intermittent battery charging problem.

[RobinEllis]

I have an intermittent battery charging problem.


The engine stopped charging the battery.
Went back to dock and plugged in. Still not charging.
Next morning, fully charged.
Went out again, engine charged the battery.
Next day, engine not charging battery.

Any ideas?

When I say not charging I mean: When the engine starts it shows normal charging (about 14A) but drops almost instantly to about 0.7A.

No idea what the problem might be.

[JoeRobertJr]

Hi, Robin,
What is the battery voltage level before charging? When you see the battery is not getting much current, could the battery already be mostly charged such that it does not need much more?

Welcome to the forum!

[stormalong]

Could your battery be fully charged already? Do you have an external or internal voltage regulator on the alternator? Do you have any solar panels?

What is your method of measuring state of charge?

[thomm225]

Sounds like a connection problem.

Redo/reseat your connections starting at the battery.

[RobinEllis]

The batteries are less than a year old and sealed lead acid.

The voltage on the batteries is 12.2V and the battery monitor reads 55% charged.

[RobinEllis]

Originally Posted by stormalong

Could your battery be fully charged already? Do you have an external or internal voltage regulator on the alternator? Do you have any solar panels?

What is your method of measuring state of charge?

No panels (on the list)
Don't know about the regulator I'm afraid. Boat is relatively new to me.

[donradcliffe]

Welcome to boat ownership. You will learn a lot more about your electrical system, hopefully not the hard way. It will help if you tell us the make and the age of the boat.

PS One of the things you will learn is that sealed lead acid batteries are the worst batteries you can buy for a boat.

[RobinEllis]

2000 Moody S31