Is there a formula for figuring out what a full charge would be on any given battery pack, meaning, if its a 4.8 volt pack you would multiply 4.8 x ? = 5.5 or what ever the pack voltage is, you multiply that by this and it gives you full voltage amount?

For Nimh and Nicd, the full voltage charge of a cell is 1.4 to 1.45V. So a 4 cell pack will show between 5.6 and 5.8V fully charged.
Pete

Thanks, that helps

Like pilotpete2 said... it all depends on the chemistry of the battery you are using.
3.7v LiPo cells will be fully charged when it reaches 4.2v/cell
3.3v LiFe cells will be fully charged when it reaches 3.6v/cell