I agree. The cheap solar batteries in my shed have gone down to the point the BMS turned them off. So I added a second solar panel, then I added 3 more batteries in parallel. I just recently (with the help of my landscapers awesome shovel) moved the panels to a more optimal location and buried the DC cable to the shed. Now I never get lower than 70% SOC. I'm at 100% by 1pm on sunny days. It's a test off-grid system to power poe cams, smart bulbs, watch what wild animals try to eat my chickens etc. But really it is to see what location is best because I won't be cutting down trees I don't own, or don't want to. Going strong since 2013. Some of these batteries now have bluetooth, I added a bluetooth module on mine. BMS protects the cells, keeps them balanced etc, just to add to that. I couldn't find the video but Will Prowse on youtube has a solar powered gate opener operating for years, battery exposed to the elements in las vegas, going strong after years. I don't think I will ever buy a lead acid based battery again. On Thu, Apr 10, 2025 at 1:13 AM Mark Tinka via NANOG <nanog@lists.nanog.org> wrote:
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. _______________________________________________ NANOG mailing list
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