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.