Do I have an alternator problem?

[mmcdonald47]

I have a 2011 R25SC that I took to the dealer to sell in September but have since changed my mind. Had no problems with the boat until coming up the Intracoaastal from the Keys, when my thrusters decided to stop. They did a bottom job and detailed the whole boat, and fixed the thrusters. When they went to get the boat ready to splash, they said the batteries were bad and replaced them. Then it still wouldn't start, so they replaced the starter. It was splashed two weeks ago and I headed north and realized my battery was only showing 11.6. I thought since it was on the hard it was not full charged but after an hour it hadn't gone any higher. Thirty miles away my low battery alarm came on and I put it in parallel in order to get to my marina.

Once there i pulled everything off the starter battery and charged it. It showed 12.62 after two hours on the charger. I started the engines and the gauge showed 11.6 and after a few minutes it started descending to 10.8. Someone stated that this was a bad alternator. I was wondering if there was something that was not connected or not connected correctly that could be causing this problem. I have NO batteries now. and my inverter/charger is not working. Anyone have any thoughts?

Walk-In-The-Water
Mike McDonald

 

[Kenny Marrs]

Hello Mike,

Are all three battery banks showing the same low voltage?

The Inverter/charger is a completely separate charging system from the alternator. So that's interesting that neither system is charging the batteries. I would contact the company who replaced the batteries and ask them if they checked to make sure all of the batteries where being charged after they replaced them, from both the engine and battery charger.

Thanks,
-Kenny

 

[knotflying]

Two hours of charging would have only given a surface charge. Also keep in mind that if your engine battery voltage is too low the relays will lock it out from charging. However the alternator should be putting out enough charge once the engine is started and you should be reading about 14.1V. What does your voltage show using the Garmin? Check the wire coming from the alternator has clean connections all the way back to the engine battery. Also check your ground wire from the engine battery all the way back to and including the engine block. Make sure all connections are clean. If all that checks out. Put a voltmeter from the lug on the back of the alternator to the engine block and make sure you are getting a voltage reading. If that does not check out you could have a bad regulator or alternator.

 

[mmcdonald47]

Kenny,

When I got to my marina, I turned off the parallel switch and then charged my starting battery after removing all wires from the terminal. I had house battery of around 14.2, but as the week wore on my house batteries died. Noticed it when my fridge stopped cooling. This boat has been lived in the last four years and I have been in many marinas on shore power. On my DC panel, I leave my fridge on and water pressure on. On the AC panel I always have my battery charger on. Never once has anything quit on me.

I probably could charge my house batteries on a charger, but if my inverter/charger is not working, how would i keep them up. Would low voltage cause the charger not to work? I don't want to assume it is the alternator and I do not want to spend money chasing down a problem. would Knotflying's suggestion help pinpoint the problem. Like I said I have shore power and everything is working other than the DC panel. Which leads me to another question, I have a NovaKool fridge, does this not run on both Dc and Ac current?

Walk-In-The-Water
Mike McDonald

 

[tugnnaweigh]

IMHO Kenny is on the money here, have the company that installed the new ones check the two charging systems which often is the final step when replacing batteries. It can also be the first step when dealing with battery problems, i.e. ensuring it's not a charging problem. One tip here is your charger may need to be reconfigured to the new batteries if you went from flooded plate to Absorbed Gas Mat (AGM) batteries. On the ProMairner 20 amp charger a plastic screw on the side would be changed from a black one to a gray one. I had to do this on my ProMairner 20 when I went to AGM batteries and the ProMairner folks sent me one at no charge.

Another tip is when struggling with any twelve volt system; what your looking for is bad grounds. What somebody said, start with the ground at the engine and trace backwards to the batteries, cleaning grounds as you go. Even is this does not cure it, it will not hurt anything and probably improve things, scratching a few items off the "I oughta do this every few years regardless" list.

Take heart, you've done the one thing many many can't bring themselves to do; you've replaced batteries! Some folks limp old batteries along for years ruining voyage after voyage, don't ask me how I know this!