bnf doesn't rely on APM in any way - you can safely uninstall it. Although it's nice piece of code, I must admit, that I've also uninstalled APM few months ago - bnf suits my need for detailed info, and standard battery indicator is OK for a "glance" battery status. In my case, it was rather about saving memory, instead of CPU cycles.

As for shutting down - just stop bme, while attempting to calibrate. Then, after EDV=1 and VDQ=0, remember to charge device for a while (via charge.sh script, as per my instructions), before turning bme again - or, it will shutdown device due to voltage lower than it's threshold.

/Estel