The information is in the virtual /proc filesystem (unless you've configured your system not to use that). Can't remember the exact files, but there's a batt
under /proc somewhere, in which there are files like 'state' that give you the information. Maybe use
find /proc -name "batt*"
to locate it, and then 'cat' or 'less' or 'more' or 'most' the file to see the current contents.
/proc is a virtual filesystem (so it's not "real" in the sense your /home is), a kind of "peek hole" into the kernel. The files there give information about your system and/or kernel (cpuinfo, meminfo etc.)