How to tell if Charging system is working

[fairpilot]

I am curious as to what voltage i should get while underway if I use a tester and touch terminals. I know in a car i will get around 14 volts, not sure the output of the boat charging system though. I seem to have both batteries that wont hold charge or are not being charged by boat. One is only a little over year old and is a deep cycle from wal-mart (prob junk), other is a Duracell about 3 yrs old. I am going to have them load tested at Auto Zone and see if they are just actually shot.

 

[swatski]

I am curious as to what voltage i should get while underway if I use a tester and touch terminals. I know in a car i will get around 14 volts, not sure the output of the boat charging system though. I seem to have both batteries that wont hold charge or are not being charged by boat. One is only a little over year old and is a deep cycle from wal-mart (prob junk), other is a Duracell about 3 yrs old. I am going to have them load tested at Auto Zone and see if they are just actually shot.

Assuming no big extra load (like ballast pumps running), I see about 14.2-14.3V on plane and 13-ish at idle, I think. I believe I have the same charging system with stators.

EDIT: different than with engines off - I see 12.4-12.5V or so.

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