I honestly don't remember where the 30C number came from and I haven't spent the effort to confirm the exact trigger threshold. I do know that from looking at the HV temperature sensors after a modest highway run the cooler doesn't come on below 30C. Numbers in the 20's, no AC and no physical indication of fan etc. Similarly, after extended highway runs I'm fairly sure that the cooler does come on because I've pulled the car into the garage and heard the non-cabin fan running while everything else was off, but the car was still 'on'. The noise profile is quite different.View attachment 31746
a: coolant loop
b: refrigeration loop
R101: Battery heater
A9/6: refrigeration compressor
Sadly, this diagram is missing the heat exchanger between the two loops. It sits in the battery coolant loop with the M43 pumps.
@Blaine: Where did you get those numbers for the activation threshold temperatures from? I've long been trying to find that information! The lower one is hard to observe, unless you want to spend the night outside in the dead of winter. I'm sure the upper one is wrong - I have never been able to observe the compressor turning on to cool the battery, and it frequently gets a bit above 30C in the summer.
That might just be the radiator fan - doesn't mean the refrigeration compressor is running. The compressor is in the back and makes a distinct whine, but you can only tell from outside the car. The radiator fan gas two speeds. Low comes on when stuck in traffic and the car feels it needs extra airflow. I've only ever hear high when I had an intermittent failure in the cooling system. High makes a pretty good impression of a fighterjet taking off.heard the non-cabin fan running
If you mean the AC-coolant heat exchanger and associated valving, there is one case it's definitely needed for: while using the 22kW fast charger over in Europe. That frequently makes the refrigeration system come on to cool the battery, but I haven't gotten any of the guys in the German group to record what temperature it happens at.Its hard to imagine that MB would have put all that extra coolant plumbing into the battery if they weren't going to use it to cool the system.
Great demonstration of the amazing efficiency of the electric drive train. All that heat the ICEs produce is pure waste!But also, our garage never got even remotely warm. It gets really warm and stuffy in the garage when we drive our ICE vehicles in this hot weather and then it has to shed all that heat.