How to properly check UPS?

Question

Uninterruptable power source

Hello. The situation is this: there is a UPS when there was a voltage drop, then the computers went out, how to check if the batteries died or not?
those. what is the sequence of actions?

Answer 1

1. Check if the battery is charged to the maximum.
2. Check (at least indirectly) the capacity of the battery.
To do this, you will have to organize access with the voltmeter probes to the battery terminals when the UPS is running (this is not difficult). A fully charged battery should have a voltage of 13.8 ... 14.4 volts without load (however, failure to reach this figure may be due to a malfunction not only of the battery, but also of the UPS charging part, then fiddling with the battery will not work). And as for the capacity, then indirectly - by a stable battery voltage under rated load - a drawdown of up to 11 ... 10.5 volts should stretch for several minutes under the load "computer + display", if faster - the battery is worse, the faster the drawdown .
You can check the capacity not only indirectly, but also measure it quite accurately, for this you need to connect a load with exactly known power consumption to the UPS instead of a computer (say, several marked incandescent lamps), and pre-charge the battery to the maximum. Let's take the final voltage of the battery as 10.5 volts, we will neglect the non-100% efficiency of the inverter. Then the total power of the load lamps (watts), divided by 12 volts, will give us the current drawn from the battery (amps). We measure the time during which the voltage drops under load to 10.5 volts, and multiply it by this current, we get the capacity (amp-hours). If it is less than the standard one by 40% or more, we change the battery.