I would check the battery with a volt meter when I put the boat away and note the voltage, should be 12vdc-13vdc depending on level of charge. Then check it periodically over a few days while stored and everything turned off and see if it drops, shouldn’t drop much at all. If continuously dropping then something is drawing it down. If its steady maybe turn things on one at a time while ready the voltage and look for a significant change in voltage. Something may be shorted enough to kill it but not blow a fuse. Look for evidence of mice chewing. Good luck

 

Sounds like the regulator is allowing the battery to overcharge.

 

yup and over charging kills

 

wouldnt you use a amp meter to check for draw ? I would check starter , radios . voltage regulator . but with a amp. meter you will be able to see the draw. just my 2 cents. good luck

 

Yep both would show power loss. The internet says you want to keep the charging voltage under 13.8vdc for long charges (tending) and 14.4vdc for 8hr or less charges. I would assume the same applies to an alternator charge.

 

I would suspect a faulty regulator, it may be overcharging after it gets warm.. another thing to check is all the ground wires, make sure you are getting a good uninterrupted ground to the battery and to the regulator..

 

I think I would start back at voltage reg many times I have gotten bad ones out of the box or failed shortly after, or starter solenoid, and then the chase begins

 

See if the battery is hot after you get done fishing.

 

Thanks for the advice. I am not great at working on the boat myself.
Took back to XXXXXX Marine where I had regulator installed and had them check it again over extended use and extended sitting. Regulator seems to be working giving constant charge, even after extended running. After sitting for several days the battery isn't loosing any noticeable charge.

How would I check the starter or solenoid? Wouldn't that only effect things when I start the engine?

If anyone recommends someone near the Canton or Akron area, please let me know. My mechanical and electrical skills are limited.

 

Thanks for the advice. I am not great at working on the boat myself.
Took back to XXXXXX Marine where I had regulator installed and had them check it again over extended use and extended sitting. Regulator seems to be working giving constant charge, even after extended running. After sitting for several days the battery isn't loosing any noticeable charge.

How would I check the starter or solenoid? Wouldn't that only effect things when I start the engine?

If anyone recommends someone near the Canton or Akron area, please let me know. My mechanical and electrical skills are limited.

Did XXXXX Marine offer any solutions to why your batteries are getting destroyed?

 

On many boats, the engines (starter ignition) is still connected even with the electric kill switch in off position. This would indicate it is somewhere along that circuit. You should be able to put a meter on the battery and check for a draw. However, if you are running the boat weekly, that little of a draw should not kill the battery. Thus as others said, i think you are getting over charged. I killed a 3x battery bank twice in 13-months, just outside warranty period 2nd time, due to overcharging. In my case it was a faulty onboard charger that simply cooked them - boiled out all fluids... Never popped any fuse or breaker. Batteries were bone dry.

 

I would think once the battery gets a full charge the voltage regulator should drop the amps going to the battery. I would check the amps going to the battery after a long run. I may be totally wrong about this but I know the gauge on my boat the hand drops way back after it runs for awhile.

 

I,ve used vics marine in brimfield about a 30 mile drive from louisville ,have all ways been treated well. and fair on price. I too would run it again and then touch the battery case it should not be hot. reg should adjust voltage as needed. don,t think it should be a constant 14v.

 

Snakecharmer, no they could not figure out why I fried two batteries. It's a place near PLX that I heard has a good rep, I don't want to name them bc they have spent extra time with me trying to figure out issue and I am not sure they have done anything wrong. I have sat right with them while they test everything and troubleshoot. They have been completely stumped. But just like garages for your cars and trucks, I never really know.

Vic's isn't far from me as I work in Louisville and sometime store the boat at the old 84 Lumber in Alliance. I might give them a chance to look at it.

May take boat out in the morning on PLX for a family cruise and see if battery hot after running for a while.

All suggestions have been very appreciated. I am sure many of us have been frustrated boat owners at one time or another. I have just dumped $ and time into trying to get this right and feel like I haven't gotten anywhere.

 

I think it would be an overcharge issue. I had the same battery on an 1982 85 HP merc and it fried my blue top optima in about 3 months. Most of the older Mercs have a rectifier but not really a regulator so they depend on the wet cell batteries to regulate the voltage by boiling off some water. With the sealed AGM batteries they can't regulate the voltage right and overheat. I put a regulator on it from an Evinrude that is a rectifier/regulator and solved the problem.

 

Catfish, this sounds like it could be my issue

 

Maybe install a temporary amp guage just to watch voltage output and see when or if it drops while running.

 

Catfish, I did some research and on another forum a few people posted that older mercs voltage regulators are not compatible with AGM batteries like my bluetops. Can't find it anywhere on Optimas website but several people discussed it in the past few years. I appreciate everyone help. Fantastic forum!
I may be selling the bluetop I just exchanged.

 

https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm
This web page gives information on agm batteries showing that they are sensitive to overcharging. The 91 merc is a simple full wave rectified system without a voltage regulator. It would cook the agm battery on long runs. It depends on lead acid batteries to regulate the current based on demand and can handle the higher voltage output of the regulator.
Higher rpms of the motor produce a higher voltage that is hard on the agm battery.

 

https://www.boatingmag.com/converting-your-outboards-unregulated-charging-system
This is the regulator rectifier that I used. It held the voltage at 14v max and worked fine.