Wednesday, February 8, 2023


RVelectricity – Just Ask Mike (J.A.M.): More ways to recharge an EV on the road

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) with the subject line – JAM. Today I discuss more ways to recharge an EV on the road.


Dear Readers,

I’m getting a lot of response and opinions about my J.A.M. Session a few weeks ago about recharging an EV on the side of the road with a portable generator or Solar Power Station. So I’m going to cut through all the dross and tell you the basics of how roadside recharging could work. Note that I do all the calculations and field testing myself, so this isn’t some wish-list proposed by some company with a horse in the race. These are calculations and possibly test results from my own FunkWorks Lab.

Alternate fuel Model T cars (we’ve been here before)

The Model T was built and sold in the USA from 1907 to 1928, back when there were few roads and even fewer gas stations. So there were a few multi-fuel kits you could add that would allow you to run it on anything from high-proof ethanol (moonshine) and/or kerosene.

Now, Ford did not officially endorse this multi-fuel concept, but I’m pretty sure there were a bunch of farmers who would try anything. And apparently it worked. I’m pretty sure that this same can-do attitude still exists in America, and I’ve found at least one possible solution for roadside emergency charging of an EV (and probably a few others).

Portable generators won’t work for recharging an EV

As I noted in the previous article, recharging an EV using a Level-1 charger with a portable generator isn’t really practical. Consider that a standard 16-amp Level-1 charger can output only around 1,900 watts of power to the EV. So in each hour of running, it could only add around 5 miles of driving range to a typical EV. That works out to around each mile of added range taking 12 minutes of generator time, which is 1/12 of a mile per minute. Pretty slow…

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Large trailer mounted generators will work, but may be overkill

And yes, I’ve worked out the math of putting a large diesel generator on the back of a flatbed truck or a trailer with a Level-3 charger that could provide around 50kW of power.

So it could recharge an EV at a rate of 3 miles per minute. That’s nearly Level-3 fast charging mode. But it could only charge one vehicle at a time and would require a 3500 series truck to haul it around. Still, it’s a good concept that would work for many locations.

Perhaps swappable batteries in a Level 2+ charger could work

But what if I told you there was a way to split the difference, as it were? There is an EV charging system called the SparkCharge Roadie. It uses swappable battery packs that can charge at a rate of 1 mile per minute, and each battery pack can add around 15 miles of range to a typical EV.

And these battery packs and Level 2+ chargers are small enough that up to 4 of these chargers and maybe 8 battery packs could fit in the back of a pickup truck.

Here are the numbers on paper

Now, what if I told you these Roadie battery packs could be recharged in the back of an F-150 PowerBoost truck with the optional 7.2kW generator. Add in a 60-gallon auxiliary gas tank to the PowerBoost truck. Now you have an emergency response vehicle that could charge up to 4 EVs at a time, adding from 14 to 28 miles of range per EV. It could do this for a few days on the road during a snow emergency without having to refuel.

Of course, this isn’t cheap enough for a consumer, since each single battery pack or charger is around $4,500. Plus, if you want it to self-recharge on the road, you need to put it in a $65,000 truck. But that’s certainly affordable enough to be deployed by the state highway departments along long routes like I-95.

Note that I’ve already tested the on-board 7.2kW charger in a Ford F-150 PowerBoost Hybrid truck, so I’m confident that part of the equation would work.

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Will the cost come down eventually?

I’m sure as battery density increases and prices decrease, this will become a more affordable option for even AAA service stations that need to rescue a stranded EV.

While lithium batteries are the current favorite technology, I’m sure there are even higher-density, lower-cost solutions out there. Just remember how little available power carbon-cell batteries there were just 50 or 60 years ago.

Please let me test this concept…

I’m proposing the idea of testing this concept to both Ford and SparkCharge. If I can get traction (and a budget), I’ll see if it actually works. And no, I don’t think that the Ford Lightning is the right vehicle for this test.

Note that the F-150 PowerBoost is a hybrid gas/electric truck that will power its built-in inverter generator for days on a tank of gas while running at idle or driving down the highway. I personally tested that truck last summer.

In the meantime, I’m studying everything I can about keeping EVs running on the road, because I’m sure that will happen eventually. Just how fast and how soon is the big question. But I can only work on what I have in front of me.

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Send your questions to me at my new RVelectricity forum here.

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.

You don’t want to miss Mike’s webcasts on his YouTube channel.

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Matt Ross
9 months ago

Mike, can I charge an EV from an 8,000 kw diesel generator on a class A motor home?

9 months ago

Similar to to the concept described in Mike’s article above, here is one where the author describes a successful test using a F-150 Powerboost with 7.2 kW Generator connected directly to a Tesla. The claim is that he achieved a full 7.2 kW at 30 Amps of input to the EV.

Using the Tesla battery pack as an example, it currently claims a 82 kWh capacity with 353 miles range and is said to be charged at a rate of 39.7 miles (63.9 km) range per hour (240 V 48 Amps) per this source

With only 30 Amps output from a Ford F150 at 240V x 30 Amp x 1 hour = 7.2kWh of energy pumped into the EV. So 7.2 kWh is ~8% of the 82 kWh battery capacity and 8% of a 353 mile range is about 28ish miles of range in a hour of charging. Not bad, but not great. With Level 2 charging at 240 Volts I don’t think you will get much better.

9 months ago

I’m still hearing no news reports about adding new transmission lines to the electrical supply grid, nor anything about new generating plants. I do hear a lot of grumbling about increasing wind farms and solar panel fields. And we can assume that nuclear is dead, dead, dead. No politician dare touch it; it’s a third rail of political suicide.

Meanwhile, here in WA state, the Governor and Legislature are ramming through new legislation for an outright ban on residential home heating with natural gas and propane in any new construction by 2030. Homes are to become All-Electric with solar and heat pumps. Conversions to follow. Gas cooking stoves and gas water heaters may be banned, also.

Call me Luddite; call me Grumpy… but I fail to see how dumping so much additional load onto an aged and insufficient energy grid, without first making firm plans to add new towers, lines, and generating facilities… is pure… shortsighted, is the polite term.

9 months ago

Dead EV’s can be rescued with tow trucks and taken to level 3 chargers or battery swap facilities.

Much cheaper and more efficent than a fleet of $100k – $200k evrescue trucks.

The proposed 30 mile range from a rescue charge is just a waste of time. You still need a full charge as well.

9 months ago

Just think, we have switched as a Nation to EVs. A major hurricane hits South Florida. After the people fleeing the storm get to about Jacksonville and the end of their range. Then what?
This will happen. Currently, the gas stations empty pretty fast under these conditions.

Warren G
9 months ago
Reply to  tom

Only about 1% of cars and trucks are EV’s at this point, so don’t understand that we have switched?

Rosalie Magistro
9 months ago
Reply to  tom

I’ll never own one.. They are worthless, except to maybe go to get groceries.

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