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View Full Version : VW e-Golf NOT using liquid cooled battery



podolefsky
05 April 2014, 1140
There has been plenty of talk about Leaf owners in Arizona having issues with their packs not lasting (the theory being it is due to high temperatures during charging). Apparently VW has tested their Panasonic NMC pack under these conditions and "The need for a cooling system wasn't there."

http://green.autoblog.com/2014/03/31/vw-e-golf-will-not-have-active-cooling-system-lithium-battery/#continued

Remains to be seen - one weird thing, I don't understand the statement about "lowest memory effect".

jonescg
05 April 2014, 1816
I've always felt that if your cells are getting hot during discharge, you're doing something wrong. Either make the pack bigger, reduce your power demands or get a better chemistry. But the need to actively cool a pack with anything more than ambient airflow suggests the sums aren't right.

podolefsky
05 April 2014, 1914
The issue with the Leaf packs was actually temperature during charging. The theory is that at elevated temperatures, like you would have in a warm state like Arizona, chemical reactions in the cells during charge shorten cell life. If you keep the cells cooler during charge they last longer.

Explained pretty well in this video. It's sort of hard to get your head around, since the "fix" is apparently to charge quickly so you have those reactions happening for less time. But high charge rates also reduce cycle life, so hard to say what's really going on.

I don't know how correct this idea is, but it seems to have some traction, which is why it's interesting that VW claims they're OK with air cooling.

https://www.youtube.com/watch?v=pxP0Cu00sZs&feature=youtu.be