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DC in Tesla Level 2 Charging?


100 µW
Feb 2, 2022
So, most electronics will accept 340 VDC (or 170 VDC) input and pass it through the rectification stage with a slight loss because of the diodes but have no problem using it. I've successfully done this with TVs, Apple TVs, computers, and more. It just works. I've yet to find anything other than AC (only) motors that have any issue with this. I've even powered my welder directly.

What I'm interested in, is if anyone knows of anyone that has or has looked at the schematics and can tell if there is anything that would prevent you from using the OpenEVSE Level 2 charging or other projects and instead of providing 240 VAC provide 340 VDC using the same protocol (i.e. not DC Fast charging) so that the Tesla (and other) internal boost converter would then take that in and bring it up to the car battery. (DC charging skips the internal boost, and is done at the charger, which is vastly more complex and harder to get documentation on aside from part 2 of this question)

The reason for this is that I would really like to be able to charge a Tesla or other EV directly from Solar/LiFePO4 battery. I.e. I have a 48/96/128/240/320 VDC battery and I'd like to be able to skip the inverter (and the cost and inefficiency) and charge it directly DC => DC and have the car step up the voltage.

My theory is that if the car got 170 VDC or 340 VDC (I would assume that it might freak out and shut down the charging if it got anything outside of the 170 (level 1) or 340 VDC (level 2) ranges, but maybe it would just work from 112 - 350 VDC like most TVs etc will, don't know?) in and the right signals for Level 2 charging, that it would "just work".

If this did then the only part required is to step up the voltage of the battery to 170 VDC or 340 VDC and say 40 amps with a half-bridge boost converter at like 98%+ efficiency and way less money. (And if it works like a universal converter and would handle 80-250 VAC and thus 112-350 VDC, then for most of the battery ranges I'm looking at it wouldn't need any conversion at all)

Anyone tried this or have information about the design of the PFC stage that rectifies the AC power in the Tesla/others that might lead to an answer?

Basically, looking to confirm that Tesla isn't doing any special, just on a much larger scale (22kw versus maybe 1.2kW out of a power supply for a computer). Because if it is what I think it is, there is a huge opportunity to improve the efficiency of charging from solar/wind/batteries for EVs.

Interesting idea. It might work. Not sure if the car charger will care if it is getting DC instead of AC, but I suspect not. I don't really want to try it on my own car though. You might be able to look at some of the numerous Tesla teardowns on Youtube to find the charger topology.