Ideal Charging Practices ?

[luebri]

Could have saved yourself some work, on the Mach-E forum they figured out that preconditioning was to 59 degrees, basically exactly what you came to.

a) I dont mind... its interesting and I'm a techie so it's fun. It takes about 5 minutes of "work" a day.

b) The target temp is a data point that has just gone along for the research ride. The primary research effort is to compare the difference in battery warming when doing certain level charges vs preconditioning.

… and well since you brought it up. I started this because there were some statements out there that incorrectly thought that battery charging does not have much effect on warming the battery....

And, if you think that charging is giving you any noticeable heat difference, that would also be wrong.

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[David Gervais]

Great work…. Thanks

 

[TaxmanHog]

Seasonal bump for all the newbies

 

[Firn]

I see this went the way of some excellent info on battery reconditioning, thanks.

Back to the original premis, the following reading is good as far as battery health.

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

Clif notes.
Depth of discharge/charge has an impact. Assuming you use 10% of the battery a day charging 10% daily will give you three times the lifespan of charging 20% every other day. Charging 40% every 4 days will give half the lifespan of charging 20% every two days.
*The info is not clear here if the consider "cycles" to be a 100% capacity cycle, which is the norm.

Sitting at 100% in high temps is very very detrimental. At 104 degrees 35% loss in capacity could be observed in a single year, vs 15% if kept at 40% SOC. At 77 degrees 40% soc would have a 4% loss, 100% soc would have 20% (note, the lightning does not charge to a true 100%)

Limiting max charge has an effect on lifespan with lower charge rates improving the longevity. Limiting max charge to 75% will double lifespan over charging to 100%.

Cycling 50% dod from 85% to 25% is better than cycling from 100% to 50%. The improvement was about 5% in lifespan at 2500 cycles if I read the graph correct.


☆ I make no claims to be an expert in the field, just recapping the info reported. Also, NMC has variying chemistry, I believe in general the results are similar for various chemistry but the exact details may be different.

 

[Jim Lewis]

Back to the original premis, the following reading is good as far as battery health.

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

I think the general precepts apply widely to Li-ion batteries. The exact numbers can probably vary a fair bunch depending on the exact Li-ion battery chemistry involved, as you mentioned in your conclusion. Battery University might not have the latest and greatest numbers applicable to the most modern EV batteries.

I overlooked this thread before, but I noticed a number of folks cited the manual as the authority on optimum battery charging practices, overlooking that the Ford PR department undoubtedly influences what goes into any Ford manual. Ford doesn't want the buyer to have range anxiety and feel restricted by the limits of battery chemistry. A main concern is happy buyers who won't kill the battery and be making expensive warranty claims. Darren Palmer, the EV VP, said their telemetry showed most owners were charging to 100% available capacity every day, and they wanted to encourage owners to charge to no more than 90% (available) capacity. Very likely, the 90% charge recommendation in the manual was mainly to discourage charging to 100%: https://www.f150lightningforum.com/forum/threads/top-battery-off-to-90-every-day.17738/post-357055.

Of course, we all know what makes it through the front office is the gospel truth. Just think about O-ring warnings in the 1986 Challenger shuttle space disaster...

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