@Iholland17 - The optional charger is a CVCC charger and will stop at whatever safety limit they use.
They cannot go over 12.6V so they are normally a few tenths under.
This will affect full charge but not to the extent you are showing.
Do you have a proper li-ion charger?
Or - can you measure the voltage on the charger when it goes from red to green? It should be well over 12V when the charger cuts off and the resting voltage should be well over 12V too. If you don't get 12.x volts, see if there is an imbalance in the cells.
For the purist among us [guilty], know that the upper end of the charge voltage still carries a lot of capacity. I use a more precise charger to ensure my cells are full [and faster charging]. I am using the on-board charge capabilities rather than remove cel