How to test double conversion UPS with dead batteries

[V_King]

Hello,
Is there a way to test a double conversion UPS with dead batteries?
There was a 10KVA double conversion UPS being thrown away by our neighbours. They said it was working before they put it into storage. I though it would be great to try using it, because we have some conductive noise issues coming through mains, due to industrial machinery running in one of the units nearby.

BUT the batteries are dead in the UPS and when I power it up nothing is happening. Checked all the fuses everything is ok. I can only assume the main control board is powered from batteries? The batteries are 12VDC standard sealed stuff, but 26pcs are needed to get 312VDC required.

The unit is manufactured by Chloride Power Protection and there is very little info online.

[m k]

It's quite possible that battery voltage must be present before anything happens.
It's also possible that somewhere is a setting for use without batteries.

[SeanB]

No they need the batteries, as they power a small DC DC converter that powers the input rectifier and output circuits. The batteries also act as a large capacitor as well for the output side, and the ripple applied to them does contribute to the batteries failing. If the 7Ah SLA packs are not totally flat, charge them up for a few hours, and see if they recover, and then they will run it briefly. But you do need to replace all of them though, and probably also a good number of the wire jumpers with spade connectors that join them in series as well, as they will have corroded from being stored discharged.

[AndyBeez]

Makes sense the UPS runs off battery. I suggest the SLAs have long sulphated. An expensive and heavy fix. You can simulate the battery voltage on the PCB using a bench supply to see if the syscon powers on. But you will not be able the test under load. Are the batteries in series, parallel or a mix?

[Vovk_Z]

but 26pcs are needed to get 312VDC required.

312 VDC (possibly regulated?) isolated power supply may help instead of 26 batteries. But it is good if it has a current limit feature or any other current limiting part.

[fmashockie]

Speaking from experience testing/repairing much smaller UPSs, I would much prefer to simulate the battery(ies) using a DC power supply.  Without knowing the exact condition of the unit, hooking all those batteries up and powering it on could result in some dangerous amounts of current drawn if there's a short somewhere within the unit.  A DC power supply with current limiting as VovK_Z said would be your best bet for testing