testing DLA1500RM2U without battery

[Anonymous user]

Hi,

I have an old DLA1500RM2U UPS. Most of the batteries had swollen, are dry now, and don't seem to build up or hold charges. I removed the battery pack.

When I plug in the UPS into mains, I don't see any LEDs coming on. Not in front panel, not in back panel. However, when I opened the cover without connecting the earth, I saw the 'site wiring fault" red LED coming on. And I could check that the incoming, and several points near the incoming, have 122VAC.

But the connectors that go to the primary side of the main (big) transformer doesn't show any voltage. So the transformer secondary side, or the connectors to batteries, or the AC output sockets in the back panel, do not show any voltage either. I am trying to determine whether it is worth buying batteries, or whether this thing is already a toast.

Is there a way to bypass the "battery required to start UPS" thing? For example, can I supply the board with 12V through some connectors, to bring the control circuit up? The board says "main pcb 3.6G smart ups" and "640 7732H rev 9".

[MarkC_apc]

I'm quite sure this is a 24 volt DC UPS.  If you can put 2-12 volt batteries in series and connect properly, you could check when on DC voltage.  I believe stock batteries are 7.5 amp hour and takes four - two series/two parallel, so you would need similar totals of AH - 30 amp hours at 12 volts (maybe more).  Do not reverse polarity or you WILL have a "toast" unit.

[Anonymous user · Accepted solution]

Thanks... it is indeed a 24V supply. Is there any way I can tell if the unit is operable, from checking the circuit board alone?

I am wondering whether I can test functionality if I connect any size batteries of 2 x 12V. (1.3 AH or any capacity, I guess it doesn't matter how long they hold charges, as long as it brings up the UPS online.) If I know that it is usable, I can go buy batteries. I wish there are local shops who keep some batteries for testing purpose, but the local battery shop does not have any batteries available for such testing.