UPS idle power

My experience is that you'll be looking at circa 20-30 VA idle load battery drain equivalent. i.e. don't expect more than a couple hours of hang time.

The AC out waveforms with very little load, may look quite bizarre. Those low-end UPS inverters are designed to run at a quarter to three quarters loaded capacity and only for brief periods.

It's just the power to drive the logic and the magging current of the inverter transformer. I would think a few watts. It would be trivial to break the battery line and measure the current. Most of the smaller ups's of that sort that i've seen used tagged lead acid batteries, so it's easy to get to the terminals.

Measurement always better than guesswork :-)...

Regards,

Chris

Certainly. It's also true that it's trivial to measure the idle current except that, as I said, I don't have immediate access to an internal battery type at the moment.

I tested my Minuteman Office Plus 1000 unplugged and no load. It measured .265 amps from the 12V battery.

Helps?

Cheers, John

Thanks. Last year, I used a UPS in similar circumstances, but with an external battery and roughly 10 times the load. The battery was a 70 Ah type but was ~6 years old and probably had a much reduced capacity. It lasted for two days at about 5 hrs of usage per day, with occasional switch-off periods during those 5 hours.

Yep. Thanks.

Oops! Office Plus 500.

'scuse me.

John

Conext 900 AVR with 12 AH battery - .721 Amps.

Do confirm you can start the UPS without having A/C power initially. I have seen UPS units that won't start up unless the actually detect a power failure.

If you're interested in max run time at low load, why use a 600VA ups. I've found that standby currents vary widely. I have a 20 year old "Focus" brand Chinese 140W/200W surge 12VDC/120VAC inverter that idles at 40mA at 13VDC. That's the best I've found. Typically, these are 4-6x that.

I agree completely with the logic of using an inverter of lower power, and therefore of lower standby current drain. The problem is that I live in a place where I have few choices. I've even considered rolling my own, but it's unlikely that I'll be able to fit it into the time frame I'm working under.

Interesting. If I had few choices, asking general questions wouldn't be helpful. If it's all you got, it don't matter what the current drain is. If you've got it, you can measure it.

You have to know exactly what you're plugging in, but losta stuff will run off DC. Generating 160VDC is simpler than generating psudo AC.