[remy_martian]

360W of heat is effectively going to a heatsink (the heater core), which heats the cabin. Seems puny in terms of delivered energy and 12V comes from a lossy DC-DC converter vs directly from the battery.

An interesting experiment would be to run them as a series string at 100V while they are immersed and there's coolant flow - should be around 3kW. The details of how to connect them on the negative pole are left to the reader...

 

[Tremelune]

The complexity in this thread is making my head spin.

My Leaf-powered Mini has a small coolant loop, and the pump failed months ago. I didn't even notice. The only time temps ever got over 60°C was when I was literally running up a mountain in the summer. My batteries don't get warm to the touch unless the cells are under 3.7V.

Granted, this is an 1800lb car, and the Leaf batteries don't get any of the coolant running through them, but I'm not light on the throttle, and it gets hot in Los Angeles. I would be very surprised if the stock radiator of an ICE car couldn't easily handle the heat output of an electric motor and its batteries for street driving. Like when my pump was working, I was using a Prius inverter radiator. Now the water isn't even forcibly flowing and it's okay.

I would run a single loop with a single pump and a single radiator: tank -> pump -> batteries -> inverter -> motor -> radiator (or really, whatever layout is simplest). If it proves inadequate, add complexity.

Batteries get hot from high-speed charging, and inverter/motors get hot from long high-speed runs (like minutes/hours on a highway). What am I ignorant of? Under what scenarios are other conversions overheating where mine is not?

PS - Getting rid of heater cores is one of the best things about ditching internal combustion...Heated seats go a long way, and a supplemental HV heater/defroster will take care of the rest...rapidly.

 

[asymptonic]

I think the complexity is battery warming. In LA you don't get low temperatures that often, so sluggish batteries probably doesn't come up often. Then, once you decide you need battery warming, you are trying to be efficient about the source of heat.

I think I agree about single radiator though, that was my initial plan. If the loops are completely independent you'd need more than one, but I think I'm okay with forgoing some modes in order to simplify that part.

 

[Tremelune]

My motor swiftly gets to maybe 35-40°C and then plateaus for the most part. Given that, and maybe an inline "T" thermostat to bypass the radiator, would normal driving get the battery up to "room temperature" in adequate time?

 

[remy_martian]

You also don't need a cabin heater in L.A. unless you go up to Mammoth regularly. But, yes, your loop makes total sense for modest charging rates.

Do you have regen and if so, what's the max "charge" rate you can absorb during braking?

 

[Tremelune]

Hard to say about the regen...I like a fairly strong regen for one-pedalin', but I know that it's significantly less than full throttle draw.

 

[57Chevy]

One thing to consider if recycling an ICE radiator is the dT is far less so there is no point having multiple rows of tubes/cores. The first core has the highest dT to the air, then any cores behind it are cooled by hot air and are next to useless. Big areas of single core with a shroud and ducting to eliminate reversion are the most efficient way of cooling electric. Also AC radiators are best kept separate as they'll heat the radiator make it useless. Tesla puts two AC radiators in the front fenders and one coolant radiator in the middle.