Low Voltage Alarm to Optimax

[Mr.Wonderful]

Serial # 2B122759
150 Pro XS

First trip of the season was last Friday to make sure everything was in order and we ran great. On Sunday, during a tournament around 10:00 am I received a low voltage alarm that coincided with my vessel view mobile notification. I’m running a Pro-Guide Group 31 AGM. We idled in and after fishing I took the battery to get tested. It returned 148 CCA. So Pro-Guide sends a warranty replacement that was installed last night. Today at 2:30, I get the same low voltage alarm. No livewells running today. Three Lowrance Live 9’s w/ AT but I was conscious about keeping graphs on standby when not in use.

Does anyone have any ideas or suggestions as to what i could be dealing with?

Thanks in advance.

[EuropeanAM]

Check the battery voltage with the engine running at idle. It's very likely that it's not charging.

Next step is to check the voltage at the large RED output terminal on the alternator with engine idling. Voltage HIGH (higher than 14.7VDC) = Fusible Link Lead blown by reverse polarity connection at battery.