What do you want to know about the battery? Can't it be done by reading files from /proc/acpi/battery?
Personally, I'm having 2 battery's for my laptop: a new/good one and a battery that I broke by having the laptop hooked up to the adapter almost 24/7. When I'm visiting a customer, I remove the old battery and hook up the new one. But sometimes, when I get back to my office, I forget to put back the old battery.
So what I did: I wrote a cron script that reads the serial number from /proc/acpi/battery/C1F4/info to see what battery is connected. And if it's the wrong one, a passive popup (kdialog) is shown.