Uninteruptable Power Supply Question

[Czech]

OK all you sparkies out there, quick question. Work has a no longer used Powervar ABCE1440 UPS that I can have for real cheap, I was thinking of using this for backup for my pellet stove. First off, can it be used for this? If so, how long will it run say 200-300W worth of fans and such? I can twist pipe and butcher wood, electric and I do not get along. Some more specs: IN 120VAC 12.0 AMP MAX at 60Hz OUT 120VAC 10.6 AMP at 60Hz Power Rating 1440VA/936W. It could use some batts and before I invest in those I thought I'd check here first. Thanks!

 

[jharkin]

In general Ive read that computer UPSs are not well suited to driving AC motor loads. But to give you a more detailed answer, there is two parts to this ...

First - will your pellet stove run off the UPS at all?

- Does this UPS have a quality true sine wave inverter or a cheap (step function) inverter. If its a cheap inverter it might matter if any of the components of the pellet stove are picky about power quality

- The 300W fan load is well within the UPS load rating, however do you know if there is any start up load that might exceed the rating (I doubt it but worth checking)


Second, If it will run how long will it run. To answer this you need to know the capacity of the batteries and the efficiency of the inverter.

For example, my computer is hooked up to an APC Smart-UPS 1000. This is a 1000VA / 750w unit with a true sine wave inverter. The battery pack is a pair of 12v/12Ah batteries wired in series. 12Ah x 24v = 288 Wh. So if it were perfectly 100% efficient it could run your 300w load for just under 1 hour. However no inverter is perfectly efficient, and its not possible to discharge the batteries all the way down to zero, so in reality I'd guess it could run that 300w load for 30-40 minutes


So my guess is that even if your stove will run on the UPS, you are looking at a run time of under an hour if it has typical UPS size batteries.

~Jeremy

 

[mayhem]

I agree on the runtime...thats a small file server class UPS. Its intended to keep a couple servers running for between 5-10 minutes with a full load draw of around 1000w. You're probably going to get around a half hour at best with your pellet stove running a 300w draw.

One thing though. IT departments rarely part with useful equipment like an operational UPS. If this thing needs batteries, don't pay a penny for it.

 

[Jags]

Rated for 936 W max and stated to run ~20 min at half load (468 w) - at a 300W load your looking at half an hour run time.

I agree - if you need to purchase batteries - it isn't worth a dime. That is a fairly small ups and can be purchased new for 20% more than what the battery replacement is gonna cost you.

Edit: one option is - you can increase your run time by battery sizing. But if you and zoomies don't get along, I would probably not go that route.

 

[Czech]

Thanks guys, this is what I was thinking. I'll take the batts home and load test them and see. In my weird way of thinking, I relate an objects weight with value and therefore was thinking I was rich! I've heard that it is good to have clean true sine wave for the electronics and thought this may provide that. Maybe there's some utility of using the guts for the clean part and bigger batts for the time part? Or should I just ebay it? Thanks again.

 

[Jags]

I've heard that it is good to have clean true sine wave for the electronics and thought this may provide that. Maybe there's some utility of using the guts for the clean part and bigger batts for the time part? Or should I just ebay it? Thanks again.

Your thinking straight. These things are designed to run sensitive equipment (electronics). They will have a pretty clean sine. The reality is that you could simply use larger batteries than the original to improve run time. You will need to know the input dc voltage (12-24-36-48v) and then go from there. If this thing is using one small battery (12V) - you could get 2 bigger ones in parallel and get alot more run time (just as an example).

I run a pretty good sized UPS (3500w) that uses 4 72AH batteries, and will get about 25 min. out if it will all the puter stuff it runs. Its about the size of a dorm fridge and weight 10 times as much.