richms:

 

Place I know of will just replace the lead acid UPS batteries after any reasonable outage because they seem to be a 1 or 2 shot type thing. On the subsequent outages they would die without warning at a very short runtime.

 

If they are just holding over for a generator to start then fine, but using the lead acid batteries capacity down to near zero seems to be the end of them.

 

Bring on the lithium ones.

 

When dimensioning their UPS systems, people often make the mistake of misinterpreting the manufacturer's specifications. A 1600VA UPS can withstand a load of 1600W for approx. 11-12 minutes, after which the batteries are completely discharged – something that should be avoided.

Eaton has discharge curves for its UPS systems, which are a little difficult to find, but once you have them, you can quickly see that much lower loads should be expected. My two (soon to be three) UPS units are purely safety UPS units whose sole task is to ensure the safe shutdown of the servers after 15 minutes. This is controlled by a Raspberry Pi, which has full control over the UPS via USB. To do this, it also queries the internal measurement data via USB. Occasionally, it also tests via (small!) partial discharge whether the capacity of the batteries is still sufficient (and not that an outdated battery appears to be OK, but then collapses under load).

As already mentioned, normal batteries need to be replaced after 2-3 years, and those with extended capacity after 4-5 years – assuming that they are not kept at temperatures higher than 24°C (which some people in the rack do not always take into account; the cooler, the better for the service life).