Are lithium batteries worth the cost?
I can carry two group 29s in my AF1150. Are they worth it?
Forum Discussion
I think the actual test data in the paper is probably more telling. There they charge/discharge LiFePO4 cells at 1C, 1000 times at various temperatures. Even after brutal test like this, the battery that was cycled at -5C had only slightly worse degradation than the room temperature batteries. To me that makes it pretty clear that an occasional charge cycle at -5C (or even lower) at a less than 1C rate of charge is not something to be worried about. Cycling at very high temperatures was actually far worse for the battery.
It is up to the user to decide what their requirements are, but for my use I am never going to need 2000+ 100% DOD cycles out of my batteries. In a good year, I am at about 100 nights of use, and most of those are at < 50% DOD, so even if I only get 20% of the rated cycles from my LiFePO4 battery, it will outlast my use. So in my case I don't sweat charging at -10C.
Now if this was an EV where the goal was to have a 200,000 mile lifetime, then the calculus would be different.
I think the most important thing to realize is that there are no black and white rules or limits. You can charge below freezing, you can run down to 0% SOC, you can cycle at high temperatures, it is all a trade off between usability and lifetime.
It is up to the user to decide what their requirements are, but for my use I am never going to need 2000+ 100% DOD cycles out of my batteries. In a good year, I am at about 100 nights of use, and most of those are at < 50% DOD, so even if I only get 20% of the rated cycles from my LiFePO4 battery, it will outlast my use. So in my case I don't sweat charging at -10C.
Now if this was an EV where the goal was to have a 200,000 mile lifetime, then the calculus would be different.
I think the most important thing to realize is that there are no black and white rules or limits. You can charge below freezing, you can run down to 0% SOC, you can cycle at high temperatures, it is all a trade off between usability and lifetime.
