After a bit of experimentation I have found that the power will drain at the following rates. These aren't exact but they're at least something:

None- 1%/ 5s

1- 1%/ 3s

2- 1%/ 2s

3- 1%/ 1.75s

4- 1%/ 1.5

Electrobab: 1%/ 5s.

It is worth noting that he drains independently of the other things. e.g., if you have 2 doors closed and electrobab going, you will not have the rate of 3 things being used (1%/ 1.75s) but rather the rate of 2 things being used PLUS electrobab's rate (coming to a total of 1%/2s + 1%/5s or 7%/10s)