FETguy
New Member
That's good question to begin with. The answer is no, the balance boards are powered by a HV to 24 VDC DC/DC converter in the BMS box, and without that they are unpowered. The balance IC is a Panasonic (now Nuvotron) AN49503A and study of the data sheet for that shows that it is entirely controlled by a host uC via SPI. Without SPI activity, it times out and goes to a low power state, which is why these batteries are in such good SOC after 3 years in storage. If we connect our own 24 VDC to the balance board it may come to life and start balancing; I have not tried that yet so don't know.
There is also an interesting daisy chain scheme by which the balance board in each module powers up the next lower board through a relay; I suspect this is orchestrated by the master board in the BMS box and is how the modules are assigned CAN IDs.
Will start posting my sketches shortly.
There is also an interesting daisy chain scheme by which the balance board in each module powers up the next lower board through a relay; I suspect this is orchestrated by the master board in the BMS box and is how the modules are assigned CAN IDs.
Will start posting my sketches shortly.