Extended Power Outage Experience

[wilbilt]

It has been a memorable few days here in NorCal.

We had a storm come through last Friday morning that was a real screamer in terms of wind gusts. The wind took out trees and power lines in a large area. The power at my home went out at 5AM Friday and was not restored until noon today...about 55 hours total. Most of my neighbors are still without power.

My old Trailblazer stove has 12V binding-post terminals on the bottom for backup power connection. Since the LP-fired furnace is useless without AC power for the blower, the pellet stove was the only choice to keep things warm.

I know the preferred battery for backup is a deep-cycle marine or RV battery; I have one of those, but after attempting to charge and use it a few weeks ago, I can see it is beyond it's useful life. I chose to use vehicle starting batteries instead, and rotate them to make sure one of the cars was always operational.

I found some suitable wire (12AWG stranded) and attached some spade terminals to connect it to the stove. At the battery end, I used some terminals with wing nuts on top I had lying around. When I first tested the operation of the stove, it was obvious that the blower speed was quite a bit slower than when running on AC power.

I lit the stove and turned on the blower after the pellets in the burn pot had all ignited. After getting a good flame, I started the auger. When running on "low", the auger operation was intermittent at best. On "high", however, the auger operated normally.

Due to the reduced fan speed, I had to watch the stove pretty carefully because the pot had a tendency to fill up with unburned pellets. Switching the stove to "off" stopped the feed and increased the fan speed, so I did this fairly often to burn up the piling pellets. This old stove has a tendency to overfeed anyway, so I don't really consider this to be an issue (especially considering the alternative...freezing...).

I was worried about draining the battery too much. This proved to be of no concern. The first battery I connected I ran for about 5 hours before switching to the battery from another vehicle. I reinstalled the first battery in the car it had been removed from, and the car started right up. I ran the second battery for about 24 hours before switching it out, and it also started the vehicle without any problem. I was originally thinking a battery might last an hour or two on the stove. I was happily surprised that they lasted much longer.

AC Power was restored to my home at about noon today, and I switched the stove back to outlet power. The increased performance was immediately noticeable. I now know that I can run the stove during extended power issues without difficulty. It does take a little more "babysitting", but this old stove is pretty basic, and requires more of a manual touch anyway.

Just sharing my experience...

 

[sherri]

Sounds like everything came out well then. We have yet to buy battery back up for our pellet stove. January of 2007 we had an ice storm here in Missouri that put the power out for some people for as many as 14 days. Ours was out for about 8. We ran our pellet stove off of a generator and I'm telling you it saved our butts because no one had power or heat or anything. I think all of the babysitting is definately worth not freezing.

 

[begreen]

It's a good idea to have a voltmeter as a permanent part of a battery backup system. That will take the guess work out of when it's time to charge the battery. You don't want to run the battery below 11 volts, perhaps even higher if you are hoping to start the car with it afterward.

Many cars have a towing package option where a heavy duty battery is installed. If there is an option to install a higher capacity battery in your car, this might be a good insurance policy.

 

[wundercat]

An "automatic" battery charger can be connected to your deep-cycle battery and left on.
They're made so that the battery charges up to full, then goes into a very low power "float charge" mode.

This keeps the battery at peak charge without overcharging it.

Just about any department store or automotive store will carry one of these chargers.

 

[pegdot]

Since the auger and the fan were both running slower than normal I take it that they weren't receiving enough amperage. Will running one like that for an extended period of time damage the motors?

 

[Highbeam]

When you send insufficient voltage to a motor, the windings suck more current to try and get to the rated HP. Eventually they try and suck so much current that the motor can burn up. So yes, undervolting a motor is bad.

 

[wilbilt]

When the batteries were first connected, they were definitely up to voltage. It was immediately apparent that the fan was running slower than when on 120VAC power.

I don't know if this stove has 12V components running on a built-in step-down supply or if it has a built-in inverter and 120VAC parts. It sure would be nice to find a manual

I do have a Fluke DMM, and was meaning to keep tabs on the voltage....but I was busy with other tasks.

 

[pegdot]

Thanks, that's what I thought. I have a generator so this is really more to satisfy my curiosity but is it possible to get a batter back up that supplies enough juice to the motors to eliminate the possibility of doing damage to them?

 

[Highbeam]

Well to get proper juice to the stove I would use a good inverter to create 120 AC current from your batteries. The good inverters have nice output, and have low voltage warnings and then shutoff. Yes they will consume some power just going to AC from DC but if you want to use batteries as back up power then you will need to get into inverters. Since the inverter shuts off before sending low voltage to the motors, the risk of damage is low.

Many of the off-grid or solar type guys power their entire homes with a battery bank linked to a nice inverter. I don't believe that the stoves are such sensitive devices that inverter created AC will damage them. We use the UPS to power our computers in the event of a power outage and isn't a UPS nothing more than a battery/inverter combo?

 

[tinkabranc]

We use the UPS to power our computers in the event of a power outage and isn't a UPS nothing more than a battery/inverter combo?

Only problem I am finding with using my UPS I have is that it is great to have for blinks in the
power but it does not hold a charge very long.

I am back on a mission of researching if I should hook up to an inverter instead now.
Going bigger on a UPS is expensive.

I have lost power 3 times in the past two weeks while the stove was still running and the
UPS only lasted about 15 mins max.

I do have a generator for long term outages but it is a monster and hard to move around.

 

[wundercat]

Here's a really simple UPS that you can build for yourself.

Wire two deep-cycle marine batteries in parallel.
Get a 30amp automatic deep-cycle battery charger and connect it
to the battery bank to keep it charged.
Connect a 1500watt inverter to the batteries and plug your stove into that.

Leave the charger plugged in and set to "deep-cycle" mode. Leave the inverter
turned on and just run the stove from that all the time.

If your outside power blacks out, the stove won't even hiccup. The charger
will bring the batteries back up when the line-power returns, as well as
providing all the overall power for keeping the inverter running.

You can add solar panels or wind power to keep those batteries topped off and
assist in powering the inverter. You can also run the charger from a generator
until the battery voltage levels off at full. Then you can shut off the generator
and save gas for a while.

A typical 1500watt inverter won't even get warm with a load of less than 750 watts.

 

[Highbeam]

Might want to increase the size of the converter (charger) from 30 amps to 60 or so. The charger makes 12 volts and at 30 amps is 360 watts only which means that your pellet stove will be sucking more out of the batteries than the charger can produce. The RV guys have some very large converters that put 60 and more amps of DC into the batteries. Also, as you charge these batteries they boil and realease gas into the air so it would be a good idea to locate the battery bank somewhere safe.