openinverter forum

You are really making this hard. Show your params and spot values.

Did you change the timedelay?

Sorry Tom,
I thought I did change Timedly to "0" before my last post, but when I went to get the params and spot values, I double checked and realized it was still set at 10000. I reset it to "0" and then tried it again with the direct connections and "boom".... the 3 modules lit up and it started charging!!!!!

I know you're thinking... "you idiot, if you just listened to me you would have resolved this long ago". But THANK YOU once again!

I'll be updating my post here with what my final configurations and wiring was, as well as my own observations to discrepancies in the Wiki (eg. you can't use SimpCharge with the Tesla Gen 2 OBC).

For now, here are my current WORKING params and spot values. If you see anything still abormal about any readings, please let me know!

spiff wrote: ↑Sat Aug 02, 2025 1:28 pm I want to ensure I understand this completely:
The OBC pin A6 - AC present is an output signal that shows “GND” when it wants to charge?

So feeding this signal through a relay before it goes to the SimpBMS J5 pin 6 to turn it to 12V positive is what you’re saying it needs?

I'm now trying to wire this. I think I mis-quoted and it is OBC pin A1 (AC Present, OUT2) that I need to wire to. I measured the voltage of this pin when no power was applied, when 12V was triggered to enable charging on A3, and then when I connected the EVSE. Here's what I found:
When not connected or 12V was applied to A3, A1 measured 0V (ie. ground).
When EVSE was connected and charging, A1 measured around 0.3V.

Based on your description, I thought I might see it the other way around. Can you confirm if I'm seeing this correctly? I wanted to confirm this before I start wiring a relay to it.

A1 = OUT2 - AC present
Use an LED to be pulled to ground by the pin for easier diagnosis. Also you should not be measuring voltage but resistance to ground for grounding outputs.

Unfortunately it is possible the functionality of this has changed when Johu rewrote the code base.
It seems now to come on when the EVSE gets activated.

This now longer follows the logic I created originally of
1. Tesla Charger detects EVSE is inserted
2. Pulls A1- AC Present to ground
3. BMS checks cells and temperatures then provide the Enable to Pin A3
4. Charger enables and requests HV via A6 HV Request

What it does now:
1. Tesla Charger detects EVSE is inserted
2. Required A3 Enable to be 12V
3. Timedly to have passed
4. Charger enables and requests HV via A6 HV Request
5. Charger enables EVSE and A1 - AC Present

This now means you need to use A6 into the Vero-BMS, ask Reider to tell you how to use the Tesla Charger im sure other have too. Likely they will need to implement the CAN control logic.

Thanks Tom (again).
So I did follow up with Reider and he confirmed (at least for the Vero BMS) that in order to do CAN control, it requires hardware v 2.3 and unfortunately I have v2.2.

But he did confirm that I should use A1 from the Tesla OBC and use the relay as you originally suggested. I went back today to re-test and it is following the behaviour both of you described (A1 goes to ground when power/signal 12V is applied to A3 to start charging).

I also measured that A1 nominally has ~3-4V when sitting idle (12V on B1, nothing on A3).

So my final question here is on the following behaviour:
Should A1 go to ground when A3 is triggered (provided 12V) or only when the EVSE is actually connected? The way my setup operates now is that A1 goes to ground when A3 is triggered and stays grounded when the EVSE is connected and charging. Is this correct?

Thanks again!

spiff wrote: ↑Thu Aug 07, 2025 2:19 amIs this correct?

I have no experience with the V5 software for the Tesla charger

tom91 wrote: ↑Wed Aug 06, 2025 7:34 am What it does now:
1. Tesla Charger detects EVSE is inserted
2. Required A3 Enable to be 12V
3. Timedly to have passed
4. Charger enables and requests HV via A6 HV Request
5. Charger enables EVSE and A1 - AC Present

This is derived from reading the software. You need to use a load going to ground on the pins to determine if they are actually switching.

Progress!
So I finally was able to get the charger to charge the battery with the BMS!!

I noticed and confirmed the following things (with the help from Reider at VeroBMS):
1. When the EVSE is plugged in, it triggers A1 to go to ground (more or less, more on this later).
2. The BMS logic waits for AC Present from the OBC pin A1 via the relay to check the setpoints and pre-conditions are ready to charge.
3. Once it confirms, it sends the 12V to pin A3 on the OBC to begin charging.
The issue I saw was that when I plug in the EVSE, pin A1 on the Charger goes from about 3V to about 0.3V and doesn't drop to 0V. Measuring resistance still shows high ohms in this case. So it's not enough to trigger the relay to send the 12V signal to tell the BMS that AC is present.

So what I did just to test this was:
1. Plug EVSE in.
2. Directly send 12V to the BMS pin expecting AC present (mimicing the relay working).
3. Connect 12V to pin A3
4. Charging starts.

Does anyone know if A1 dropping to only 0.3V or not zero Ohms is expected? It's definitely lowering from the at-rest state of about 3V.

This is the last thing to allow the system to work as intended. In the meantime, I can still finally charge the battery and monitor balance, temps, etc!!