I've switched my notebook to NetBSD, and when I found out that
the XFCE battery plugin had no support for NetBSD, I decided to
add support myself.
The attached patch makes it work with APM on NetBSD.
In fact things work very similar to OpenBSD, so the patch
is quite small.
The only problem that I've found so far is that the panel
crashes if I tick "Display power" in the configuration dialogue.
I don't really understand why that tickbox exists if the plugin
is running in APM mode, since the code that runs when the display_power
flag is set seems to be interested only in things like fan speed
and temperature. Which I always thought were ACPI-only features.
Somebody else with more knowledge of the code should take a look
at this. I don't know if the same crash occurs on OpenBSD, too...