why i call Li fussy
Hi all, This doesn't cover all the concerns for me, but it does show at least some of them: https://youtu.be/_PgthByAYz4
Forum Discussion
FWC wrote:
The other thing to note, is that it really doesn't take that long or that much energy to heat the batteries.
The heat capacity of LiFePO4 is about 1000 J/KG/C meaning 1000 Joules of energy will raise the temperature of 1kg of battery 1C. A 100Ah LiFePO4 is about 15Kg, so to raise each battery 30C you would need 1000*15*30 = 450,000J. One Wh is 3,600J, so it would take 125Wh (ie 125W for an hour) to raise the temperature of the battery 30C.
Now that is per battery, but assume a decent sized bank of 600Ah, that is still only 750Wh. That is a standard electric space heater on low for 1 hour. Or it is 30A from your alternator for 2 hours. Or just using each battery to heat itself, it is only 15% of the battery capacity. Compared to heating the several tonnes of the RV up, this is trivial.
No info to compare different heating methods and "size" of heaters, but one of the low temp LFPs that uses the charger to heat it up first before charging starts has this info :
"Because it takes time to heat the cells, the charging process in below freezing temperatures will take a little longer. For example, with the low-temperature RELiON RB100-LT 100Ah battery, it takes about an hour to warm from -20°C to +5°C before charging begins. Over a smaller temperature range, heating to a safe charging temperature happens proportionately faster."
https://relionbattery.com/blog/lithium-battery-cold-weather
