[frostschutz]

it's just "{battery}", if you use "[{battery}]" it should literally show as "[42%]" on screen. (without the quotes)

the % char could be problematic, since that is also format string for date so... "{battery}d" could come out as 42%d -> 4206 instead of 42% so - yeah

I'll be fixing that... until then add a space or comma or harmless after {battery}