Did you have a load on it when you measured ? Remember that cheap power supplies put out "something vaguely like 12 volts if you draw exactly the right amount of current" while good power supplies put out pretty much exactly 12 volts.

12 volt car / motorcycle batteries, on the other hand, put out 13.8 volts +/- a volt or so depending on whether or not you are charging.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8