Out at a log cabin this long weekend, and using a combiner cord turned one twenty hour trickle charge session into 10, and another 30 hour session into 15. 240v at 12 amps is surprisingly useful.
Something like this: https://www.amazon.com/Parkworld-Combiner-Household-Generator-Receptacle/dp/B076ML3MXK
Sorry if I'm a bit slow. We have 240 V everywhere here in Oz. You used this cord to combine two 120 V power sources to produce 240? Doing that increased your charge rate?
I built mine, but here’s a commercial one: It’s instructions: https://docs.google.com/document/d/1d1qhmIyfPAg-nwqJnnUTWtIq3PnKfD7MazijqE_NifE/mobilebasic works by combining two out of phase 120v feeds to make 240v, charging via the granny charger at 2.8kwh vs the normal 1.4 on 120v
It's only possible to do this because of the unique alignment of all these "stars" in the N. American market: a) The Hyundai portable charger internal switch-mode power supply and relays seem to handle 240 VAC, even if the box is marked "120 VAC only". But, it's unlikely to be UL-approved at higher voltages, for whatever that's worth. The Tesla portable unit is one that is designed for multiple voltages and currents. b) Portable chargers only set the current offered to the EV, not voltage or power. Double the voltage and you double the power. c) N. American domestic power is 240 VAC 'split phase' and 120 VAC power outlets are placed somewhat equally on both phases around the house. You just have to locate one outlet on each phase because 240 VAC is present across the two "hot" pins. You don't use the neutral pins. (This may not be exactly the same in a commercial or multi-unit property that has a 3-ph supply) Just for a laugh I tried powering my NZ/AU 230 VAC 6/8 amp portable charger on a 120 VAC transformer and it indicated an error.
It's also worth noting that these won't work (or shouldn't work, rather) on GFCI circuits, and that doing it this way without a box with protection circuitry in the middle (for accidental unplugs of one phase, making sure you have both phases, and other shenanigans) is very much an "at your own risk" thing. But in a pinch it does work.
