openinverter forum

Digging through the electronics modules from the battery, I found the precharge circuit. I found it interesting because it uses PTC thermistors.
The PTC's are C1412by TDK rated for 620V and 120ohm. The relay is V23700-C0001-A408 made by TE Connectivity 450V and 20A.

The PTC's are arranged in 2S7P making it a 34.3 ohm precharge resistor.

If there is a short on the HV when precharging the PTC's will dissipate 4700W @400V 11.7A. This will heat up the PTC's real quick, and that will lower the current. A normal resistor will not survive for long in this situation.

EDIT: turned out with the closing loop I used I put red to white and black to black. Without realising when I wired it I assumed all TxN and RxN would be on same row but the flip TxN to second row. So with that fixed and wiring check I get 0x21 response

I am really struggling to get this functioning on the bench. Can someone please give me some insight into how to "terminate" the bus with these modules?

I have the M3/MAX BMS from Damien, https://github.com/damienmaguire/Tesla- ... M32_M3_Bms

I am spitting out the SPI as per data sheet and doing the UART chain init, however no RX Status 0x21 is recieved I keep just getting 0x11.

I have made sure SPI works by requesting other register info.

Could someone scope a working RX and TX pair for me to check if the signal is shaped properly.

I can even see the signal going into the module coming out. So in on pins 1+7 and out is 6+12.

Got it now to initialize the string and read out the single module voltages and temp registers.
Currently have a slight issue with the temp register so will dig through others example code to find what I am doing wrong.

Likely due to this:

VWJoe wrote: ↑Mon Aug 22, 2022 7:57 pm Now onto the cell temperature sensors. each module has three NTC and are not contacted as the MAX chip manufacturer recommends.

This thread is a goldmine of information.

Edit: I am using the Hyndai/KAI Arduino base code to port from.

Anyone written code to read the PSA modules? Otherwise I will write the code to do it and publish it to Damiens github once i got all read outs working.