SageBrush said:
@DaveinOly, please clarify the effects you read about re: SoC and temperature.
I know that temperature causes a proportional change to internal resistance. What else ?
nothing but what we already know. High SOC and temps don't mix. We all wonder why Nissan had so much confidence in a battery chemistry that failed so miserably but it was the testing process that misled them.
Nissan took a pack, cycled it 500 times over the course of a month at 60ºC which as we know makes Phoenix seem like Alaska and it came out with less than 10% degradation.
the cycling was supposed to represent two years of average driving but as we all know that didn't work out when reality was added so what went wrong?
Testing shows that its not the high temps but the combination of time and high temps. The cycling was done so fast (charged at 1.5 C, discharged at 2.5 C and repeated in roughly 80 min cycles) that time at high SOC and the issues that would create was minimized despite the crazy high temps that existed for the entire month of testing.
The other thing that came out of the testing was that cycling was a VERY small player in the degradation process. It exists but to a much smaller degree. This is why we have 100,000 mile LEAFs with one or no bars missing. Its because they piled on the miles very quickly which means time at high SOC was simply not possible because to get that kind of mileage, the car was not sitting overnight, it was pretty much being used very soon after the charging was done.
So what we have here is our previous beliefs that multiple fast charges in the noon day Sun was killing our packs and shouldn't be done when the reality was the real killer is the fully charged LEAF sitting in a garage in temps as low as the 80's and 90's
But my experiments (yeah those AGAIN) has "so far" proven otherwise. It would appear that it doesn't really matter how hot the pack gets as long as you drive it right away (adding more heat btw...) reducing the SOC meaning that temps do play a part but only in certain situations. If you have been following my blog you would know I have done everything I possibly can to create and enhance heat related degradation besides moving to the desert and the results? Scroll up to see my latest battery stats.
so my take?
finish charging as close to your departure time as you can and don't charge to 100% if your one way destination does not drop you to 80% SOC or lower.
Don't charge at work on L2 AT ALL if you do not absolutely need it to make it home and even then, I would still recommend you stopping on the way home for a 15 min QC instead. Reasons are L2 is too slow and its simply a few hours at high SOC during the hottest part of the day.
This I have come to believe is THE NUMBER ONE SOURCE OF DEGRADATION for many of the people here.
**edit** sorry, this is not post I put battery stats in... I guess its somewhere else here?
