I am getting to grips with my new OBDeleven dongle and wondered how accurate the battery voltage indicator is. With the car cold and not running it shows the voltage as 11.9v when cranking this drops to 9v and when running its 14.4v after running for about 10 mins the non running voltage goes up to 12.4v but is immediately draining. The other question I guess is the battery on its way out, car is 5 years old next week. 

Might be worth asking the OBDeleven creators?

 

Just to point out, even if OBDeleven is completely accurate, the voltage at the OBD port is unlikely to be identical to the battery voltage so it may show a slightly lower reading

 

A proper battery tester is a better plan to asses the battery health as there is more to it than just resting/running voltages