Use Your Vehicle as a Generator

Leisure-Lee Feb 2021

Ford recently announced they are adding the Pro Power Package to most of the F150 line of trucks. This package allows the truck to power either 2000W, 2400W or 7200W (good heavens, that is a LOT of power) 120VAC appliances and tools. In essence, the truck takes the place of a good, old fashioned gas generator.

Figure 1: 1200W inverter mounted under hood

Those of us involved in the RV and off-grid power business have done this for years. It is nice that Ford has decided to FINALLY add this great feature to its trucks. You can bet that Ram and Chevy will do the same very soon. This is great for emergency back up power. I’m surprised that everyone on the Gulf Coast doesn’t do this, hurricane outages and all. We have figured out the best way to do this to your existing truck/vehicle, both by dedicated engineering and a lot of trial and error.

**Disclaimer: many economy vehicles are not designed to run at idle for extended periods of time. Check with your manual or dealer to get the scoop on your vehicle. Remember, high idle (1200-1500RPM) is good and makes a huge increase in idle time.**

We often do this for contractors trucks, or to enable people to use their vehicle as a home backup generator system. We also do this for RVs, which allows the owner to use the tow vehicle as a generator, eliminating the need for an external generator. If you want to DIY this, here are some tips for you:

1) Most vehicle alternators are only rated to run half load continuously. So if you have a 180A alternator, just expect to get only 90A for an extended period of time. If you really want to know what the vehicle manufacturer recommends, look at their “upfitter” guidelines. For example, Mercedes Sprinter vans have a $1500 alternator that is rated 150A. But if you pull more than 40A continuously, they will void the warranty.

2) Most vehicle alternators output rated current at 1500RPM, and only cool properly at 1200-1500RPM. So plan on finding a way to get your idle up. Many trucks have a high idle function, and some after market “tuners” allow you to set idle. Of course, a properly sized stick on the gas pedal has been used since the stone ages (err, since the Model T ages). 1500RPM is good, 3000RPM is bad!

3) We almost always add a second (or third) deep cycle battery. Regular car batteries don’t like to be loaded as hard as an inverter generator requires. Secondary batteries need to be properly isolated from the main engine (chassis) battery. Having a backup battery bank in your home also makes this a smart solution.

4) Modern engine alternators are “smart” alternators. They often require a “smart” isolator like the Victron DC-DC chargers to properly charge a secondary battery.

5) Last, but not least, mount the inverter in your vehicle, and run a long extension cord into the house. You don’t want a smelly vehicle running right next to your kitchen.

How much power can your vehicle produce? Let’s use a 180A alternator for this example, which can reasonably produce 100A continuously. (Many small vehicles and SUVs only have a 120A alternator, so you only get 60A continuously, ask your dealer what your car can do). At 100A, with a 14V alternator, you can get about 1400W continuously. Compare that to your standard household wall outlet, which is rated for 1850W continuously. So your tow vehicle is a bit less power than a standard wall outlet.

Why use your vehicle as a generator instead of a regular gas generator?

1) You perform regular maintenance on your vehicle, and keep fresh gas in it. Those are the biggest killers of a portable gas generator, so you get all the advantages with no extra work.

2) You don’t have to haul a heavy gas generator around, and the gas cans to supply it.

3) Your vehicle is WAY better engineered than any gas generator. It will stand the stress for years, no problems.

4) Most people only use their gas generator once or twice a year. That is a big waste of money, when your vehicle might be a better solution.

One final note: to connect your vehicle with an inverter into your house is not simple, unless you are an electrician. Give us a call, we can give you some ideas how to do this.

At Leisure Solar, we are electrical experts in all things off-grid, and portable and back up power. We have a lot of other details about using your vehicle as a generator. Call or email, we love to chat about this stuff.