On 4/9/25 14:27, Gary Sparkes wrote:
Long term storage, of course, is different, but that's a much easier solved
problem, and design specs are often in the -30c to 25c range for optimal
capacity retention over long term storage. But operationally, 25-50c is
perfectly fine. Past ... above 5c, I think, you're looking at a 10% capacity
fluctuation in that 5c to 50c range.
Yes, most LFP batteries will work even at 60°C, but that does not mean
you should do it if you want to get the most out of your investment.
The biggest issue is battery aging, and keeping it within recommended
temperature values will ensure they last longer than if you don't.
While true, heat is the enemy of lithium batteries of any type, deep
discharging is the second worst enemy (BMS prevents actual cell damaging deep
discharge, but you really should never go below 30% of rated capacity if you
can ever help it - this is the most stressful zone), then charging too rapidly
- too high rate of charge.
The point of the BMS is to prevent you from operating your battery in
dangerous territory.
30% is not a reasonable floor to stop discharging a Li-Ion battery. All
you are doing there is limiting your available capacity. The recommended
floor to stick to is 20%. However, it is perfectly fine to go as low as
10% without any appreciable loss of overall capacity. And in an
emergency, you can even go to 5% and still maintain good long term capacity.
This is where Li-Ion outshines LA by a mile.
Limiting your capacity by not discharging to, at least, 20% SoC, is
quite pointless based on all the information we have so far, because
calendar aging is still going to get you either way.
Mark.
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