Inverter to Run Pellet Stove

[Qweaver]

I'm going to rig up an inverter to run my pellet stove during power outages.  The label on my stove says the stove is rated at 3 amps.  I'm a little surprised that the pull is that low.  With two fans and an auger motor,  I'd have guessed more.  With a 400w inverter and two deep cycle batteries available I'd have many hours of run time.  I have an 11000 w generator/welder, but it is often down in my shop acting like a welder and I'd like to have a backup on my heater while I go turn the welder into a generator.  Anyone have any experience with battery back-up of a pellet stove?

[Radar67]

I don't have experience with the battery back up you desire, but I have used a few 400 watt inverters. I mainly used them for powering tools out on my property when it didn't warrant dragging the geny out. Things to consider, if the inverter is constantly connected, it is using power from the battery. When your fans and auger kick on, they use 2 to 3 times more amperage than rated.

I used a 400 watt inverter to power a desk top computer with flat panel monitor on one vacation and found the inverter had to be connected directly to the battery. As soon as I typed the BIOS password in and hit enter, I had to turn the monitor off until the machine completed booting up, then I could turn the monitor back on and download my pictures from my camera. If I didn't follow the steps, the fuse would blow.

[John Mc]

Sounds like a small-scale PV-solar set-up, minus the solar cells. One thing to check is whether the 3 amps is continuous or a max surge rating. The motors you have may be small enough that there is not a huge surge, but it's worth looking in to and verifying that your inverter can handle it.

If you have extended outages, you might want to look at a small scale solar set-up... it could extend the life of your batteries.

There is a magazine called "Home Power" that has lots of good articles and information on small scale solar power (and micro-hydro, and wind, etc.). Even if you aren't going with some sort of solar system for charging, you might pick up other useful info. You might want to check them out for tips: www.homepower.com They used to have regular features on very small scale systems, as well as the stuff for people who were living off-grid with large, complex systems.

[Magicman]

I have no experience with your particular setup, but the idea is sound.  Go for it.  Your label says 3 amps which is 360 watts.  Of course, you will be pulling more amps from your battery because of the inefficiency (loss) in the inverter.

You indicated that you already had the 400 watt inverter available.  Try it and see.  The worst thing that can happen is that it will blow a fuse.

Inverters are relatively inexpensive and a 800 or 1200 watt unit would cost  very little more than a 400 watt.  Then you would eliminate "surge" startup worries. 

A battery maintainer would keep your batteries topped off.   

[Qweaver]

Well, I have 150, 300 and 400 w inverters.  The 400w has quit working,(the one I need of course) I tried the 300w and it tripped the breaker when the auger came on.  I gues I'll have to order a 600 w to be sure it will work.    By the time I have opened the main breaker, started the gen and closed the breakers to the house from the gen, my pellet stove has gone into shutdown mode and it takes a restart to get going again.  We knew that the power was going to be shut off for six hours and had everything setup to make the  switch so we were only dead for a few minutes.  If the welder is not on site or down at the shed this could take a half hour or even a few hours.  An hour without heat will not cause a problem but it would be nice to have a way to switch quickly between line power and backup on the pellet stove to avoid the restart.

[John Mc]

The size you'd need for a significant amount of run time might cost more than it's worth, but have you considered a UPS (Uninteruptible Power Supply). They sell these for computers and other sensitive/crucial equipment where a power interruption could cause serious problems. Basically, this is a box that plugs in to the wall, and your pellet stove would plug in to that. The box constantly charges an internal battery, and switched to that battery to run its internal inverter automatically when the power goes out. It may be too expensive to get one that will run your stove for hours, but one to run it while you make other arrangements might be reasonable.

My brother-in-law found on of these that had been thrown out when the internal battery died, and just hooked it up to another, larger battery (might have been an old Marine or RV deep cycle battery?)

John Mc

[red oaks lumber]

don't mess around to much, the control panel on those stoves don't like any power surge or spikes. not to mention they cost north of $150 to replace

[DonT]

During our ice storm of 1998 our power was out for twenty one days.My brother in law had a pellet stove and an inverter.The inverter blew the circuit board in the stove.Luckily the dealer was down the road and had a board for him.he ended up running his off a small yamaha generator.Many here have there houses wired for generators,as well some have there generators set up so they come on automatically and there power is only interupted for seconds.i was driving an engine for the fire dept at the time so I got to see a lot of differant set ups and the pellet stove inverter was one that caused a lot of problems.Now that was 13yrs ago and i am sure things have changed alot.

[TimRB]

Remember, the current draw from your battery will be much more than the 3A shown on the stove label (presuming they mean 3A at 120VAC).  As Magicman has pointed out, 3A at 120V is 360W.  Divide 360W by 12.5V(or whatever your battery voltage is) to get the current from your battery.  In this case, 360W/12.5V = 28.8A.  Call it 30A+ to account for some inefficency in your inverter.

A 200A.Hr battery operating at peak performance (right) will give 200A.Hr/30A = 6.7Hrs operating time.  But batteries are specified at a reasonably small current, usually about 0.1 times their amp hour rating.  20A, in the case of a 200A.Hr battery.  If you pull more current than that, the capacity of the battery is reduced.  This info is usually in the battery manufacturer's data sheet.

Tim

[John Mc]

... My brother in law had a pellet stove and an inverter.The inverter blew the circuit board in the stove.

There are several kinds of inverters. For running sensitive electronics, you want a (more expensive) true sine wave inverter. You do not want a "Modified sine wave" or a "Square wave" inverter -- the dirty power provided by these will wreak havoc on electronics (and no, running the output of one of those through one of those surge suppressors/RFI filter power strips will not solve this problem). Some electric motors also have problems with modified sine or square wave power.

Luckily the dealer was down the road and had a board for him.he ended up running his off a small yamaha generator.

Some less expensive generators also have rather dirty power as well. We ruined a VCR a few years ago. I can't prove it, but I believe it was from running it off our generator on several occasions. Yamaha generators have a very good reputation, however. The higher end inverter-based generators (Honda makes some very good ones) have very clean power - better than what you are getting from the grid, in many instances. Some of the knock-off manufacturers are trying to capitalize on this good reputations by putting a lower end Honda or Yamaha engine on a crappy generator head, then prominently advertising it as a "Honda powered" generator.

[StorminN]

What John Mc said about finding a UPS to fit the bill is right on. They switch the load over automatically (very handy) and most good UPS's are sine wave output – and they get thrown out or sent to the electronic recycler when the battery goes bad. Find one of these that will power your load, and wire it with whatever deep cycle batteries you can get your hands on... done deal.

-N.