openinverter forum

Thanks for starting up that old thread P.S.Magelsdorf!
I did get another BECM and can read cell voltages and temps now. The real problem was that I didn't have my pack fully connected together. The new BECM was still showing modules with 0 volts until I reconnected all the modules back together. My previous BECM might still be ok, but I haven't hooked it back up to test.

Hi, I wonder if it is possible to configure SimpBMS to show all voltages in x.xxx format in the serial monitor? It is x.xx format by default in Tesla BMS code. Or is that too fine and 3rd digit after the comma does not matter?

You can change a setting to show it, in the debug menu.

Can this type of contactor be used on 12V switched output?

VW 3Q0915646B
Non Economiser Type Current Draw 0.556A@12.8V

I would not recommend it, the contactor will get hot and possibly the 12V output chip will heat soak and start cycling the output.

Has anyone used the VoltBMSV2 code yet? My Simp was constantly restarting because the watchdog wasn't updating. I got it to "work" by commenting out the cleartime block of the main loop, but I'm wondering if this version of the code is still in progress. It's possible I just don't have the settings configured properly, but I'd love to know if the code "should" be working as is.

Hi, I have hooked up SimpBMS with Tesla BMS boards to a 108s battery. Got all voltages reported. Just tried to do some balancing and I'm a bit puzzled as the BMS took down all cells by ~5mv overnight but delta remains the same at ~21mv. I have set balancing voltage hysteresis to 4mv just to get all cells balanced. Is there a setting that I missed or is there something wrong?

Another question. Would it be possible for SimpBMS to switch on only dcdc non economised contactors upon ignition? Which inputs should I use?

m.art.y wrote: ↑Fri Sep 08, 2023 11:04 am I have set balancing voltage hysteresis to 4mv just to get all cells balanced. Is there a setting that I missed or is there something wrong?

What level is the pack at and is it above the balancing threshold, also which mode are you in?
For "EV mode" balancing happens in the "Ready" and "Charge" state, for "ESS mode" it always balances

m.art.y wrote: ↑Fri Sep 08, 2023 11:04 am Another question. Would it be possible for SimpBMS to switch on only dcdc non economised contactors upon ignition? Which inputs should I use?

The way the contactors switch is listed in the manual, the high side and lowside contactor outputs work at the same time.

tom91 wrote: ↑Mon Sep 11, 2023 9:49 am What level is the pack at and is it above the balancing threshold, also which mode are you in?
For "EV mode" balancing happens in the "Ready" and "Charge" state, for "ESS mode" it always balances

Yes I have reduced the balancing voltage setpoint just to try and balance the cells, I was in ready mode and serial interface said balancing was active. I have now realized the reason all cells went down by around same ~4mv overnight was not because balancing took them all down but it seems that the tesla balance boards consume some energy from the cells. Can see a LED on the Tesla slave boards blinking despite if the 5v supply/SimpBMS is connected or not. I'm a bit surprised by the current consumption of the tesla boards and wonder if there is any way to switch this off?

m.art.y wrote: ↑Mon Sep 11, 2023 10:23 am Yes I have reduced the balancing voltage setpoint just to try and balance the cells, I was in ready mode and serial interface said balancing was active. I have now realized the reason all cells went down by around same ~4mv overnight was not because balancing took them all down but it seems that the tesla balance boards consume some energy from the cells. Can see a LED on the Tesla slave boards blinking despite if the 5v supply/SimpBMS is connected or not. I'm a bit surprised by the current consumption of the tesla boards and wonder if there is any way to switch this off?

Yes by not talking to them, also the balancing current is very very low like a 100mA at most so balancing takes a long time.

What is the max. current that the SimpBMS can source on pins J5:3 and J5:8? In the datasheet it's used to power the display. Looking to power @muehlpower's CCS volt sense board from the same pins too.

alexbeatle wrote: ↑Tue Sep 12, 2023 8:21 pm What is the max. current that the SimpBMS can source on pins J5:3 and J5:8? In the datasheet it's used to power the display. Looking to power @muehlpower's CCS volt sense board from the same pins too.

J5:5 - 5V power should be limited to a draw of around 250mA. J5:3 and J5:8 are serial lines which are connected directly to the teensy so they cannot provide any power.

I'm trying to compile a revised version of the Volt BMS code (thanks to amsmntparks), and I'm running into a library issue. Specifically, my Arduino IDE can't seem to find freeRTOS, which is referenced in one of the ESP32 libraries that is referenced in one of the BMS libraries. I've downloaded every possible version of FreeRTOS that Arduino's library manager has, and the issue persists. Does anyone have a version of the freeRTOS library that will work?

EDIT: I'm trying this on another computer, and have hit a different weird issue. It says that the config.h file doesn't exist, but it is definitely in the folder. Any ideas?

Not sure about the freeROTS issue, but rename your config.H to config.h and it should work. I don’t think GitHub picks up the case change when you commit but Arduino does. I’ll force a fix when I’m back home at the end of the month

Ok I got a new strange error code:

Compilation error: 'unsigned char Serial_CAN::exitSettingMode()' is private within this context

Full error result attached. (too large to put into post)

P.S.Mangelsdorf wrote: ↑Thu Sep 14, 2023 2:17 pm Ok I got a new strange error code:

Compilation error: 'unsigned char Serial_CAN::exitSettingMode()' is private within this context

Full error result attached. (too large to put into post)

Ya, I opened an issue about that. The exitSettingMode() method in the Serial_CAN library needs to be set as a public method. There might be a more elegant fix, but I just edited my local copy of that library.

P.S.Mangelsdorf wrote: ↑Thu Sep 14, 2023 11:47 am I'm trying to compile a revised version of the Volt BMS code (thanks to amsmntparks), and I'm running into a library issue. Specifically, my Arduino IDE

Please do not post about this in this thread but create a spin off. This is not original SimpBMS firmware released by myself.

Great to see other contribute with support for Chevy Volt Gen 2 packs, but this is a completely different approach then used on all other applications of the "SimpBMS", using OEM Cell Monitoring Boards.

tom91 wrote: ↑Thu Sep 14, 2023 3:20 pm Please do not post about this in this thread but create a spin off. This is not original SimpBMS firmware released by myself.

Great to see other contribute with support for Chevy Volt Gen 2 packs, but this is a completely different approach then used on all other applications of the "SimpBMS", using OEM Cell Monitoring Boards.

Apologies. Had posted here as it seemed more generalized than that spin off.

Also just to note; the new Gen2 version is using the OEM cell monitoring boards, just with the battery control module still in place.

tom91 wrote: ↑Thu Sep 14, 2023 3:20 pm Please do not post about this in this thread but create a spin off. This is not original SimpBMS firmware released by myself.

Great to see other contribute with support for Chevy Volt Gen 2 packs, but this is a completely different approach then used on all other applications of the "SimpBMS", using OEM Cell Monitoring Boards.

Sorry Tom. We’ve moved it to DMs. For what it’s worth, these issues all apply to the unmodified version of the code as well.

amsmntparks wrote: ↑Thu Sep 14, 2023 4:05 pm Sorry Tom. We’ve moved it to DMs. For what it’s worth, these issues all apply to the unmodified version of the code as well.

Correct as the library used is also in my github, having libraries work across all variants of arduino IDE and such is a pain. Best to stick to the compiled HEX files. Unless you are making major changes, does however mean you need to verify all the correct libraries and functioning.

Hi, on Teensy 3.2 based SimpBMS with Tesla code when IN1 (pin17) is driven high the SimpBMS enters into Drive mode as shown on the serial monitor. But for some reason it also still says balancing active on the serial monitor. I'm in EV mode, ESS mode is set to 0. Why that might be? It should stop balancing in Drive mode according to the manual. Is there any other pin that should be driven but it is not to stop balancing?

m.art.y wrote: ↑Fri Sep 15, 2023 3:13 pm Hi, on Teensy 3.2 based SimpBMS with Tesla code when IN1 (pin17) is driven high the SimpBMS enters into Drive mode as shown on the serial monitor. But for some reason it also still says balancing active on the serial monitor. I'm in EV mode, ESS mode is set to 0. Why that might be? It should stop balancing in Drive mode according to the manual. Is there any other pin that should be driven but it is not to stop balancing?

Probally not written the code propper to stop actually change that state, it will just balance and then timeout or get stuck balancing. Yet the logic for balancing is behind this and always looks at the input parameters and lowest cell voltages to determine what to balance.

tom91 wrote: ↑Fri Sep 15, 2023 5:51 pm Probally not written the code propper to stop actually change that state, it will just balance and then timeout or get stuck balancing. Yet the logic for balancing is behind this and always looks at the input parameters and lowest cell voltages to determine what to balance.

Thanks. So if I'm not controlling contactors with SimpBMS I may as well not bother with the KEY IN input to enter into drive mode and just leave the BMS in Ready mode when I'm driving as well?

m.art.y wrote: ↑Fri Sep 15, 2023 7:33 pm Thanks. So if I'm not controlling contactors with SimpBMS I may as well not bother with the KEY IN input to enter into drive mode and just leave the BMS in Ready mode when I'm driving as well?

Yes no need to switch. it will keep outputting the CAN bus info.

Hi, another question. Are the TX and RX signals for the Nextion display the same as the TX and RX in the usb socket? My intention is to use usb TX and RX for the serial monitor and also for the Nextion display. Would that work if I provide 5v and ground for the display? Thanks