Power Inverter use

I live in Louisiana, also known as Hurricane Alley. Due to hurricane Gustav we just got our power back after being without it for five days. I do not own a generator because of the space they take up and the need to have gasoline for them. My wife has a Mercedes E320 diesel engine car. I am thinking of purchasing and using a 3000 watt power inverter which I will connect to her car via the battery posts. Will it cause any damage to the engine or the cars electrical system to let it idle continuously for days at a time to run the inverter? A full tank of diesel would probably run for a week at idle without a need to refill it.

First, if you are going to install a 3,000 watt inverter, have it done professionally so it doesn’t catch fire like they are prone to do in commercial trucks. I am not sure you can even install an inverter that large in a vehicle with only a single battery. I recommend a smaller inverter that plugs into the cigarette lighter/power outlet. They are less likely to ignite but they can only power small appliances. They also have built in fuses in addition to the power outlet’s fuse.

Any time you connect an inverter this large directly to a single battery, you create the potential for a fire. This is especially true of an inverter as large as 3,000 watts. Hire someone to do it so that the inverter is properly cooled and the connections have proper fuses in the proper places. Converting DC to AC is very inefficient. Using it to generate 3,000 watts of AC will really challenge the car’s ability to produce DC.

If you were planning to power your refrigerator with this inverter, get a large electric cooler that plugs into the car without an inverter. You can find them at truck stops.

Lastly, a commercial diesel truck uses about a gallon of diesel fuel per hour to idle. Although your car will use less, it doesn’t have a special idle setting like a commercial truck. So you probably will need more fuel than you think.

3000 watts? I think that would be way too much for a regular car system to handle…waaaaay too much.

I am not sure if you have a propane tank at your location or natural gas already. I would suggest a portable or fixed unit fired by one of these fuels. A 3000 watt unit is not particularly big. Gasoline and diesel generators are a pain in the fact of the fuel storage and need to turn over the fuel since it ages.

The major issue with an inverter is that you will destroy the alternator (likely $1000+ item on MB) in short order running it for a week with a single car battery.

3000 watts would require 250 amps W=IE;I=W/E i.e. 3000/12=250. You can’t possibly pull 250 amps from the car alternator. The alternator is probably 100 amps or so and that’s at full rating before losses and the battery would just be a big resistor. Buy a Cummins Onan Quiet Diesel generator like those used in an RV. They are relatively small and run quietly i.e meet US Forrest service limits for noise and have flame suppression exhausts.They will power your major appliances.

Before you try this, talk to a Mercedes mechanic about the output from the alternator. Watts = Volts x Amps. Your car’s electrical system is 12 volt. To get 3,000 watts, you need at least 250 amps. This is far more than most alternators can produce. For that much power, I don’t see any alternative to a portable generator.

Can you get by with canned food, a gas camping stove, bottled water and LED flashlights? The car should be able to run a 12 volt TV or radio or an inverter big enough to handle a small, 120 volt TV or radio. If you absolutely need a refrigerator, consider a 12 volt model.

I think that the average alternator is 1500 watts or less. If your inverter puts out 3000 watts, it probably needs 4500 watts input. Also, don’t expect such an inverter to handle loads like a fridge’s compressor very well. You’d be much better off to get a real generator. They have small diesel ones. A natural gas one would be better though.

No color television will run on an inverter plugged into a car’s cigarette lighter/power outlet. The inverter would have to be directly wired to the battery. Instead, I recommend a television that has a 12 volt plug of its own. You can find them at truck stops.

Not true, some Flat-screens are less then 300 watts, and would work.

I stand corrected! I was thinking about CRT televisions.

Of course, a battery powered 6" B/W TV goes for about $15 now. However, it won’t work after the coming DTV switch.

I agree with the others who warn you that 3000 watts is too much for an automotive system.

I suspect 1000 watts may be your limit. With this amount you could run a few lamps, the radio, an alarm clock, your battery chargers, and a few other odds and ends. Nothing larger. It’s not ideal but it would help you through the crisis.

Gasoline and diesel generators are a pain in the fact of the fuel storage and need to turn over the fuel since it ages.

Gasoline deteriorates rapidly (oxidizes into gums and varnishes); even with a stabilizer added it won’t last long. However, I thought diesel was fairly stable… does it have to be turned over in any particular time frame? I know that big stand-by generators are either diesel or LPG.

There is a great deal of wisdom already posted but I will add, that regarding Ohms law, and 3000 watts, even a 100 amp alternator at 12 volts(nom) is 1,200 watts at several thousand RPMs. At idle, the alternator likely produces less than 250 watts.