mattkab
Senior Member
All:
This past Saturday we took our boat out for a few hours on a short evening cruise with friends. About 3/4ths of the way through the trip, I noticed that my battery light on the gauge panel was lightly lit. I confirmed low battery on the breaker panel with the analog gauge showing ~12.5v. Usually it's up near 14v with the alternator output.
We had been cruising at just above idle (~900RPM) for a couple hours, dragging a salmon lure at 2 kts. We pulled up all the gear, turned off all the extraneous 12v loads (namely refrigerator and radar), brought the RPMs up to 1600 and got home without further incident about 20 minutes later. I thought, though, with that amount of runtime the battery bank would be charged above alarm stage, but it wasn't.
We tied into shore power, and I noted that both banks were taking a charge before we went home. Sunday we went back down to the boat to take a look at things. Charge indicators were showing float stage on both banks. Disconnected shorepower, and turned the engine over (just fine, no problems). But even after an overnight charge, the alarm light was still lit. Analog gauge still showing high 12v readings.
I shut down, and went into the engine room. I grabbed a hydrometer to first test the batteries -- every one of my house batteries were bone dry! I couldn't even get enough water to do a test. Starting battery was good to excellent on all 6 cells, so that's good at least.
So my assumption is that the house bank is toast. Also, I'm concerned about the alternator, but not for any evidence. I did not meter the output while down there yesterday, but will do so soon. So my current plan is to first replace the house bank batteries with 6 new group 24s. Then, meter the output of the alternator, and if that is funky at all, look into replacing that as well.
Does that sound reasonable? Any other diagnostic checks, or items I should look at?
Any other money-saving advice?
I really don't like when people ask for help and then don't give enough information to have people around the world help diagnose, so here's a bullet list of the essentials:
This past Saturday we took our boat out for a few hours on a short evening cruise with friends. About 3/4ths of the way through the trip, I noticed that my battery light on the gauge panel was lightly lit. I confirmed low battery on the breaker panel with the analog gauge showing ~12.5v. Usually it's up near 14v with the alternator output.
We had been cruising at just above idle (~900RPM) for a couple hours, dragging a salmon lure at 2 kts. We pulled up all the gear, turned off all the extraneous 12v loads (namely refrigerator and radar), brought the RPMs up to 1600 and got home without further incident about 20 minutes later. I thought, though, with that amount of runtime the battery bank would be charged above alarm stage, but it wasn't.
We tied into shore power, and I noted that both banks were taking a charge before we went home. Sunday we went back down to the boat to take a look at things. Charge indicators were showing float stage on both banks. Disconnected shorepower, and turned the engine over (just fine, no problems). But even after an overnight charge, the alarm light was still lit. Analog gauge still showing high 12v readings.
I shut down, and went into the engine room. I grabbed a hydrometer to first test the batteries -- every one of my house batteries were bone dry! I couldn't even get enough water to do a test. Starting battery was good to excellent on all 6 cells, so that's good at least.
So my assumption is that the house bank is toast. Also, I'm concerned about the alternator, but not for any evidence. I did not meter the output while down there yesterday, but will do so soon. So my current plan is to first replace the house bank batteries with 6 new group 24s. Then, meter the output of the alternator, and if that is funky at all, look into replacing that as well.
Does that sound reasonable? Any other diagnostic checks, or items I should look at?
Any other money-saving advice?
I really don't like when people ask for help and then don't give enough information to have people around the world help diagnose, so here's a bullet list of the essentials:
- House bank: 6 group 24s, approximately 5 years old (no stickers marked, going off notes of PO)
- Starter bank: Single group 31, approximately 5 years old
- Charger: 20amp Zantrex True Charge
- West Marine Battery Charge Monitor
- Battery Isolator: installed (not 100% sure on wiring or manufacturer)
- Boat was hauled out in March for new bottom paint and basic engine service - no issues discovered
- Last couple trips the bow thruster has not worked for more than a couple seconds (shuts off). I assumed there was something fouling it and was going to dive it to check, but....