Joe_H wrote:You would need to find an UPS that is based on LiIon batteries, you can't just substitute as the charging circuitry is not compatible between the two.
Good deep discharge lead acid batteries will last longer than LiIon in recharge cycles.
You can. the charge/de-charge voltages of both are near identical.
plenty of car/motorcycle batteries that got hot-swapped with lithium batteries. Charge voltage of Li Ion =14.4V, that of Lead acid is 14.1V.
So there's no danger of over charging.
Lithium can sustain heavy loads better for longer. But once it drops far below 2,7V, it's output amperage is pretty much pudding.
10.8V,and the UPS would probably shut off, like it does with a lead acid battery.
While officially 2,8V is the cutoff voltage for cells, many people have gone much further (2,65V, and 2,5V even) and suffered no ill consequences trying to charge up the cells.
The added benefit of Li battery packs, is higher supported wattages. The readout (meter) will just stay on full (90+%) most of the time, until the battery is about to die. Then rapidly fall off, so the countdown timer might be off. But it works just fine.
The only thing is, with an 800/900W UPS, swapping to Li, I would be able to pull a 1000+W load. Once the power goes back on, the 1000+W load + whatever the UPS uses to charge the Li battery pack, might blow the fuse; as Li batteries can have high charge currents (charge much quicker than Lead Acid).