# Cooling the batteries



## 67BGTEV (Nov 1, 2013)

Considering this 96V compressor. Any experience/feedback?


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## arklan (Dec 10, 2012)

I too want to keep my batteries at a good temperature
winter doesnt matter but in summer it can get to 60-70 degrees being reflected off the road
im gonna be parking it on the grass at work so the batteries dont cook while parked but during driving I want to make sure they dont die
was going to put some reflective foil at the bottom of the battery box to reflecy the heat back down
people usually pack the batteries in blocks so the ones in the middle get hotter and so discharge at a different rate to the outside ones
my box in the back can hold 30 cells so im hoing to leave the middle one out and hope it gives some ventilation

I was also thinking about having the cells sit in some coolant that would come up 2 thirds of the way up the side of the batteries and have a littke pump circulate through a radiator but have told that I cant do this

other than buying a little caravan fridge and rigging something up im at a loss


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## steven4601 (Nov 11, 2010)

You want to keep the battery pack cooler than the ambient air temp?


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## dougingraham (Jul 26, 2011)

67BGTEV said:


> Having driven the Leaf for 3 years with 50000 miles, i feel batteries need to be cooled, though nissan feels is not necessary.


The Nissan Leaf batteries are not LiFe and are probably on the edge for needing cooling. Most places and driving patterns don't need cooling. The Tesla batteries do need cooling but they are not the same kind of lithium as the Leaf batteries. From what I have read the only heat issue with the Leaf batteries is when charging. You don't want to charge when they are hot.

You can probably just arrange to turn on a fan for a period of time before you start charging and force cooler air through the battery pack. If you were able to do a 1C charge rate you would not see any significant heating of the cells. And only a Level 3 charger can do that. The built in one can't.




arklan said:


> I too want to keep my batteries at a good temperature
> winter doesnt matter but in summer it can get to 60-70 degrees being reflected off the road


I believe that we don't need cooling with LiFe type cells. I have been unable to get my cells to heat more than a few degrees above ambient in the summer and this is when pulling more than the 8C recommendation. My batteries are in insulated boxes and it still is not an issue. On the other hand I find that I need to warm my batteries in the winter. There was one study that was reported on EVTV that indicated LiFe batteries have longer cycle lives when operated at 40C than at cooler or warmer temps.


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## arklan (Dec 10, 2012)

dougingraham said:


> one study that was reported on EVTV that indicated LiFe batteries have longer cycle lives when operated at 40C than at cooler or warmer temps.


in summer it gets up to 45 some days
the heat coming off the road and pavement is well above that
if im sitting at the lights and cant move the heat coming off the road is going to be plenty more hot than 40 :/
im in perth western australia and its like florida or Mediterranean weather, maybe a bit hotter
winter is not a problem, it very rarely gets below 10 at night

about the leaf batteries I think if they need cooling, nissan would have already included
if not something would have been mentioned in the news section


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## bwjunkie (Jul 31, 2013)

How bout this...
If your boxes are metal, then you can build some *detachable cooling fins* that only get installed during summer? This pulls the box temp down towards ambient air temp?

josh


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## 67BGTEV (Nov 1, 2013)

Leaf Batteries are under the body, in a sealed steal box. In my MG, its under the hood, currently not in a box. Since batteries are closer to the Aluminum hood, I'm expecting higher temperature in the batteries. 
Currently, I'm planning to use the QC Port, which will be convenient for me to drive 100+ miles in a day. On a hot day, QC can increase the temp of the battery by 10F. Optimal temperature for Lithium Batteries is around 70F. I want to keep temp in Leaf Batteries in my MG under 75F.

Both Leaf and Volt have a similar chemistry of LiMn, but are different. Volt batteries, which are liquid cooled degraded slowly as compared to Leaf batteries, which don't have TMS. I've a strong feeling that lack of TMS in Leaf is one of the main reasons. In summer, when temp is above 75F, Leaf batteries hold the charge very inconsistently. 

Here are my plans:

I'm planning to get a close-to-air-tight PVC/polyolefin box - custom build
Blow cooled air and keep the battery temperature under 75F


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