I had to replace my UPSs a few weeks ago on short notice due to hardware failure, and I ended up getting a few LiFePO4 ones as a stopgap since they were on sale and I'd always wanted to try them. So far, so good. Curious if anyone else has switch to lithium UPSs from lead-acid and how that's going for you.
I have a big 20Ah, 48v e-bike battery that I've used with a sine-wave inverter for standby power, and it's a bit over 11 years old and going strong. So, as far as the batteries in these are concerned, I am cautiously optimistic that they'll last close to the 10 years they're advertised as. The electronics and inverter...we'll see, I guess.
Bonus question: While we're on the subject, has anybody tried those drop-in replacement 12V LiFePO4 batteries for regular UPS's? Supposedly, it says the BMS in them can work with the lead-acid chargers in UPSs and safely charge them, but I'm not sure I trust that.
I don't think so. Cheaper batteries have that problem, but a decent brand does not. Check out this one: https://www.powertechsystems.eu/home/products/48v-lithium-ion-battery-pack/48v-105ah-5-38kwh-lithium-ion-battery-pack-powerbrick/ I bought one for my house, and have a 5KW inverter connected to it. Its specifications say that can do 120A drain continuously. I have used it to boil my 3KW kettle a few times in one day (but not often - I usually use the power for other things), and it has been fine.
That's just a limitation of the product, not the technology.