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UPS idle power

Can anyone give some ball park figure for the idle (unloaded) current consumption of a low-power (~600VA) UPS using an internal

12V battery? The ones I've seen use 4 to 7 Ah batteries.

I can't measure it because I have only external battery types with me. These may or may not be different from internal types in their idle consumption. I expect that the idle power will vary from brand to brand and model to model. But I need to have at least a rough idea, based on manufacturers' specs or someone's experience, not a wild guess.

Reason for asking: I need to do some field work with equipment that need AC power, but a public supply won't be available. The UPS will be idling at ~5VA load most of the time, with a peak of ~15VA for about 5 seconds at intervals of 1-3 minutes. So most of the load on the battery is likely to be the idle consumption of the UPS. I'd like to be able to estimate how long the battery will last under those conditions.

Reply to
Pimpom
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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.

Reply to
Tim Shoppa

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

Reply to
ChrisQ

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.

Reply to
Pimpom

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

Helps?

Cheers, John

Reply to
John - KD5YI

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.

Reply to
Pimpom

Yep. Thanks.

Reply to
Pimpom

Oops! Office Plus 500.

'scuse me.

John

Reply to
John - KD5YI

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

Reply to
John - KD5YI

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.

--
I'm never going to grow up.
Reply to
PeterD

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.

Reply to
mike

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.

Reply to
Pimpom

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.

Reply to
mike

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