Tesla DC/DC Charger Project?

Topics concerning the Tesla front and rear drive unit drop-in board
Post Reply
JohnGalt1717
Posts: 1
Joined: Tue Jul 26, 2022 9:40 pm

Tesla DC/DC Charger Project?

Post by JohnGalt1717 »

Hi there, I'm approaching this differently but it appears that the information might be close to able to make this happen.

Basically I'm off grid. At most I have grid for backup. Most of the time I'm using a large (120kW) LiFePo4 battery and LOTS of solar panels. My house is truly off grid because we use geothermal heating and cooling too. We have a model 3. So that means it's going DC to AC (87-92% efficient at best in real world + cost of inverters you don't need) and then AC to DC (95% efficient MAX) for a total power loss of about 10-15% real world plus the cost.


What I'd like to do (and what EVs should be doing in the first place IMHO) is create a wall charger that has the PFC and then DC/DC converter in the wall charger and then talk to the Tesla and do DC "fast" charging but I want the wall charger to limit the power to what I have excess etc. (my problem that doesn't have anything to do with the car really)

So what I want to do is build 2 separate PCB designs using an STM32 micro controller:

1. AC to DC with PFC and DC/DC boost converter. This will be the same as what's in the car but on the wall. To me this is what the standard should be for AC charging at home etc. There's just no reason for AC power to be going into the car at all because a 40A portable unit is trivial and a wall one even easier.

2. And second PCB that has nothing but the logic to talk to the car DC/DC and a boost converter (and for high voltage batteries that get over 400VDC a buck option).

Basically, the difference between the two is that the former has a PFC in it, and the later, does not.

Then

This would take up to X amps in and whatever incoming voltage (i.e. 48VDC and say 200A) and step it to what the car wants, tell the car what it can deliver etc. using the communication over the Tesla protocol and do DC/DC charging bypassing the AC/DC charging in the car. (I'm aware that it is technically possible to feed DC using the AC standard which is easier to work with, however that would likely burn out the PFC in the car in short order unless someone knows how to get the car to do the boost/bucking with DC using the trivial PWM protocol used in normal wall chargers which would probably be ideal)

Does anyone have any docs on how to do this? Obviously if there is a way to get the Tesla to accept DC while using the PWM signal used for AC I'd love to just do that as long as it isn't running the DC through the PFC. Otherwise, I'm looking for good documentation on the Tesla Canbus protocol for DC/DC charging and if anyone has a working Tesla DC/DC charger prototype?

Thanks,

(Yes I'm very good with micro controllers and building boost/bucks and have my own MPPT controllers, inverters and BMSes running, so I know what I'm doing)
pigwet
Posts: 1
Joined: Tue Oct 25, 2022 1:32 am

Re: Tesla DC/DC Charger Project?

Post by pigwet »

Any progress on this? I'm an EE and wish to do the same.
Post Reply