UPS SLA Batteries: Old vs. New

For completeness, all of the surviving UPS sealed lead-acid batteries compared with a new battery:

They’re all discharged at 4 A, far higher than the nominal “20 hour” rate of 450 mA = 9 A·hr / 20 hr, but an order of magnitude closer to the rated UPS output of a few hundred watts which would call for a few tens of amps.

The new battery delivers 73 W·hr under those conditions, perhaps 50% more than the 50-ish W·hr from the used batteries, and with a much higher overall terminal voltage during the discharge.

Nothing unexpected, but now we know …