What size power inverter can my truck run?

I bought a 2000 watt (4000 watt peak) inverter. I want to install it into my truck with a 4.3 vortec. Does any one know if my alternator and battery could handle it if I use it while running the truck at idle? Could it potentially damage my alternator/battery if installed correctly? Thanks

From what I can find your alternator might put out around 100 amps (not at idle), which is about 1200 watts, so yes, you might damage something or blow fuses if you hooked up a 2000 watt load to your inverter.


I don’t see why not. It’s been done lots of times. Some install a second battery, separated from the main battery by an isolator, and run the inverter from it. This way you don’t have to constantly idle and potentially run down the main battery.


2,000 watts at 12 volts requires 160 amps which is well beyond the capacity of your alternator even with the engine running at 4,000 rpm. There is no “correct” method to install an inverter that large. You need a 5+ horsepower auxiliary generator capable of 2,000/4000 peak watts.

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What are you going to power with this inverter ?

You will need a direct connection to the battery, power point will do maybe 350 watt, maybe 700 if you want to push it.

Well I was hoping to run tools off it. I’d mostly be using it for camping.

Sorry what do you mean by power point?

It turns out there is a safety feature which warns you when your battery drops to 10.5 volts.

A small gas generator will be much more efficient and you won’t burn up your alternator or rundown the battery . Tools ? Think cordless .


Power point would be similar to the old cigarette lighter plug in.

A 120 amp alternator will put out 90 to 100 amps at idle, about half of what you need to supply 2000 watts. Operating the alternator at capacity will cause the alternator to overheat and fail after a period of time, could be 15 minutes, could be an hour.

If you are operating a saw or a drill for 10 seconds at a time this probably will do no harm to the vehicle.

Good grief, why not just buy a generator, since that is what you really need? Even the higher-capacity alternator which is offered for fleet and law enforcement vehicles is unlikely to provide the power output which you seek. A 120-watt stock alternator certainly isn’t going to cut it.

I was just asking a question

No need to be a jerk

I have a feeling many here assume that you will draw all 2000 watts all at once for prolonged periods. That’s like running 20 100W light bulbs That is a silly assumption.

  • 2 burner electric camping stove 50amps
  • electric chain saw 12-15 amps
  • battery charger 20-50 amps
  • cordless drill battery charger 14 amps
  • Camping fridge ~50 amps (when cooling)

As said previously, if you use a second battery, isolated from the first one, you will not have to worry about damaging or running down your main battery. My son-in-law had an inverter in his camping truck for many years without any problems. Enjoy



I’d be worried about blowing your alternator. Alternator failure rates rise when they’re delivering full output for extended periods of time. When your inverter is drawing 1200 watts, your alternator will be delivering full output.

If you draw more than 1200 watts (or whatever your alternator can produce) for an extended period of time, you also run the risk of ending up with a dead battery, even though your truck was idling.

Kurtwm1 noted an approach to reduce risk. Along that thinking, if it were me and I had a 2nd isolated battery, and the inverter had a display on it where I could make sure I wasn’t drawing more than 50% of max alternator output, then I would use that option.

But rather than the above, I would much prefer getting an Inverter generator. There are lots of quiet ones available for camping.


I think the poster is just asking, as he said.

Your 50 amp stove = 6000 watts
Your 15 amp drill = 1800 watts

Pretty sure he’s talking about 12V, not 120V, so cut those watts by a factor of ten.