points by rcxdude 3 days ago | 0 comments
Lead acid batteries don't much like being cycled heavily. Even the ones explicitly designed for it (the average car battery is not) have about a tenth of the lifespan of lithium ion.
LiFePO4 is probably the chemistry best suited to it ATM. Lasts a long time, more stable, pretty cheap, and just a bit less energy density than other lithium ion options. Sodium-ion is looking promising but only just entering the market AFAIK.
[–] mnw21cam 2 days ago
[–] foobarian 2 days ago
It looks like sodium is another step change on top of LiFePO4. I look forward to see it scale
[–] ElevenLathe 3 days ago
Does this mean LA would be a feasible option for longer-cycle storage, IOW keeping a reserve topped up most of the year for those duldrums weeks with little solar or wind?
[–] rcxdude 3 days ago
I think it still loses out to lithium-ion on cost/kWh, and batteries in general are still a bit expensive for storage on the timescale of months.
[–] adgjlsfhk1 3 days ago
For long term storage, the right batteries don't exist yet (commercially). The good options are going to be one of sodium ion, flow batteries, or thermal batteries.
[–] Schiendelman 3 days ago
In addition to the fact that it doesn't really work better for that either, it's just not as safe as lithium iron phosphate.
A lead-acid battery mainly ages by cycle count. If you keep a decent quality battery charged up, and don't regularly discharge it too much, then there are claims they will last ten years. If you discharge them excessively each day, then you'll kill them really quickly.
A LiFePO4 battery has a quoted cycle count. But really what matters is simply elapsed time - the battery will last about ten years if it isn't abused, and you'll be hard-pressed to actually do that many cycles in that ten years. It ages mainly by elapsed time, not cycle count.
I used to argue that for an off-grid solar solution, you should get lead-acid batteries with capacity so that you are normally never discharging below 70%, and that this was still cheaper than getting LiFePO4 batteries with smaller capacity that you would discharge down to 20% each night. The lead-acid would then give you a larger reserve capacity for those instances where the weather is foul for a bit longer than normal and you don't get meaningful charging.
However, since then LiFePO4 batteries have continued to decrease in price, there are new Sodium batteries available now, and I haven't done the calculations again - the best option may have switched over, or it may be so close that it doesn't really matter which one you choose.