This is a kernel module I wrote (based mainly on the test_power module included in the Linux kernel source) for simulating multiple batteries on Linux.

This is my first module, so don't hold me responsible if you use it and it causes a kernel panic. =)

This is something I wrote a while ago and am not actively maintaining, so don't be surprised if it doesn't compile against newer kernels or otherwise does not work!

You can build the module with a simple make, and load it with insmod:

$ sudo insmod ./fake_battery.ko

You can write values to /dev/fake_battery to change the current charging/discharging and charge levels of the battery:

$ echo 'charging = 0' | sudo tee /dev/fake_battery # set state to discharging
$ echo 'charging = 1' | sudo tee /dev/fake_battery # set state to charging
$ echo 'capacity0 = 77' | sudo tee /dev/fake_battery # set charge on BAT0 to 77%
$ echo 'capacity1 = 77' | sudo tee /dev/fake_battery # set charge on BAT1 to 77%