Hi Fronhofer, I’ve been wanting to try DC also and was thinking maybe your DC voltage was too low to work. 120vdc would only be equivalent to somewhere around 76vac. That would be below the 90v threshold of most devices. Any chance you are willing to try something higher!
Too low for what? Blowing out your charger? You can't feed DC thorough the HPWC. Doing so is an exercise in futility or stupidity; I'm not sure which. At best, nothing will happen. At worst, you'll destroy expensive electronics and maybe even start a fire.
This has bad idea written all over it. What are you trying to do, run a pair of 208V lines in series into your car to get 416V@32A? You realize that can't work, right (Ok, I know how to do it, but I'm not going to offer advice on destroying your car)? At best you'll blow a breaker when you connect phase one's hot to phase two's neutral (which is shared with all phases). If you somehow made it work and got 400+ volts, you'll likely fry your charger and be staying at the track longer than planned.
No, the hpwc doesn't have any rectifier in it. It's just a relay that opens/closes a switch.
I apologize I realize now what I said was confusing (will edit if I can), I was referring to the rectifier in the low voltage control circuit of the hpwc. It has an ac to dc converter that would likely happily operate on dc given it generally will pass through a rectifier stage. The relay and control circuit are usually all dc powered. At least this is how most evse are built and looking at the hpwc internals may have a similar layout.
Oh, I got you. You're talking about taking the AC from the wall circuit to create the little like 5V DC signals to use on its own circuit board, not talking about sending DC output on the charging cord. Yeah, that makes sense.
Well, sort of. I was saying the hpwc contains control electronics that are normally powered by AC from the plug. That ac is converted to dc to power the control electronics and relay inside the hpwc. So with that in mind if you fed the hpwc something around 160vdc it might run with no issues thinking it was running on 120vac.
Fair enough. Lots of wild and crazy charging ideas have been floated around on TMC over the years, many of which are wildly unsafe and gross NEC violations. I guess I've developed a bit of hypersensitivity to "creative charging thinking" as a result. I suppose it might be simpler to convert AC to HV DC (skipping the need for big transformers) if you can find a compatible inverter, but it still sounds risky if you don't know what you're doing.
There is a small DC supply (likely a switcher) in any EVSE to power the electronics. A linear power supply (with a step down transformer before the rectifier) will definitely not work with a DC input. Some switching supplies will. Just scanning through 5V switching supplies at Digi-Key, maybe 40% are spec'ed for HV DC input.
