openinverter forum

Hi Forum. I have several 16 cell battery packs which have bms modules fitted which are daisy chained using the bq76PL455A-Q1 chips. Has anyone managed to comms with these? If so do you have Arduino code you are willing to share please? Thanks. Peter

Literally you can talk to the chips using the standard protcol, TI even release a demo board and software to get you started.

little bit of google gives me this: https://github.com/dmwahl/BQ76PL536A-Ar ... ent-Shield

Thanks Tom91. I am working my way through that, downloading the files and hopefully see a result Keep safe. Peter

We have developed a unit to talk to these. Its not as simple as it seems. The implementation is not exactly as the Texas information would have you believe. We are now into production of version 2 of our Pack Monitoring unit, that not only has 4 discrete dry contact outputs as per Mk 1, but Can bus, Linbus, data storage. You cant simply talk to the BQ chips, you have to use another BQ chip to talk to the rest. The result is you con only access 15 cell blocks with each PMU, Same as the original OEM use of the LG cell blocks. Thats how they did it. There are some photos of the unit on my EV Support FB pages.

Not sure how I've missed this... Been speaking to some BMW PHEV modules that use these ICs using a Teensy (but anything with UART would do). https://github.com/mjc-506/bmsSerial You talk UART to the first module, then the rest of the modules talk to the first over a daisychain connection (described nicely in the TI datasheets)

I just found this thread (far too late) and just wanted to mention that is is possible to talk directly to a string of 16 bq76PL455A-Q1 modules without modification, and without buying another bq76PL455A-Q1. The daisychain protocol is fully documented in the datasheet, however it does require a little extra external hardware. I use a RPi Pico and RS422 transceiver. I've developed this into a module that can be used either as a standalone balancer, or to communicate with a string of these batteries by CAN bus.

Full details of the project on this thread: viewtopic.php?f=13&t=2123

I know Peter is already aware, but I thought I'd mention it here too. This isn't necessarily a better approach than using an extra bq76PL455A-Q1, but it is easier and safer than modifying a bq76PL455A-Q1 board inside an existing battery.