Smart UPS SUA750 completly dead, wont even power up. please help

[Anonymous user]

I bought a SUA750 about 2.5 years ago to protect my home theater projector. about 6 months ago or so (after a few brownouts) it started telling me the batteries needed replacing. I got busy and temporarily removed bypassed the UPS and pluged my projector directly into the wall with just a surge protector. I turned off the UPS and just left it there plugged in for 5-6 months. Now that i decided to finally replace the batteries, i went to power the thing up, and its completely dead. I get no response when i push the power button on the front of the unit. I am an electronics engineer so I'm not afraid to open the thing up and poke around inside. I did so and found that the mains power to the board looks fine, I followed the wires to see where they attached to the main pcb and then measured using a multimeter. The voltage looked fine at 120V. However the Battery voltage is very low like 2.5V or so. Any ideas at what to try next? Id rather not have to drop another 200-250$ on a new one when the thing isn't that old. Is there any fuses that could have broke (besides the overload protection, its between the cord and the pcb so it seems ok since i get voltage at the pcb)? I also checked the front buttons and verified that they work as they should.

Any help would be greatly appreciated.

[voidstar_apc]

Did you replace the battery with a charged battery? After 5 or 6 months, the existing one is almost certainly dead. Without the battery, it lacks the power needed to run the UPS.

[Anonymous user]

Next week at work i'll try hooking up the battery terminals to a DC power supply and try powering it up with out the AC plugged in. If that works then i trust that it is fine, and i just need new batteries. So can anyone verify that these units don't work at all without batteries/don't even power up at all even after being plugged in for a long time (over night). I thought that you could run them without batteries and they would just act as a surge suppressor/ power conditioner just fine?

[BillP]

i have tested this and an SUA750 should power up by itself without a good battery but the UPS would flash the replace battery LED at you telling you that the battery is not connected/isnt detected.

on the older Smart UPS, beginning with SU (such as SU700), they would show no sign of life at all besides the very first time you tried to turn it on. it would flash and beep quickly and thats it.

i believe that the UPS should at least beep at you/flash the replace battery LED. i will double check this in the morning when I can test it to be 100% sure.

any UPS that APC makes, in general, can be used without a battery but will beep/flash at you that the battery is missing. then, during a power outage of course, it will turn off.

i'll post back after testing it myself since i did that several months ago. i am second guessing myself after voidstar's reply.

[voidstar_apc]

I'm guessing the manual meant that the unit will continue to run while the battery is disconnected so that the battery can be replaced, not that it can start up without a battery. Especially since you've shown that it can't.

[tzobor_apc]

Hi, I have a SUA1500I that shows the exact same symptoms: after sitting unplugged for several months (it told me I had to replace the battery pack), the battery only has ~9V and the UPS doesn't power on, with or without the battery. I've read somewhere that some models don't power up without a battery but the manual says it should work if the battery is removed. Can anyone tell us if that is correct only if the UPS was running prior to the removal of the battery? Maybe models from different generations behave differently?
Please help!

PS: after reading this thread http://forums.isxusergroups.com/thread.jspa?threadID=1772&tstart=210 , I took my laptop AC adapter and charged the capacitors. It really did the trick! My SUA1500I powered on so now I have a reason to buy a new bat. pack!

Message was edited by: tzobor

[BillP]

Hopefully you get this.  Any chance you remember what you did to revive your UPS using the laptop AC adapter?  The website you referenced doesn't exist any longer so I can't see what was done and I think mine suffers from the same issue.

Thanks!

[Anonymous user · Accepted solution]

I believe what they mean is that they hooked up the DC voltage to where the batteries would usually be connected and the unit was able to turn on.

I just recycled a 750 unit that was completely non responsive and I put new batteries and it turned right on.

The existing batteries were at less than 1v and as a result caused the system to not turn on at all.

Luckily I have a pile of spare 12v batteries to test with.