I bought a Chevy Volt Gen1 DC-DC Converter - Now What? Topic is solved

[arber333]

Perfect, thanks. I just tested letting the BMS get it running and then stop sending messages. I could tell the voltage dropped from the 14.x volts setpoint, and the flicker went away!
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Hm... cant you set BMS CAN rate in some menu? I think since you have everything wired it would be solved with minimum effort.

Also regarding precharge protection... DCDC goes ON only when both conditions are met: 1. 12V is sent to Enable pin and 2. CAN but telegram is seen in correct format and rate. This doesnt have to be in that order... so when you perform precharge if you use a relay to signal 12V to Enable pin when everything is ready you can send CAN telegram as much as you like, but DCDC will not turn on!

[Zieg]

so when you perform precharge if you use a relay to signal 12V to Enable pin when everything is ready you can send CAN telegram as much as you like, but DCDC will not turn on!

Good point, I suppose I could trigger said relay from the contactor + signal. Might be a moot point though, I don't see any options to adjust the CAN rate on my Thunderstruck BMS, so it looks like I need to use the teensy to control it. For testing I'm just programming the teensy to spit out its message whenever power is on, same as the BMS. Once I've verified everything is working, I should be able to alter the code to have it turn the DCDC on or off according to opmode. Or, heck, I wonder if I can map opmode to 0x1D4 with some clever gain/offset to have it control the thing directly? Might not be possible since it needs to send two bytes. Not sure if that's possible with regular mapping.

[arber333]

---- I wonder if I can map opmode to 0x1D4 with some clever gain/offset to have it control the thing directly? Might not be possible since it needs to send two bytes. Not sure if that's possible with regular mapping.

Well you can transmitt 0x1D4 telegram complete from the start with byte0 only turtning to A0 when opmode is correct.

[Zieg]

Oh, neat. How do you map byte 1? Just use some other arbitrary parameter that can be scaled to the right value and won't change?