abeln2672 wrote: ↑Mon Mar 02, 2020 4:35 pm
I noticed somebody lumped 32a level 2 charging in with DCFC as possibly harmful. Is there an actual consensus on this? I just bought a 2014 Rex, and while I don't plan to obsess over battery life, I'd obviously like it to last as long as possible. I installed a 32a charger at home because I do almost 40 miles on most days and more than that on some, so I wanted to ensure I'd have full juice everyday. With the battery buffer and BMS, I figured that was a non-issue. Incorrect?
I'd say, in order...
1. Don't worry about it.
2. Select "Reduced Rate" from your charging menu if you are worried about it.
I wouldn't lump L2 and DC together, but I'd agree that heat is the enemy of batteries. There used to be some general agreement in the battery community (ha! -- this is pre-EV, talking NiCAD RC airplane days when NiMH was new tech) that a 10 hour charge rate was deemed "safe" for battery health, but that was in the days of not very intelligent fast chargers that might monitor temperatures externally as a safety and taper the charge near the top.
Our EV batteries have plenty of head room so they're never fully topped off, and have advanced charge management systems, internal temp monitoring, and cooling systems.
But in the case of your 60Ah battery, you can go from empty to full in 3 hours with that 32A L2 charger, and you can recoup your 40 miles in just over an hour and a half.
There's an argument to be made for charging at a reduced rate if you have the luxury of time. It will reduce the cooling demands of the thermal management system, which itself is an electrical draw. And it certainly reduces the instantaneous load on your neighborhood's grid. Though I doubt either of these is a huge impact. Yet still... a three hour charge is a three hour charge, and there's going to be excess heat associated with that no matter how well it's managed. Detrimental? Probably yes to a small degree. Worth worrying about long term? I don't think any i3 owners have presented a compelling case against this.