So i have 3 chargers 1 of them is busted.. I would like to make a circuit that will charge the lithium ion battery pack's for the radios. They are 7.4v Li-ion 1800mAh to 3800mAh but more like 2600 i would guess you know "China". they have a simple the circuit in the charging base i guessing there just dropping the voltage from 10V to 8.4v From pics on the internet of the battery's that are open it looks like they have a circuit board in with the battery's for Controlling the charge? Can i just put a Simple voltage reg in there to drop 10 or 12V down to 8.4v? and is there away to add a done charging LED?