Thanks for everyones input. The general consensus seems that it is not a good idea then.
I am trying to find a rechargeable battery that will fit inside the cavity of my rocker box which has 3" of height.
I want to power the following with it:
Mirror cooling fan
Secondary dew heater
Eyepiece dew heater
Finder dew heater
And also perhaps my Argo Navis.
Can anyone suggest any particular battery that would fit in this 3" space??