Originally Posted by booster
I think -4 is also the low temp damage temp the davydd had been told by ARV? That would also include storage that cold. Charging would still be at 32* cold side limit, I would think.
Note that it said expand their "pack" manufacturing capabilities, so it could, or could not, include making the cells that go in the packs.
-4F (-20C) comes from Elite Power Solutions LiFeP04 batteries as the low limit to prevent permanent damage whether in use or not. Only an outside the battery heat source can prevent that. That was new information that came out just a year ago and I don't think anyone was aware of it. Obviously the more advanced lithium battery boating industry was not about to be plowing the seas in those temperatures.
If anyone is making other claims I think I would be a bit leery about the information.
32F (0C) internal battery temperature will cause damage if you attempt to charge
at that temperature. More realistic is 35F for cutoff protection and Advanced RV keeps the optimal temperature above 42F (5C) Realistically with external heating, since the battery internal temperature in use is going to be well above ambient you most likely will not be camping in much colder. My experience is it has to get down to 20F or so before our external heat pads come on.
Upper temperature is rated at 145F and for longer battery life it is best to stay below about 110F or less. The only way to do so for us is to simply stay away from those temperatures and our philosophy to travel when and where air conditioning is seldom necessary the mission is accomplished. The Technomad people were the first to highlight this issue, but they encountered probably the most extreme situations possible and lost 25% battery capacity over 3-1/2 years when they reported it. Extremes like keeping batteries in an unconditioned oven like space sitting on asphalt over a 6 month summer period in Arizona. I doubt you could get much more abusive.
Our BMS controls all this. It doesn't control high temperatures. Charging will shut down automatically for cold temperatures. You can still draw off the batteries. So traveling in extreme cold temperatures with 800ah battery pack boondocked is achievable with a 10a draw for heating pads to keep battery temperatures above 42F assuming you travel or idle (second alternator) and recharge with regularity. We boondocked a week straight in a period where day and night temperatures were always below freezing mostly in the teens and down to 0F.