.

      Before diesel engines came into widespread use, a similar system, using a petrol (gasoline) engine and called petrol-electric or gas-electric, was sometimes used.

      Diesel-electric systems are also used in submarines and surface ships and some land vehicles.

      In some high-efficiency applications, electrical energy may be stored in rechargeable batteries, in which case these vehicles can be considered as a class of hybrid electric vehicle.

      Instead of charging a battery when using regenerative braking, a locomotive dumps the electricity to giant resistance heaters located at the top of the engine where big fans blow the heat through a grid to the outside air.

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  8. By Johan Michal on September 28, 2013 at 2:27 am

    The key to knowing how much coverage you have or could have depends on the strength of the warranty you have.Make sure that you understand the auto warranty’s main coverage plans and use them to your benefits.

    http://www.pinterest.com/amtrustwarranty/amt-service-corp/

    [link]      
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