Alternator Performance Question

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PNM

Veteran Member
Joined
Jun 4, 2021
Messages
86
On a recent move to a new marina, I noted that one of my two engine alternators was not working. To keep both start batteries + the house battery charged, I combined the two start batteries using the battery switches - set to both - and the house battery with a jumper cable.

My Port alternator did not kick in until the batteries' charge were just above 12 VDC on the voltage guage. Then, the alternator produced 14 vdc charge to all batteries.

I was pretty happy, except, I wondered why the alternator did not kick in at a higher voltage that just above 12 vdc.

Am I unnecessarily worried. Is this normal performance, or should I replace both alternators?
 
Not sure if seeing voltage only is telling the ALT is not charging. an AMP reading showing current flow may be more telling.
I have been cycling my house bank at the dock overnight, inverting, then charging shows slow increase in volts while amps are 100 for some time before dropping as voltage comes up.
 
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