temporary overloading my UPS, can i do it?

lamplight · August 2007

Hi fiolks,

i hope this isnt a silly or unanswerable question. I have a older ups rated for 180w
http://www.apcc.com/resource/include/techspec_index.cfm?base_sku=BP280SX116

i want to use this with my new pellet stove im setting up so that i can switch between my offgrid setup and the grid (as sunshine allows). The pellet stove uses about 400w on startup for a few minutes for the igniter, (around 55-60w on low once running). I wanted to use this ups, and the ups will run it during startup with alarm beep during the over rating. I let it go about 30 seconds before unplugging, i wasnt sure if it was dangerous. is it possible that as long as its not on battery during this startup stage it is simply working like a extension or could something be overloading? can that be determined from the specs? i could get a larger ups i suppose if needed but i wanted to use this smaller one if its safe. any way to tell if this is so? also not sure if the type of ac output of this unit is ok to use on a pellet stove? I had no probs on the other one doing this.

Roderick · August 2007

Re: temporary overloading my UPS, can i do it?

Interesting. Are you using the UPS as your primary storage battery, then? I would think (don't know) that a UPS is designed only to provide power in an infrequent outage, and that it wouldn't last long if called upon to provide power every night.

I suspect there is no one that can certify that you can draw 400W for a few minutes from the UPS if the surge rating isn't already on the spec sheet. But I also think it won't be a fire hazard or anything, just that a fuse or protection circuit will blow, or at worst, the UPS will die.

mike95490 · August 2007

Re: temporary overloading my UPS, can i do it?

The data sheet does not list any sort of "surge" rating, so I suspect you ARE overloading the UPS. While on house power, i suspect it will warn you, but when running off battery, it will shutdown, maybe before the ignite cycle completes. You pays your money, and you take your chances.

lamplight · August 2007

Re: temporary overloading my UPS, can i do it?

thanks guys,

i wrote apc (for specs) and the stove company to ask about running modsine ups's. they said anything other than
http://www.secamerica.com/ss_sentry.html
is not certified and voids warranty. great.... looks to like a ups (but probably sine wave, guessing) and it looks like it goes direct to my battery bank and provives instant switching. ill email them to see the details, i dont see any on their site.

roderick: i have a battery bank witha 600w sine wave inverter that i am plugging the ups into. this battery bank is large enough to run the stove indefinitely provided i have some sunny days. in the winter i will likely have the stove (w/ups) plugged into the electric grid. if my batts get full and the sun is out i walk over to the stove, unplug the ups (keeps stove running) and plugin the ups into my offgrid system. i already so this with a larger ups for my home office, its very cool.

anyhow right now my concern is that they probably dont like modsine wave so i wont be able to do this i dont think unless i get some sine wave output UPS. i will see what this secamerica offers.
thanks!

lamplight · August 2007

Re: temporary overloading my UPS, can i do it?

got a response from APC:
(nothing from the vt co yet).

Matt, APC's Back-UPS line is designed for use with Computer-type loads
only. They are not designed to be used with motor loads such as fish
filters, air conditioning units, space heaters, vacuum cleaners or any
other machinery.

One potential issue is the inrush current draw for a motor. It can
easily overload a Back-Ups UPS model. Secondly, these models of UPSs output
a Stepped-Approximated sine wave when on battery. This waveshape,
while ideal for computer-type equipment, is not particularly compatible
with most motor loads.

The Back-UPS BP280SX116 will support up to 180 watts and on full load
it will provide 7 minutes battery backup. However, the your pallet stove
require the power supply of 400 watts on start up, this load is too
high on this unit so that UPS is going to overload. If this occurs
frequently, it may cause to damage UPS and attached equipment.

To protect this type of equipment, APC recommends first determining the
appropriate size UPS for the motor load in question. Ensure that the
Volt Amp rating of the UPS is sufficient to handle the start-up inrush
current draw of the motor. Secondly, select a UPS which outputs a Pure
Sine Wave when on battery, such as a Smart-UPS (minimum of a SU700),
Matrix-UPS, or Symmetra Power Array. Please view the below product
information link:

http://www.apc.com/products/

I am glad I asked this question, looks like i better get a sine wave ups if i want to do this. i learned as much here but this is good clarification. i was unclear as the stove appeared to run fine. perhaps its an issue where the internal components are DC (like a pc) and its internally converting ac to dc (with DC motors) so the stepped wave form doesnt matter (?). i dont really know but i definitely want to play it safe. the smallest unit that would handle what i need is the Smart UPS SUA750 (about $300) i will think about it as technically i dont really need it but the downside of not having it is if i want to switch from offgrid to grid i have to shutdown the stove (10 minutes) and run the startup (high wattage) procedure again. so, longterm it will save some notable power.. hmm..

for those of you unfamiliar APC has a GREAT trade up program: since the ups's in your office have sealed lead acid batteries its VERY important to recycle them, apc's program which ive used a few times allows you to send in your old unit for proper recycling and a discount on your new unit. unfortunately they dont allow you to make a LARGE jump in models so this wont work for me i dont think (email into them).

i also just found out about this company that will offer something for a trade in as well with recycling sent to state authorized locations
http://www.upsforless.com/index.asp?PageAction=Custom&ID=3
might try them if apc says no.

niel · August 2007

Re: temporary overloading my UPS, can i do it?

matt,
most inverters can supply a degree of surge power, but i did not know the design parameters specifically for that apc backups to make a comment on it. the 180w is continuous power within their design for, i believe they said, 6 minutes. what apc is saying to you is that the power surge you are placing upon the inverter is straining the internal parts of the ups beyond what they were designed for even though it seems to work fine. to give you a better grasp of what they were saying, let's use a battery as an example. if you have a 100ah battery and keep drawing 200amps from it, it may seem fine, but how long do you suppose you could keep deep discharging with recharges, even if not exceeding the battery 50% dod, without degrading the battery life? eventually it will give and so may the backups. the battery may take the deep discharge better than many backups with a doubled surge power, but again i didn't design the backups' so i'm guessing.

lamplight · August 2007

Re: temporary overloading my UPS, can i do it?

Just an update: i found out the products from sec america is basically a ups where you can connect and configure your own (user chosen capacity) 12v deep cycle battery, so its also a little charge controller apparently.

heres the kicker: its not even a sine wave output!?! and its the only product you can technically use with a quadra fire pellet or gas stove (what i just bought). i wrote the company after finding this out asking them to evaluate that choice a little more as a sine wave capable ups offers only advantages with no possibility of damage as in many cases the output power is regulated, cleaned and kept constant. it doesnt make sense. i hope the reconsider their stance on that.

i know some of you have talked about measuring the quality of the sine wave from various devices. is this something a hoibbyist like myself can do with a standard DMM? or do you need special equipment? i would like to know for myself and also since i am considering a opti-ups PS800b for sine wave output i am curious about validating how it compares to the household power. this might be beyond me as i have limited electrical understanding, but i have to ask

niel · August 2007

Re: temporary overloading my UPS, can i do it?

you probably lack the equipement to make evaluations yourself so you may need to hear from others that have done this with the oscilloscopes and such that are needed.

lamplight · August 2007

Re: temporary overloading my UPS, can i do it?

ok if something like that is needed i guess that isnt gonna happen as i will probably use it once (if i knew how even). i guess there must be simpler ways then but might provide some good idea: like dont they say things about running an am radio is lousy on modsine, so i could compare that as one simple thing right? irealize this may not be the detail of an oscilliscope but do see see what im getting at, would that be a "pretty good" test of the quality of the waveform (if thats how youd say it)?

temporary overloading my UPS, can i do it?

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