Charging with an inverter generator - success!

I had purchased all the necessary adaptors to get my Honda EU300i connected to my truck for charging, so I figured I'd try it out before I actually needed to use it.

Hooked up the NEMA L5-30P to TT-30R adaptor to the generator, then plugged that into the TT-30P to NEMA 14-50R adaptor, then plugged in the Rivian portable charger using the NEMA 14-50P connector.

Fired up the generator and eventually the lights on the Rivian charger started pulsing red, indicating an error. Assumed it was a ground issue. Tried making my own grounding cable which I staked into the ground and tied to the ground lug on the generator; still no love.

Found reference on this forum to a neutral-ground bonding plug. Sure enough, others say that my generator, along with a lot of inverter generators, use a floating ground. The solution is to use a neutral-ground bonding plug.

Looked up what that was and made one in about 1 minute. It's that easy. Just take a normal 120v/15a plug and jumper between the neutral leg and the ground. That's it. Can make one yourself from a cut electrical cord with the white/ground wire nutted together (hacky and potentially unsafe if you aren't confident in which wire is what, easily tested using a multimeter/test light though), or use a replacement plug that opens with screw/clamp style terminals like this with a 1" piece of 12ga wire jumpered between the neutral and ground. I opted for the second method since I had a 120v/15a plug on the end of a custom extension cord I wasn't using anymore.

Plugged that in to one of the 15amp outlets on the generator, fired it up, and BOOM, white light on the Rivian charger. The bonding plug is the orange plug with no wire plugged into the generator in the photo. Plugged it into the truck, set the charging amps to 20 (max on my gen outlet is 21.7amps) and she was charging like a champ. I was able to sneak it up to 22 amps and nothing complained. I was teetering between 3 and 4 mi/hr of charging, 3kw, which is completely expected.

I'm going to try a measured 1-gallon fill on the generator to see how much charge that will get me in real life vs estimated consumption/kWh, if that's something everyone here would find helpful. I'd sure like to know. I'm also pleasantly surprised on how quiet this generator is, even running at full song/max output. It never surges/drops either, even with "eco throttle" enabled. Just nice steady smooth output.

Honda generators have been renown for being quiet. I've a Honda eu1000 and Honda eu2000 (the 2000 is the quieter). I haven't needed to use them to recharge an automobile, but did use one to power a electric golf cart who's lead/acid batteries drained way faster than I expected one snowy (and cold) winter day.

Great job! I'd be interested to know what the "MPG" would be for the generator.

Keep us posted! Been wondering about this exact setup for some trips down to Baja.

I'm very interested in this. I got a harbor freight 3500 watt inverter generator. Direct competitor to the Honda quiet one you have. Like the 300i it has 30 amp RV outlet. Were you able to bump it up to 20 amps? Any higher? For some reason I thought we could only do 15 on a 110 outlet, and the truck wouldn't allow a higher amperage...

Oddly enough I have a 110 to 220 converter I bought to power my well water pump on this generator in case the power went out so I was gonna use that to convert the 110 30 amps to 220 but if we can dial up the amperage within the vehicle then I don't need that.

Operator said:

I'm very interested in this. I got a harbor freight 3500 watt inverter generator. Direct competitor to the Honda quiet one you have. Like the 300i it has 30 amp RV outlet. Were you able to bump it up to 20 amps? Any higher? For some reason I thought we could only do 15 on a 110 outlet, and the truck wouldn't allow a higher amperage...

Oddly enough I have a 110 to 220 converter I bought to power my well water pump on this generator in case the power went out so I was gonna use that to convert the 110 30 amps to 220 but if we can dial up the amperage within the vehicle then I don't need that.

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You can charge at a higher amperage by using the 14-50 adapter for the portable charger rather than the 5-15 adapter. You’ll need an EV specific adapter from whatever 30amp/120v plug is on the generator to a 14-50.

Rasputin said:

Keep us posted! Been wondering about this exact setup for some trips down to Baja.

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It’s worked on every inverter generator I have tested. The charge rates aren’t fast and the fuel consumption is pretty high but it’s better than nothing if you need it.

Thedude said:

You can charge at a higher amperage by using the 14-50 adapter for the portable charger rather than the 5-15 adapter. You’ll need an EV specific adapter from whatever 30amp/120v plug is on the generator to a 14-50.

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Thanks dude. My first ev, and all the charging / voltage options / connector names can be a bit overwhelming diving into it.

TheIglu said:

Plugged that in to one of the 15amp outlets on the generator, fired it up, and BOOM, white light on the Rivian charger.

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I have a 9000w generator and I tried multiple things including the bonding plug. I could get my 110v to work but couldn’t get the 220v to work. I would very much like to know how to get that to go. That way I would get more than 2 miles of charge and hour while burning a gallon of gas an hour. Thoughts?

W1SE said:

I have a 9000w generator and I tried multiple things including the bonding plug. I could get my 110v to work but couldn’t get the 220v to work. I would very much like to know how to get that to go. That way I would get more than 2 miles of charge and hour while burning a gallon of gas an hour. Thoughts?

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When you plug in the charger to the generator what do the status lights on it do?

Thedude said:

When you plug in the charger to the generator what do the status lights on it do?

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On the 220 plug It’s been a few months but I believe it goes green for a bit then red. I think I will have to try a ground-neutral bond on another 220 plug of make a special 2-plug bond between both side of the 220 split off (1 on each 110 plug) to put a ground on one plug and neutral in the other. I can’t see how that would matter but who knows. I get a little scared messing with electricity going into the truck. Lol

W1SE said:

I have a 9000w generator and I tried multiple things including the bonding plug. I could get my 110v to work but couldn’t get the 220v to work. I would very much like to know how to get that to go. That way I would get more than 2 miles of charge and hour while burning a gallon of gas an hour. Thoughts?

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What type of outlet jack do you have on the generator?

On my 7500W Honda I get 16 hours out of 5 gallons at full output, so assuming 30 amps is about 15mph, that's about 48mpg. Not too bad for a pretty backassward setup.

I get about 14mph on 34 amps to an actual EV charger, not a generator, so I'd estimate closer to 10-12 for 30 amps.

TheIglu said:

I'm going to try a measured 1-gallon fill on the generator to see how much charge that will get me in real life vs estimated consumption/kWh, if that's something everyone here would find helpful.

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I'd be super interested in this. My back of the envelope math puts the 3000i at around 13mpg at peak load on the generator. I'd guess 10mpg is more realistic in practice.

Not great in absolute terms but pretty decent when you consider how suboptimal the charging regime is.