bobkart wrote: ↑
Sun Feb 28, 2021 12:14 pm
SageBrush wrote: ↑
Sun Feb 28, 2021 6:37 am
-31F is the operating limit; 25F (-4C) is the lowest temp the LFP will charge.
I see . . . are those numbers for 'generic' LFP, or specific to the Ohmmu batteries? Because my understanding is that it's possible to tweak the chemistry to improve various generic chemistry characteristics (often at the expense of other characteristics). Discharge rate is one of those. Low-temperature charging may be another.
You can bet that Ohmmu buys generic cells and packages them.
Every time I read about LFP I come across the 25F charging restriction. While I doubt it is written in stone, for now it is pervasive.
I'm looking forward to learning how Tesla deals with the limit, now that they are putting LFP in the Model S and Model X. My 2¢ wager is that they added a way to heat the 12v case. The other possibility is that Tesla charges the 12v when the ambient is getting cold as a preventative step. That would work in my 'hood, but not in SK or Scandinavia.
LIke you, I have no idea why a smaller Ahr capacity battery solved Ohmmu's Tesla Model 3 problems. I asked, but was given a BS answer.
FWIW though, Tesla monitors the 12v battery in the Model 3 and 'knows' when it is EOL. It does not seem to me to be a far stretch guess that the LFP was confusing the Tesla diagnostics. It is beyond me though to say how or why.
I'm looking forward to seeing the 25F charge restriction solved, and for 12v LFP to drop in price with some competition and scale. For now the price approaches $1000 per kWh while cells are in the $100 per kWh range.