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Re: Weird AC behaviour while fast charging

Posted: Sat Aug 05, 2017 5:06 am
by pancello
That's interesting... The screenshots I took and posted above also indicate 7°C difference. Next time I use a DCQC I'll take some screenshots as well, or maybe even record the screen.

What I don't understand is why you say that from a longevity standpoint the pack should not have great differences between cells? I thought that although my battle should be against the warmer cells, having some very cold ones could only mean good...

Re: Weird AC behaviour while fast charging

Posted: Thu Aug 17, 2017 3:08 am
by rnlcarlov
I've had up to 12ºC diference in cell temperature. I had some cells near 42ºC and others at 20ºC. My A/C never stopped during AC, so it could be something more specific to the newer models (since both my C-zero and Malm's imiev are 2011 model year.)

pancello

Posted: Fri Aug 18, 2017 11:40 am
by pancello
It could be that the 14.5kwh battery models have this stop during charge. But I'm pretty confident my model is 16kwh... Is there anyway I can confirm which model is mine?

Re: Weird AC behaviour while fast charging

Posted: Tue Aug 22, 2017 2:52 am
by rnlcarlov
pancello wrote:It could be that the 14.5kwh battery models have this stop during charge. But I'm pretty confident my model is 16kwh... Is there anyway I can confirm which model is mine?


It's pretty easy. Just get Canion or EvBatMon running and check the pack voltage. The 14.5kwh have less cells so the voltage is around 300-320V (depending on SOC), which is lower than in 16kwh models (320-360V).

Re: Weird AC behaviour while fast charging

Posted: Wed Aug 23, 2017 7:54 am
by Aerowhatt
rnlcarlov wrote:I've had up to 12ºC diference in cell temperature. I had some cells near 42ºC and others at 20ºC. My A/C never stopped during AC, so it could be something more specific to the newer models (since both my C-zero and Malm's imiev are 2011 model year.)


We do know that they have changed the firmware along the way. Even updated some older models. There are even a few minor differences between mine and my wife's. They are the same model year built less than 60 days apart from each other!

Aerowhatt

Re: Weird AC behaviour while fast charging

Posted: Wed Aug 23, 2017 8:10 am
by Aerowhatt
pancello wrote:That's interesting... The screenshots I took and posted above also indicate 7°C difference. Next time I use a DCQC I'll take some screenshots as well, or maybe even record the screen.

What I don't understand is why you say that from a longevity standpoint the pack should not have great differences between cells? I thought that although my battle should be against the warmer cells, having some very cold ones could only mean good...


Since all the cells are seeing the same amperage and they behave and age differently based on temperature during fast charging. It does make some sense. I agree with you that fighting the warmest cells would make more sense. However since their warranty covers cell failures but not degradation. They are more motivated to keep the cells in the same thermal range during extreme events like fast charging. Less worried about overall degradation than developing cell disparities.

Having flown electric RC sport planes for years. I found that batteries charged at the field (at 2C rate) on ice lasted significantly longer than those at ambient temps. The Ice charging would cool the outer cells well but the center ones would still be hot. Batteries that were allowed to cool and equalize the cell temperatures before fast charging lasted far better than the other scenarios allowed for. All based on cycle life, not calendar life.

Aerowhatt

Re: Weird AC behaviour while fast charging

Posted: Thu Aug 24, 2017 6:07 pm
by pancello
Hi!

I just got canion back, and checked both temperatures during DC charging and volts. It seems my pack is really 16kwh, since they remain above 320V. So it really should have something to do with firmware updates and not the batteries versions...

About the temperatures, couldn't yet find anything conclusive since I didn't do a lot of DC charging, but it seems the AC comes off at 55%-56% no matter what. But at that point, the difference between cells is almost always above 6°C too. So... I think I have to do some more charges before getting a definite answer...

Thank you aerowhatt and rnlcarlov!