SpudFiles

I have a 7.2 volt 1100mah battery pack for my rc car. I am looking to add one more cell to make it 8.4 volts which is the max voltage for my car. My question is does the cell I add have to be 1100mah or can it be different? I do plan on charging them as one pack. My second question is are all sub c batteries the same dimension no matter the mah? Thanks in advance.

it does not have to be 1100mah, but if it is less, that will make the entire pack run out of juice faster.

I would make it a point to match the cells if you can.

You would more than likely be better served if you just purchased a commercial 8.4v cell with improved amperage capacity.

If the added cell is less then 1100 mAh it may be over-drained and you dont want that.
If the added cell is more then 1100, then that cell may over-drain the rest if the pack, but it probably will not have enough power to do serious damage.
It would be best if the added cell is 1100 mAh and it is the same brand / type.

My mistake I need 2/3a size batteries. I think I may just buy a bunch of these and make a couple of battery packs. I am pretty limited to size on my truck due to lack of room.