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Comment by SoftTalker | Hacker News Reader

But using two outlets, on opposite phases, would give you double the voltage. Might be too much to expect people to identify two suitable outlets and have a “Y”extension lead that would bring them together.

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Somewhere a copy of the NEC is bursting into flames.

You'd be better of installing a new circuit with proper equiptment. Most homes would be able to at least accommodate a 20amp 220v socket, which takes about 40% of the charging time of a regular socket (15amp 110).

OTOH I see no fundamental reason that one couldn’t build an EVSE that connected to two different outlets and drew from both of them. Two branch circuits supplying the same device is not especially rare.

I've never seen that. With the right protection circuits it could work safely. However, most garages seem to only have one branch anyways, so might as well add a 20amp+ 220v branch.

If either circuit had arc fault or ground fault (or both) it would trip if you tried drawing power from both. Which is going to include pretty much any plug outside or in a garage in the past 30 years.

Yes, it'd create a multi-path circuit causing the trip.

This (multi-path circuits) is not uncommon when homeowners try to wire up a smart switch requiring a neutral to a switch-circuit without a neutral (as most light switches actually only need to switch the hot) and so they "borrow" a convenient neutral from a neighboring circuit which causes it to immediately trip!

In a (large, recently constructed) garage, it seems likely that you've got multiple circuits with outlets. If you've got multiple outside outlets, they're probably all on the same circuit. If the hots are the same phase, I don't know if there's a way to determine if they're behind the same breaker or not. If the hots are on different phases, you need to return to each neutral or the gcfi that's likely to be present on an outdoor outlet will trip.

>I don't know if there's a way to determine if they're behind the same breaker or not.

Turn the breaker off and plug something in and see if it turns on

Well yeah, but it'd be a bad idea to make a charger with two 120v plugs, because chances are people will plug them both into the same circuit.

I'm not defending the idea of using two out-of-phase 110V circuits, but... this theoretical EVSE could detect its two inputs not being out-of-phase, blink its red "110V only" light, and only use one of the inputs to charge at 110V instead of 220V.

I’ve seen carpet cleaners where their machine had two 120v cords that needed to be on different breakers

If you are going to that effort do a 220v with a 60amp, should cost almost the same but is typically the top of level 2 charging specs.

Yeah, I put 20amp because the higher amps are nice, but many panels aren't going to handle an additional 60amp circuit (and be NEC compliant). Most panels should be able to handle an additional 20amp circuit though.

Any outlet that is safely usable outdoors will have a gfci, and using two outlets on different phases would be indistinguishable from a ground fault.

That product exists, and it's called Quick220.

The Y extension lead would work, except that if either outlet has line and neutral swapped, you have a dead short, and if you pull one of the male ends while charging, you have a live male prong.

Quick 220 mostly resolves this, but you still need a 3 lamp tester, IIRC.

https://hackaday.io/project/4818-a-quick-220-clone

https://quick220.com/

Many (if not most) residential electrical in North America is split-phase, not multi-phase. This is why residential high-power sockets are usually 240V, and industrial 2-phase is most often 208V.

There is a big carve out in your residential is 240 rule. A lot of apartment buildings have two phase and are also 208.

Why are you spit-balling bizarre and dangerous fixes to an already solved problem?

A certified electrician will know how to cable up a higher-capacity appliance such as an electric oven or level 2 home EV charger.

>> Why are you spit-balling bizarre and dangerous fixes to an already solved problem?

Darwin Awards don't just win themselves, you have to be creative about it, right?

Seriously. It's wiring up a dryer outlet. Takes very little work if the breaker box is nearby, to do it the right way.

My partner and I did it in less than a day in conduit in our garage. No jury rigging necessary.

My EV charging, at 32A, draws more power than the rest of the house combined at peak load. The battery capacity is also equivalent to the house's max power usage for an entire day. Even when the low temperature is 90F/32C.

I hired an electrician to come out and install the 240V 50A circuit. I'm sure I could've, but our local code requires it, I don't want our insurer to deny our claim if something goes wrong. I, obviously, think people should be pretty careful with 10kW (or more) continuous load for hours at a time.

I definitely don't think people should lean on janky solutions that are technically feasible when it comes to EV power.

you must be driving great distances if you're charging at 32A?

i've got 240V 40A and I trickle charge at at most 10A overnight, and it's way way beyond adequate. i don't drive super far daily...but easily could still.

At the moment, I'm WFH -- charging at 32A lets me utilize my solar panels instead of selling the energy to the power company at a discount and then buying it back at full price. It's also a bit more efficient, since the car's electronics consume 300W continuous during the charging process, which means shorter charging times use less total power.

But as I mentioned in my comment way above, 120V12A works, but 240V32A is notably more convenient.

yep, agreed. didn't realize the power company pricing dynamics would make it preferable: that's interesting!

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