# Battery packs and Heat - Nissan Leaf AZ experience



## Ziggythewiz (May 16, 2010)

a) yes, none, no
LiFePO4 has better heat tolerance than most other batteries.

The Leaf probably runs the AC through the battery pack when necessary. Natural forced air means there's just a fan circulating ambient air.

3 years should concern you if you want it to last longer than that.


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## Kamleshgk (May 24, 2012)

Ziggythewiz said:


> a) yes, none, no
> LiFePO4 has better heat tolerance than most other batteries.
> 
> The Leaf probably runs the AC through the battery pack when necessary. Natural forced air means there's just a fan circulating ambient air.
> ...


Thanx for the reply.
3 years warranty is a problem when the global average is at least 5 years.


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## MN Driver (Sep 29, 2009)

Ziggythewiz said:


> The Leaf probably runs the AC through the battery pack when necessary. Natural forced air means there's just a fan circulating ambient air.


The Leaf has zero active battery cooling. There is no air intake or exhaust through the battery pack either from air internal to the car or from the outside of the car through the battery pack. They essentially rely on the temperature the case of the pack is exposed to in order to cool it. IMHO a terrible design for LiMn chemistry when sold in a place like Phoenix where the pavement can fry an egg.


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## MN Driver (Sep 29, 2009)

To the original poster, I'd wait until that car has been released for 3 years and then ask owners in the hottest part of India if their pack has seen degradation. I think patience is important for this, as proven by the issues Nissan has encountered. Natural forced air cooling could be air from outside the car or air from inside the car. Both have their advantages and disadvantages. If outside air is pulled in, it will be the temperature of the outside. If inside temperatures are pulled in, it will be the temperature of the car as it is baking in the sun until you get the air conditioning going(if equipped) and then the battery will then have cooler air going through it as you drive.


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## Kamleshgk (May 24, 2012)

MN Driver said:


> To the original poster, I'd wait until that car has been released for 3 years and then ask owners in the hottest part of India if their pack has seen degradation. I think patience is important for this, as proven by the issues Nissan has encountered. Natural forced air cooling could be air from outside the car or air from inside the car. Both have their advantages and disadvantages. If outside air is pulled in, it will be the temperature of the outside. If inside temperatures are pulled in, it will be the temperature of the car as it is baking in the sun until you get the air conditioning going(if equipped) and then the battery will then have cooler air going through it as you drive.


Thatz an important point raised. 
This image of the e20 design can offer some clues?









As shown in the above image, You can see the battery cooling air duct. Is this inside air or outside air?
For me the air to cool the battery pack, seems to be coming from the AC compressor so it should be cool air, right?


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## TonyWilliams (Apr 23, 2013)

All the best battery packs in the world are currently liquid cooled. The Tesla Roadster now has over 5 years of service in places like Phoenix with no heat related issues. The Volt battery is very conservative, with good thermal insulation, active liquid cooling, and only 20% - 80% SOC used.

The LEAF, on the other hand, has no active cooling whatsoever (not even an internal circulation fan that the prototypes had), and also uses 2% - 95% SOC. In addition, even though the LMO chemistry has a relatively low susceptibility to combust, it is quite susceptible to heat induced accelerated degradation.


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## Red Neck (Feb 1, 2013)

Mine on my mini electric car isn't  Sinopoly prismatics do not really appear to have much issue (yet anyway) at 25C at currents of up to 380A..
I don't really see it as a major issue for prismatic cells, if they are in an open case or if a duct for at least some air changing..

For LiMn and cylindrical cells, cooling is a must. For prismatics, not really.


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