Heating EV Batteries during winter
 

Hello.

The other day I pondered keeping EV batteries warm with substantial insulation and with water jackets underneath that insulation.

When it is cold, the water/antifreeze would be heated by a heating element in the water/antifreeze reservoir, and circulated over the insulated batteries.

During hot weather, the same system could circulate the water with the heating element off through a little radiator to keep the batteries cool?

What do you think?

IMO it really depends how much you're going to stress your batteries. The Tesla roadster uses liquid cooling/heating as does the Focus EV. The Leaf uses air cooling (and a battery warmer for cold weather). For DIY I'd probably go with air. Its just way easiser to do.

I've never had issue with my batteries being to warm, but to cold is an issue, for warming electric battery warmers are cheap, simple an fit in tighter spaces then a water jacket would, water jackets also tend to spring leaks if not done right, then you have a water leak in your battery box!
If you have lithium batteries and want to do a fast charge on them then you do need cooling but again this is best done with air, Nissan just moves air around in their sealed battery box so they don't have to worry about dirt or moisture.

I put a 2 inch box of foam around my lead acid pack for the winter and it's toasty. The car is used everyday and I actually have to leave the foam insulation open a bit because I can get over 100F after a few days of driving and charging.

This past week has been int the 30's and I just reinstalled my insulation pack and so far I am at 54F and climbing in my battery box.

Oh, that was interesting, and also helpful.

It depends on the batteries. Some get hotter in use, and/or they produce more heat just sitting there than others. Insulation is probably always a good idea in cold weather. The Leaf's battery is warmed while it is charging, so the energy comes from the wall; saving the battery for driving.