How warm do EV batterys get?

[Mouse]

I've got very little experience with lithium batteries of the size that are in cars and there's a lot said about keeping them at a stable temperate especially in respect to longevity and higher temperatures. I appreciate lower temperature is set by ambient temperature and the weather but I have no idea what sort of temperature rise is expected under low, moderate and high demand and when at low charge or rapid charging.

I have a BMW i3 94Ah battery which I am dismantling to repack the modules and it was fitted with a rather complex HVAC cooling system. I've got no way of reproducing this or modifying it and I'm left wondering if I'll do myself an injustice if I just scrap it and ignore battery temperature as a problem.

[johu]

I've never used battery cooling neither in Polo, nor in Touran. Not much experience with the latter. Polos LFP batteries gain temperature sortof quickly from 0 (or below) till 15°C then sit stable. No noticeable temperature rise when batteries are already warm.
That said, if you want to build a track car, you want battery cooling. If you plan to do a lot of fast charging, you want battery cooling. If you're just building a town runaround or medium distance cruiser, I'd say scrap it. WLTP test I think has 7kW (below 10 anyway) average power draw. Cruising at 90 draws 10-12kW average. So 600W heat dissipation over a rather large area.

[arber333]

I've never used battery cooling neither in Polo, nor in Touran. Not much experience with the latter.

Once i drove for 160km in one go, i left my car on EVSE L2 at 11kW charge and drove back home when it was full all in one go. I have LiPo cells and they were quite warm, like 40 degrees when i arrived home. When at home i connected at some 5kW only and temperature subsided.
I think the strain of highway driving, fast charging and then driving without cooling down first made most of the heat stay in battery.

There was never any noticble change because of that, aside of me being more carefull when planning my trips.
I think what is really more important is to uniformly warm up batteries for charging when below 0deg ambient. You want to have your EV indoors!

[Kevin Sharpe]

Lots temperature data here for the Nissan Leaf pack on a road trip;