Voltage while on battery is only 93v,is that normal?

[Anonymous user]

The UPS is a BR1500.I have a true RMS multimeter that I used to measure that.I have also the BR24BP attached to the UPS,and this voltage was measured while both external and internal batteries were full and I unplugged it out of the outlet just to test that.Isn't that too low?All the equipaments I have attached to it works with no apparent problem,but I'm afraid that this might be an issue for some types of products that I could need to use on the UPS in the future.

[Anonymous user]

Looks like someone didn't read my post 😛

Message was edited by: GamerBR

Message was edited by: GamerBR

[Anonymous user]

Unless you use a TRUE RMS multimeter, the measuraments made by the multimeter will be wrong.

The output wave of your UPS is a rectangular shaped type of wave aka stepped approximation to a sinewave. Cheap multimeters can't measure this kind of wave correctly.

[Anonymous user]

Yeah, I confess I jumped into conclusions after reading the subject only. Sorry, I don' know what's going on with your UPS, it should be reading 115V +/- 10%.

Are you from Brazil? I am too. 🙂

[Anonymous user]

Yes,I'm from Brazil too.
Just adding an info,the 93v test was while it had only a really small load into it(~15W),so I tried to plug more stuff on it to see if it would be the same voltage,at ~300W it is even worse,it went down by a little amount(92V).

[Anonymous user]

It's not normal these readings, but most power supplies can work at 90V or even less sometimes.

Have you tried measuring the output with another multimeter? Maybe your multimeter is not functioning correctly when measuring rectangular shapped waves for some reason.

A think one defective battery could also be the problem. Since your UPS runs off 24V battery bank, two 12V batteries in series to create one 24V bank, so perhaps one battery is failing, lowering the DC voltage output, but I think this is unlikely without some kind of warning from the UPS anyways. Maybe your unit has some kind of defect on the inverter output voltage regulation. I think the best thing you should do is to send your unit back to APC so they can check what's going on.

If the warranty has expired, these guys are authorized and trained by APC at the APC brazilian factory, to fix APC's upses:

http://www.csolutions.com.br/

[Anonymous user]

The other multimeter I have isn't true RMS,so the reading`s cannot be trusted,anyway it's giving a bit lower voltage comparing to the other,like 3 or 4V less.
About the batteries,I tried running while on only of the banks of battery,same voltage on both,so the batteries are not the problem.
About the warranty,APC warranty in Brazil is 2 years right?My apc is a bit less than that,but I [almost for sure] voided my warranty by modding the battery connector to plug in a battery desulfator on it(the problem is not from it,I tried it with it disconnected and the voltage stills the same,and just after buying the UPS I did the same tests and the voltage were already lower than 100V,it's just that only now I started bothering about it).
I don't feel like paying to fix an UPS that's working for my needs and I'm a DIY person,I would prefer fixing it by myself 😛

[Anonymous user]

Well, I think you might have voided the warranty by doing what you did, so you have two options. Check all the internal stages responsible for producing AC power locally or have someone do it for you.

[BillP · Accepted solution]

How was this problem discovered? Did the UPS previously work properly? You say that all your equipment works properly. It is HIGHLY likely that your "true-RMS" multimeter is in fact, NOT True-RMS. This is very likely given that the reading between your two multimeters are very similar, which would make perfect sense given they are both NON-true RMS.

So are simple devices, such as an incandescent light bulb, not working properly while the UPS is operating on-battery? Of course, a light bulb will go very dim when the UPS goes on-battery if what you are saying is true about the voltage dropping to near 90vAC. No multimeter needed to perform this conclusive test.

I think this would perhaps be the best, if not most simple test you can try.

Does the UPS report through software that is is providing 90v, or does it indicate normal 115v battery output?

I believe there to be no problem, other than the way your multimeter was marketed as being true-RMS -- which is very likely is not.