Ibook/powerbook TI bq20851 BMS unseal password

[AC910]

I didn't see this posted anywhere else online, so I'm adding this for anyone that may need it in the future.

The unseal password for a bunch of ibook/powerbook laptop batteries is 0x2083 0x7a43

This password should cover at least these models, possibly more:
iBook (Dual USB),
iBook (Late 2001),
iBook (Opaque 16 VRAM),
iBook (32 VRAM),
iBook G4 (12-inch),
PowerBook G4 (12-inch),
PowerBook G4 (12-inch DVI),
PowerBook G4 (15-inch FW 800),
PowerBook G4 (17-inch),
PowerBook G4 (17-inch 1.33GHz)

This password is needed to unlock manufacturer access in the TI bq20851 bms chip. There's some useful stuff there but also stuff that can brick the battery or cause a fire. If you have to ask what this does or how to use it, you probably don't need it.

Password was pulled from the disassembly of the Battery Update 1.1 updater.

 

[ervus]

Thank you for posting this! I'm guessing this could be used to reset the capacity on rebuilt batteries? I have one battery with new cells that won't charge, and I suspect the BMS needs to be reset.

How are you communicating with the BMS?

 

[Certificate of Excellence]

Thank you!

 

[AC910]

Thank you for posting this! I'm guessing this could be used to reset the capacity on rebuilt batteries? I have one battery with new cells that won't charge, and I suspect the BMS needs to be reset.

How are you communicating with the BMS?

It's possible. I'm still sorting it out myself. But I know modern BMS chips have efuses and multiple levels of authorization. It's hard to say for sure, since a lot of the info is proprietary and not shown on public datasheets. I believe the chip I'm working with is a lot older and simpler and so doesn't have a permanent brick fuse and unsealing should give full access. YMMV.

The BMS uses smbus which is a subset of I2C. Any i2c capable device can access this, such as microcontrollers, raspberry pi, countless usb dongles, etc. I personally use a hybrabus, but I do a lot of embedded work.

You can easily access the bus with the battery connection port.