That's great to hear that you have successfully demonstrated negative current via DCFC protocols! I've been speculating for decades that this should be possible, depending on if the car side would panic upon current lost versus expected current gained.
You say you have done 6kW, is this because the car freaks out above this? Or because you don't have a safe load larger than this to test with? It sounds like the trickiest part, if ignoring all the protocol negotiations, is that you need to be able to match the batteries high voltage in order to establish the DC connection. So a hypothetical PTO (Power Take Off) DCFC device would need to have its own power stage able to match the car. Very fun stuff. On Fri, Jun 28, 2024, 18:37 Cor van de Water via EV <ev@lists.evdl.org> wrote: > Essentially, you need to pretend to be a complete DCFC and then > "charge" with a negative current. > Cor. > > On Fri, Jun 28, 2024 at 10:09 AM (-Phil-) via EV <ev@lists.evdl.org> > wrote: > > > > I don't yet have any instructions, and it's very complex. You have to > > build hardware to generate and sense the 1khz 5% PWM pilot signal then > have > > a relay to switch the communications over to single-wire CAN, and then > > negotiate with the car's BMS over CAN. Once you have that working you > have > > to voltage-match the battery voltage on the port within a few volts > before > > it will honor your request to close the DC fast charge contactors. On > top > > of that, once you get all that working, you are left with pretty much a > > direct DC connection to the pack which can easily sink thousands of amps > if > > something goes wrong, so you have to really know what you are doing. > > > > Unfortunately, I'm not prepared to write up a how-to for this reason. > > Someone will either get killed, or damage their car, or both. Then > > there's still the problem of the warranty! > > > > On Fri, Jun 28, 2024 at 10:02 AM Barry Oppenheim via EV < > ev@lists.evdl.org> > > wrote: > > > > > Do you mind sharing the instructions or a link to the instructions? > > > > > > Thanks, > > > Barry Oppenheim > > > > > > On Fri, Jun 28, 2024 at 12:56 PM (-Phil-) via EV <ev@lists.evdl.org> > > > wrote: > > > > > > > I recently figured out a safe way to export power from any Tesla's > charge > > > > port. I got HV DC power export working from the port at around 6kW, > > > which > > > > could then be fed into an inverter for AC power. > > > > > > > > However, Tesla still instantly voids your warranty if you do this. I > > > have > > > > a salvage Tesla, so it doesn't matter to me, but it really dashes any > > > hope > > > > of offering a product. > > > > > > > > Tesla has always had this clause to void your warranty if "Using the > > > > vehicle as a stationary power source". (See: > > > > > > > > > > > > https://digitalassets.tesla.com/tesla-contents/image/upload/tesla-new-vehicle-limited-warranty-en-us.pdf > > > > ) > > > > > > > > I decided to see if they modified the warranty for the Cybertruck, > since > > > it > > > > has the AC power export feature built-in, and here's what they > changed > > > that > > > > clause to: (only for Cybertruck) "Using the vehicle as a permanent, > > > > stationary or long-term power source or backup". So Technically any > > > > "stationary" use still voids it! They also don't bother to define > what > > > > "long-term" is. (See: > > > > > > > > > > > > https://digitalassets.tesla.com/tesla-contents/image/upload/tesla-cybertruck-new-vehicle-limited-warranty-en-us.pdf > > > > ) > > > > > > > > I'm not a lawyer, but I don't think they can void your warranty > unless > > > they > > > > can prove your actions did the damage you are claiming under warranty > > > > coverage. (Per the Magnuson Moss Warranty Act, see: > > > > > > > > > > > > https://www.ftc.gov/legal-library/browse/statutes/magnuson-moss-warranty-federal-trade-commission-improvements-act > > > > ) > > > > Though that probably means they tell you to kick rocks and you > have to > > > > hire an attorney to fight them. I'd be interested in opinions from > any > > > > Attorneys on the list? > > > > -------------- next part -------------- > > > > An HTML attachment was scrubbed... > > > > URL: < > > > > > > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20240628/e3cf1c06/attachment.htm > > > > > > > > > _______________________________________________ > > > > Address messages to ev@lists.evdl.org > > > > No other addresses in TO and CC fields > > > > HELP: http://www.evdl.org/help/ > > > > > > > > > > > -------------- next part -------------- > > > An HTML attachment was scrubbed... > > > URL: < > > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20240628/e376d9be/attachment.htm > > > > > > > _______________________________________________ > > > Address messages to ev@lists.evdl.org > > > No other addresses in TO and CC fields > > > HELP: http://www.evdl.org/help/ > > > > > > > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20240628/e7fed405/attachment.htm > > > > _______________________________________________ > > Address messages to ev@lists.evdl.org > > No other addresses in TO and CC fields > > HELP: http://www.evdl.org/help/ > > > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > > -------------- next part -------------- An HTML attachment was scrubbed... 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