Jump Starter Packs

[TPC]

Thats too low, mate... for a LiFePo 90 to 100% S.O.C. no load voltage should be up in the 13's or even very low 14's.

Did you measure that voltage at the "jump start" terminals or at one of the other pairs?
The "jump" terminals are 'hot' off the battery pack but on a lot of the various packs those 'aux' and 'test' terminals will have circuitry on them and you may not be seeing the battery itself

I would have thought the maximum voltage would be 12.6V out of these.
I believe they are using 3.6V cells that have a maximum voltage of 4.2V and have 3 in series for a maximum of 12.6V fully charged.