from 'battery-status' page:
"Note: Because battery-status relies on DBus signaling, running it has the unfortunate side effect of activating the battery applet. I will try to find a workaround for this."

my tool bangs on raw metal (/dev/retu) and gives battery voltage as one of digits so you can finetune it for yourself. every % number is only an estimation, be it nokia's applet or battery-status.
and for compatibility you need only /dev/retu (it's not hildon app, it's meant to be run in scripts)