homelab

This is the $10k solution to the $100 problem I was looking for, thank you for the idea.

"My dear significant other, the server's battery backup is dying -- I'll be on the roof."

I second this idea, if it's feasible. As noted elsewhere in this thread, the lead-acid batteries in UPS units have a limited lifespan, even if not regularly drained. Solar and off-grid enthusiasts have determined that parity between overall lifetime cost of lead-acid versus lithium batteries was reached years ago, and now it's firmly in lithium's favor, mostly due to the greater number of recharge cycles.

Contraindications for lithium batteries would include:

• high local costs for lithium battery packs
• lack of space for the hybrid inverter, as they're usually not rack-mountable
• the homelab drops below 0 C (32 F), in the specific case of LiFePO4 cells

That said, breathing life into old equipment is usually more environmentally friendly than acquiring new equipment.

The primary concern is switchover time. A purpose-built UPS can switch in about 10 microseconds. Those large "solar generator" battery packs switch in about 30 microseconds. That might be fast enough, but it's not guaranteed to be fast enough like a UPS is.