Battery voltage jumps

I experienced the same issue.
To diagnose this, I wrote a small tool which interact with sysfw through spidev.
And confirmed that, as mentioned in this thread, responses from sysfw are sometimes get corrupted.
I’m trying to prevent this by adjusting intervals between spi_read/spi_write, but if it does not work, we need to implement some kind of error recovery logic in the lpc driver.