Battery Died

[joshstan1978]

My 1989 Rinker with a 4.3 Mercuiser would not start yesterday. I keep a small battery jump pack on the boat and it started using that. I was on the lake for about 4-5 hours, a mix of fishing and cruising. We did some WOT trying to sort out some backfire issues (tune up probably). Ran the radio a little, used the trim lots, and ran the blower motor each time before starting and moving. This is my first inboard so I am not sure how long to run the blower motor. My question is should the alternator keep the battery charged during operating like this? Do I start by checking the battery or alternator? When I run the trickle charger on the bad it shows it’s good.

Thank you in advance. This forum has helped me and my family enjoy so much time on the water.

 

[alldodge]

Your Bat should have no problems staying up using the boat in that manor.

Your Bat should read 12.6V or above just sitting for a couple hours off a charger. If it reads lower there would be a problem.

When motor is running the Alternator output should be around 14.5V

 

[airshot]

Why only one battery ?? Many opt for dual batteries in bigger boats, even my 16' alum has two batteries the engine has acess to. Have your battery tested, free most places...check alternator output, the make corrections on your findings.

 

[joshstan1978]

Your Bat should have no problems staying up using the boat in that manor.

Your Bat should read 12.6V or above just sitting for a couple hours off a charger. If it reads lower there would be a problem.

When motor is running the Alternator output should be around 14.5V

View attachment 382454

I checked and the battery was around 12.5. It stayed around that with the engine running and a little increase in rpm didn’t do anything. I was in the yard on muffs so no high rpm’s. I tired a different battery tested higher sitting and still around the same running.

 

[joshstan1978]

Why only one battery ?? Many opt for dual batteries in bigger boats, even my 16' alum has two batteries the engine has acess to. Have your battery tested, free most places...check alternator output, the make corrections on your findings.

 

[joshstan1978]

I haven’t had the boat too long so I haven’t installed a second battery. I will be checking the alternator when I pick up a better method of reading it. I don’t do much with electrical so learning lots about it. The gauge on the boat is barely around 12 so guessing alternator.

 

[Grub54891]

The parts store can load test your alternator and battery if you bring them in. If either is bad they will tell you. Always replace those parts with Marine rated parts.

 

[joshstan1978]

The parts store can load test your alternator and battery if you bring them in. If either is bad they will tell you. Always replace those parts with Marine rated parts.

I agree. I don’t want to go BOOM

 

[mike_i]

Don't go by what the boat battery gauge says. Use a digital voltmeter. Get the battery load tested.

I haven’t had the boat too long so I haven’t installed a second battery. I will be checking the alternator when I pick up a better method of reading it. I don’t do much with electrical so learning lots about it. The gauge on the boat is barely around 12 so guessing alternator.

 

[joshstan1978]

Don't go by what the boat battery gauge says. Use a digital voltmeter. Get the battery load tested.

The battery was 12.7

 

[airshot]

I checked and the battery was around 12.5. It stayed around that with the engine running and a little increase in rpm didn’t do anything. I was in the yard on muffs so no high rpm’s. I tired a different battery tested higher sitting and still around the same running.

This is a clue that the charging system is not working properly...