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Realized our old RV's 30-amp plug could probably charge the car too

We've got a camper parked next to the garage with its own TT-30 pedestal that just sits unused most of the year. Finally wondered if I could run the car off that instead of waiting on an electrician's quote for a real install. Plugged in a dogbone adapter I had for camping and left it overnight -- woke up to way less charge than I expected, maybe half what the app estimated going in. Looked into it after and apparently TT-30 is only rated for 24A continuous even though the breaker says 30, and I think my adapter might be undersized too. Anyone actually running a car off their RV outlet long-term, or is this one of those things that works in a pinch but isn't worth relying on?
Filed under: RV & Road Trip Charging
013 answers
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13 ANSWERS
vinnie_carbone
@vinnie_carboneOctober 03, 2026
TT-30 is a 120 volt outlet. Only the 50 amp RV pedestals give you 240. So you were doing Level 1 overnight, not anything better. What is on the other end of your dogbone? If it goes down to a regular household plug and you used the cord that came with the car, the cord only pulls 12 amps no matter what the outlet is rated for. 12A at 120V is about 1.4 kW. On my Leaf that works out to roughly 4 miles of range per hour.
greg_whitaker
@greg_whitakerOctober 06, 2026
TT-30 is 120V. That's the whole story right there unfortunately.
rhenley_64
@rhenley_64October 07, 2026
Well that's embarrassing. I saw 30 on the breaker and my brain just filled in the rest. Guess I'm back to waiting on the electrician.
mdonnelly_
@mdonnelly_October 07, 2026
Some of that missing charge is just L1 being inefficient too..... I measured roughly 21% loss on 120V vs about 8% on my JuiceBox 40 at 240. So the app's estimate and what ends up in the pack aren't the same number, and in CT in January it gets worse. Even a 24A 240V setup on that existing wire would be a big step up!
rgalloway
@rgallowayOctober 07, 2026
Before you spend anything, I'd find out whether L1 is actually a problem for you. I paid $3600 for my 14-50 - the panel is on the opposite side of the house and the electrician had to rewire a good chunk of the basement to reach the garage. It's nice to have, but most weeks my normal driving would have been fine on a wall outlet. If your daily miles are modest, 12A overnight might cover it most of the year. And if it doesn't, at least you'll know what you need when someone finally shows up to quote it. I wouldn't keep leaving a camping dogbone plugged into an outdoor pedestal every night, though.
cody_ratliff
@cody_ratliffOctober 07, 2026
Ran our first EV on 120 for about four months before the outside EVSE went in. Fine around town. As soon as we took a longer trip it couldn't catch up.
mbrannigan
@mbranniganOctober 07, 2026
For what it's worth I've been on 12A 120V with my Bolt EUV for a couple years in the Chicago area. It works fine for daily driving – it's only a problem after a long trip in winter.
bhollister
@bhollisterOctober 08, 2026
I've charged at 240V 16A for a long time and never needed more. 24A on that wire is plenty for most people.
gpetersen
@gpetersenOctober 10, 2026
When the electrician asks what the outlet is for, say a welder. I got quotes for the identical 14-50 both ways. The ones for "an EV charger" came in at double. Same wire, same outlet, same everything.
gpetersen
@gpetersenOctober 10, 2026
And it's still a welder.
wadecross
@wadecrossOctober 11, 2026
Welder thing works. Bought the 14-50 and breaker myself, told the guy where I wanted it and never said the word truck. About $85 on a 200A panel. My buddy said Tesla on the phone and got quoted $1800
Marcus Chen
@Marcus ChenVerified ExpertOctober 11, 2026
Careful with the welder thing. Code treats welder circuits and EV circuits differently: welders can be sized for their duty cycle, but an EV charger is a continuous load and has to be sized at 125%, and EV receptacles need GFCI protection. If you hide what it's for, you could end up with a circuit that's legally correct for a welder and wrong for a car that pulls full current for 8 hours. If the quotes are inflated, get more quotes, but tell them it's for an EV.
rhenley_64
@rhenley_64October 15, 2026
Took the cover off the pedestal out of curiosity. The wire going in is pretty thick and the breaker at the panel end is a single pole 30. No idea if that tells anyone anything.