Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Power House With Inverter?

During the ice storm we had in Massachusetts, a friend told me he powered his oil burner and circulator pumps with an AC inverter connected to his truck’s 12V convenience outlet. He ran his truck on and off for two days as a poor-mans generator. Seems like this could damage a vehicles electrical wiring with too much current draw. But it worked. What are the risks?

NOT!! Your “friend” is BSing you…The oil burner will draw more watts than ANY “12 volt convenience outlet” will supply…Most heating systems will draw at least 1200 watts, which means 100 amps at 12 volts. Your friends truck and it’s 70 amp/hour battery could power his furnace for maybe 5 minutes at most…The inverters that have lighter plugs on their cords have a maximum rating of 200 watts. Not enough to power ANY furnace motor…

There’s nothing at risk, as long as you size the inverter to handle the power you wish to consume. And the more power you wish to convert, the more expensive the inverter is.


Notice that the original post said that he powered the oil burner motor and the circulation pump. The oil burner motor is a fractional horsepower motor that shoots a vaporized spray at the electrodes where the oil mist is ignited. When the OP said circulation pumps, I assume that this is refering to a hot water system with an oil fired boiler as opposed to a forced air furnace. The air handler motor on a forced air furnace would draw more power, but even a 1/2 horsepower blower motor would draw in the neighborhood of 7 amperes. The circulation pumps may also have small fractional horsepower motors. The current draw at 120 volts may be way less than 10 amperes.` I think that it is possible to run a boiler system with power supplied through an inverter connected to the truck’s electrical system.

Our house was without power for four days with recent the Massachusetts ice storm, and I ran the heater with a 400 watt power inverter from my car.

I have a forced hot water gas heating system with three zones. Each zone circulator pump draws about 110 watts. The electronics to “turn on” the furnace draws less than 5 watts.

I ran all three heating zones for about 7 hours/day. I did keep the car idling in order to keep the battery charged. I figured my 12 volt car alternator was having to deliver 30 amps tops to power the heater.

Unless you pay a lot for your power inverter to get the models that produce a true sine wave, you’ll likely get one that produces a “modified” sine wave. The modified sine wave did cause the zone circulators to “humm or buzz” slightly, but they still ran fine.

I would not want to run a more powerful inverter for extended periods. You run the risk of having your alternator produce its rated maximum and still drain your battery dead.


You can actually buy generator kits from some trucks that actually consists of basically a big generator that bolts onto the engine. I think they cost more than an actual generator, though.

My father in law has a 3500 Watt inverter. My father in law hooked his runninh F150 to a older truck battery and then had the inverter on that(it use very heavy cords-look like jumper). His normal use is to run a power or tile saw off his work van instead of fishing around for power.

He was able to power the oil boiler with two zones and small circulatar pumps. With that during our recent ice storm his home was in full business with hot water and heat. He was thankful for a propane powered stove.

I would not directly connect the inverter to the truck’s battery but use a battery hooked in intermediary to temper the load.

The circuit on a oil boiler is usually only 15amp.

I guess it depends on what you have to power. I lost power for 5 days. Can live without heat…but NOT without water (well). I have a generator that powers the heat system…water…refrigerator, some lights and the stove/oven. If I eliminated the frig and stove from the equation I MIGHT have been able to run on a generator.

If the inverter is plugged into an accessory plug (or cigarette lighter), you will blow a fuse before you do any real damage. If you don’t blow the car’s fuse, you will probably blow the interter’s fuse.

If the inverter is one of the larger ones and is hooked directly to the battery (or a series of batteries), there is a real chance of starting a fire, especially if you use substandard wiring for the connection, but at least in this configuration it would be possible to power that kind of equipment.

In one way or another, your friend is probably pulling your leg. Perhaps he ran an inverter off a series of batteries and used the truck to recharge those batteries?

“a friend told me he powered his oil burner and circulator pumps with an AC inverter connected to his truck’s 12V convenience outlet.”

These 12 volt lighter plugs are invariably fused at 20 amps. Volts X Amps = Watts. 20 X 12 = 240 watts. 240 watts is all you can pull from a cigarette lighter plug type inverter…If you can power your homes heating system off that, more power to you! A FAR better solution for power outages is a 1500 watt gas powered generator which will carry your lights and refrigerator too and not require running a vehicle at fast idle and hoping the alternator does not burn up doing something it was not designed to do…In E-bays search window, enter “1500 watt generator”. You might be surprised at what is available…

Mike . . . did you hook a generator to your well pump? I was thinking of just that problem when my Brother-in-law called during the power outage from Berwick, Maine, last week. How would one power a direct-wired well pump with a small generator? Rocketman

Yes, your friend probably did. The key here is that he must have had a hot water circulating system, not a forced air system. The circulating pump on my system was 1/25 hp, rated at about 3/4 amp max, or 80 watts for 110 volts. Thats about 7 amps at 12 volts. The power to run the oil burner can’t have been much, so the overall load was pretty low.

I had a separate panel wired up that is connected to the pump, frig, stoven/oven, furnace (pumps, fans) and a few choice lights and outlets. There’s a access plug outside. I pulled generator from shed…started it up…plugged it into the outlet.

BTW…My generator is now in South Berwick ME at a friends…He STILL doesn’t have power.