We Charged a Ford Mustang Mach-E With an F-150

We’ve powered many things with the optional 7.2-kilowatt Pro Power Onboard generator system of our 2021 Ford F-150 Limited hybrid, even using it for backup power during installations of electric car chargers at a couple of our editors’ homes. So, it was only a matter of time before we attempted to charge an electric vehicle with the truck itself. Is it possible? Yes, but it’s not without limitations, and we’re not saying it makes sense for anything but emergencies.

Related: Game Changer: Using Ford F-150’s Pro Power Onboard for Off-the-Grid Camping

To do this, we needed an EV, and while it’s not necessary to match brands, we happened to borrow a 2021 Ford Mustang Mach-E at the right time and set about our experiment charging a Ford with a Ford.

The math works, sort of. Pro Power Onboard produces 7.2 kW, with a 240-volt outlet rated at 30 amps. If it helps everyone’s understanding of the many numbers to come, power is measured in watts and is a product of the voltage (likened to an electric form of pressure, measured in volts) and the flow of current, measured in amperes (amps for short). The 240 volts multiplied by 30 amps is 7,200 watts. We convert higher numbers like these to kilowatts, which is how we get 7.2 kW.

The Mustang Mach-E has a generous maximum alternating current charging capacity of 10.5 kW, meaning it can draw more power than the F-150 can provide (7.2 kW), so whatever charger we’d use between the truck and the car would have to be rated at 30 amps or lower to avoid tripping the truck’s circuit breaker. (This is a bit difficult for people to grasp because it seems like the opposite — more current at the outlet feeding a device with lower capacity — would pose some kind of risk. But in reality, the device — the charger — serves as a bottleneck that limits the amount of current flowing through it. It’s when the charger and EV are rated higher than the circuit feeding them that the circuit breaker will trip over and over and get you nowhere.)

Ford kindly includes with a Mustang Mach-E purchase a Ford Mobile Charger with interchangeable cords — 120 or 240 volts — but it’s rated at 32 amps when operating at 240 volts (for 7.7 kW), which is too high for Pro Power Onboard’s 30-amp outlet.

The other option for the mobile charger is the 120 volt-cord, but that mode has a lower limit, 12 amps, and in this case, you’re multiplying it times 120. And 1,440 watts isn’t enough to make a dent in the Mustang Mach-E’s state of charge.

Instead, we used Managing Editor Joe Bruzek’s Level 2 charger, the only charger we own that has a plug (as opposed to being hard-wired to one of our homes) and fortunately is also a type capable of throttling its charging level down to accommodate this type of scenario … well, maybe not this scenario with a truck, but one like it where an outlet that’s part of a building doesn’t have enough current to satisfy the EV’s needs.

Like most chargers of its current capacity, Bruzek’s Electrify America HomeStation has a NEMA 14-50 plug (the 50 represents a 50-amp maximum rating). The Pro Power Onboard system’s 240-volt outlet is a twist-lock L14-30 (30 for the 30 amps mentioned above). Simple adapters that allow these two pieces to work together are available for use with generators, but in the interest of flexibility, I instead built my own with mostly on-hand parts and added an inline circuit breaker box for an extra level of protection for both vehicles and the expensive hardware involved.

Unfortunately, the Electrify Home charger’s current options, which you can adjust using the smartphone app, are 40, 32 and 16 amps. What we wanted was 30 amps, but we had to go all the way down to 16, which translates to a theoretical 3.84 kW. That’s not very effective for a car capable of accepting 10.5 kW, but we gave it a try.

The First Attempt

We began with the Mach-E’s state of charge at 55% and a projected range of 131 miles. We started the truck, hooked everything up and began charging. The Pro Power Onboard display on the truck’s big touchscreen showed a 1,800-watt draw on both meters, for 3.6 kW total. (A 240-volt circuit has two separate “hot” conductors, and the F-150 has a readout for each leg.) I also attached a clamp ammeter to my adapter rig, and it read 15.9 or 16.0 amps, as expected.

According to the Mach-E’s instrument panel display, at this rate the battery would be full in … 14 hours.

This wouldn’t do. We decided to go for broke and at least see if the car would charge at 32 amps. We stopped our 16-amp experiment, fired up the app, switched the HomeStation charger to 32 amps and started again.

The Second Attempt

This time, we watched the ammeter and Pro Power display intently. Charging began. First the draw was a mere 1.6 amps. It began to climb gradually, soon shooting past the 15.8 amps from before. At 22.8 amps — and 2,500 watts on both A and B gauges — the truck’s engine started to keep up with the draw. The ammeter passed 30 amps, climbed to 31.8, 31.9 … then 0.

Sure enough, when the current draw hit 32 amps and the in-dash gauges read 3,600 watts, the truck’s circuit breaker tripped. The entire ramp-up and shutdown lasted just 41 seconds.

The Sad, Plodding Reality, Take 2

With no better options available, we restarted the 16-amp charging test to see what we could accomplish. After one hour, the Mach-E had added 4% to its battery’s state of charge and 10 miles to its estimated range. During that hour, the Pro Power Onboard gauges again read a steady 1,800 watts apiece while the truck’s engine idled at a constant 1,000 rpm. Knowing how many miles of range we can add in an hour of charging with a maxed-out home charger (well north of 30 miles), this is pretty lame. But the cause is clear.

Before I delve into how much gas we used and the use case for charging an EV with an F-150 equipped with Pro Power Onboard, I’ll lay out a few ways this could have gone differently:

• If we happened to have a Level 2 charger rated at 30 amps (which do exist), it probably would have almost doubled the miles added in an hour’s time.
• If the Electrify America HomeStation charger didn’t have such a wide chasm between current settings, the Mach-E would have charged faster. Other adjustable chargers we own that come with plugs (but we had hardwired), the ChargePoint Home Flex and Wallbox Pulsar Plus, both have 24-amp settings, which would have helped.
• Ford could have helped a brother out by making the Mach-E itself adjustable for current draw, as some competitors do; Tesla has long done so with 1-amp divisions. With this provision, you could theoretically attach a Level 2 charger rated as high as the maximum 80 amps to Pro Power Onboard and simply use the car’s touchscreen to set its draw to 30 amps. Ford said no such enhancement is planned for the Mach-E but that the F-150 Lightning all-electric pickup will include a 30-amp mobile charger instead of a 32-amp one, so it would work with the Mach-E. (The Lightning’s Pro Power Onboard will be rated higher than the hybrid’s, though, at 9.6 kW, meaning a 32-amp charger would be fine for that application. The mind boggles.)
• Batteries charge slower (and demand less power) as they fill, so ironically, the Mach-E probably would have charged anywhere between 16 and 30 amps if we started with the battery pack fuller than we did.

But ultimately, we can’t see any reason to use Pro Power Onboard to charge anything but a completely dead EV for the following reasons.

EV Charging With Pro Power Onboard: For Emergencies Only

There were no surprises in this test, but perhaps the numbers will convince you that using gasoline to generate electricity to charge an electric car is a terribly inefficient and uneconomical way to go — which is exactly why series hybrids haven’t caught on.

We intentionally filled the F-150’s tank and used the same pump right before and after the test at a station just a few blocks away to minimize fuel usage from driving. When the experiments were done, we topped off with 1.6 gallons at a cost of $6. The charger’s app said it provided 4 kilowatt-hours total to the Mach-E, which seems a little generous, but even so, that works out to $1.50 per kilowatt-hour. The national average runs about 13 to 14 cents per kilowatt-hour for residences, and even DC fast charging at Electrify America was only $0.43 per kilowatt-hour at the time of this test.

But if the EV in question has a dead battery, the proper comparison is to the cost of getting it towed home or to a DC fast-charging station — something I once witnessed personally while Supercharging a Tesla. The driver looked sheepish as his Model S rolled off a flatbed directly into a Supercharger space. Perhaps he misjudged or had borrowed the car and wasn’t aware of the risks.

In this scenario, even 5 miles of range might have been enough to get a stranded Mustang Mach-E to a station or a parking lot rather than a hazardous roadside. From this perspective, $6, even with a markup, seems like a bargain. We wouldn’t be surprised if mobile DC fast charging, a concept we tried out in prototype more than 10 years ago, begins to proliferate along with EV adoption. Yes, it’s faster, but the investment is much greater, and a Ford F-150 with Pro Power Onboard can do the job. If you have the right hardware, or are charging a more cooperative EV, you can do it faster than we did.

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