This happened to me last Dec.2017, voltmeter reading 12.5 (engine off) and 14.1 (engine running).
Pansin ko hirap na mag-start sa umaga, what i did was the old school way of testing the battery., which is turn-on the headlight, crank the engine.
Eh nag-blink na yung headlight ko, so ayun napabili ako ng battery ng wala sa oras. Sabi ko nalang sulit na rin battery ko which is almost 2.5 years na din.