UPS output voltage

It should be the same. A cheap UPS with a "modified sinewave" output (AoE pg 673, four phases of 0,165,0,-165V) have an RMS measurement of 115 - 120V, and have a peak (bulk-capacitor-charging) voltage of 165V, the same as a real sinewave. It's possible your computer power supply will work (barely) with the lower voltage. :-)

Brand is APC.

Andy

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You need a way of measuring the peak value of the output voltage - cos that is what the SMPS relies on. A reading of about 150V peak would be OK.

Incandescent lamps and small motors need the full RMS value to operate properly.

.... Phil

How old is(are) the batteries? A model number would narrow down the field a bit.

I don't know what to say about APC. The units look nice, but the scope waveforms I've made weren't what I expected to see. Furthermore, my upper-level model at home failed twice, the second time shortly after replacing the first. So I've been unprotected for a few years.

But the exact same model has worked flawlessly on my identical office computer for 7 years. Somehow my home units damaged its battery and a replacement battery didn't help.

Use a peak reading volt meter. Your USP likely outputs a square wave.

What is "it"?

The output voltage as opposed to the voltage when UPS has been unplugged.

Andy

BackUPS 650

It's about a yr old.

Andy

See if it will power a few 100 watt incandescent light bulbs to full brightness on and off line. If it gets real dim when on battery, most likely the battery is near end of life.

A PC power supply (the intended load) is not a resistive load, like the light bulb.

I did the test with a 60 watt incandescent. The bulb dimmed about 20%.

Replacement batteries are around $30.

Since the current one only lasted about 1.5 yrs, not sure if I want to go that route.

Would it hurt if I continued using it even when battery goes completely dead?

Andy

I decided to get a replacement battery.

I get frequent power outages and brownouts.

Model BE650G1

Since you know far more than I, I would appreciate guidance on what to get.

APC sells batteries as well as other retailers. They want $50.

They probably is a cheaper alternative the same Ah capacity.

Thanks guys.

Andy

My battery does not list capacity. I have seen some that claim 9 Ah.

Andy

My UPS uses an external battery. It's not of a make that anyone here would recognize. It's very basic, rather poor in external finish and internal construction but it does the job and has been doing it for some 13 years.

I use a small car battery of 35Ah capacity which gives me a good backup time. I've never tested the backup time to its limit but it's more than 1 hour when the battery's new. I used the first battery for about 10 years by which time the backup time had dropped to about a minute. The replacement cost around $50 and is still going strong after 3 years.

Good idea.

Can the APC charge it?

I think the factory battery is 9 Ah.

Andy

Super Start Lawn & Garden Battery

$29.99 Each Plus Core: $10.00

Group Size (BCI): U1 Cold Cranking Amps (CCA): 150 CCA Cranking Amps (CA): 185 CA

You really don't know how old the battery was when you bought the UPS unless you can decipher the date code on the battery. Having a lead acid battery sitting on the shelf for a long time degrades it greatly.

If you continue using it, you run the risk of having it not work when you need it. Otherwise, it will still give some surge protection.

Get a new fresh battery from one of the wholesale battery suppliers and you will have an almost new UPS for about half the cost of a new unit. Take the old battery with you and they can recycle it for you.

That's one option.

I like the small car battery option if it would be safe.

Far more capacity at lower cost.

Need more feedback to make the best decision.

Andy

My APS version (not that big) had a molded battery, 24V - it was actually two 12V batteries in series. You'd need two car batts. I'll bet the battery was originally fine, but the electronics screwed it up.