I have a Mercury 150 Outboard (s/n: 1B986976) on a 22ft Tritoon boat. It used to have a crappy car stereo with 4 speakers and a single AGM battery as the start/run and stereo battery. Everything worked fine. I have now upgraded to a Fusion head unit and marine grade speakers, amp, and sub. I also installed a second battery selection switch and a second AGM (both batteries are identitical 24A-AGM Interstate Batteries purchased within 2 weeks of each other) battery. My challenge is that now it doesn't seem like the engine wants to charge the batteries. When I came back in, the batteries are pretty weak. I fully charged the batteries and then took some measurements.
To make things simple, I disconnected the second battery so it isn't in the equation. For these tests I only have a single Interstate Battery (24A-AGM) hooked up. All measurements were taken with a digital volt meter connected to the batter terminals. At rest, I read 12.8 volt at the battery. I started the engine and at idle, the voltage read 12.4 volts. This is still about what I would expect. With the engine in netural running just over 2k rpm, I get a reading of 14.5 volts (took about 2 minutes to get there, but you can see the voltage steadily climb until reaching 14.5 volts). To me, this looks like everything is working. So, I go on the lake. I kept the radio and lights off (point is, I kept the electronics in the exact same state as when I was running in neutral at the dock). I can not get the voltage to read more than 13.16 volts regardless of RPM. I kept the boat over 2K in gear for over 20 minutes (I did vary a bit from 2k up to 4k to see if it made any difference). If I turn the radio on, it will drop to 13.12 volts (I did expect a drop). Shouldn't it still put out 14.5 volts in gear? Could this be a weak stator or voltage regulator? I don't understand why, all things and draws being equal, why I can get 14.5 in neutral, but can't get above 13.16 in gear. Would explain why the battery is about dead every time I I go out.
I don't know if this is working by design or if I have a problem. My marina says everything is fine, but the low voltage while in gear really surprises me. Any help troubleshooting this would be GREATLY appreciated.
Thanks. Brian
To make things simple, I disconnected the second battery so it isn't in the equation. For these tests I only have a single Interstate Battery (24A-AGM) hooked up. All measurements were taken with a digital volt meter connected to the batter terminals. At rest, I read 12.8 volt at the battery. I started the engine and at idle, the voltage read 12.4 volts. This is still about what I would expect. With the engine in netural running just over 2k rpm, I get a reading of 14.5 volts (took about 2 minutes to get there, but you can see the voltage steadily climb until reaching 14.5 volts). To me, this looks like everything is working. So, I go on the lake. I kept the radio and lights off (point is, I kept the electronics in the exact same state as when I was running in neutral at the dock). I can not get the voltage to read more than 13.16 volts regardless of RPM. I kept the boat over 2K in gear for over 20 minutes (I did vary a bit from 2k up to 4k to see if it made any difference). If I turn the radio on, it will drop to 13.12 volts (I did expect a drop). Shouldn't it still put out 14.5 volts in gear? Could this be a weak stator or voltage regulator? I don't understand why, all things and draws being equal, why I can get 14.5 in neutral, but can't get above 13.16 in gear. Would explain why the battery is about dead every time I I go out.
I don't know if this is working by design or if I have a problem. My marina says everything is fine, but the low voltage while in gear really surprises me. Any help troubleshooting this would be GREATLY appreciated.
Thanks. Brian
