Low idle = lights to shut off???

[kenmclaughlin]

Hello everyone,

Earlier in the fall I had some questions regarding my accessories which I have been able to fix! It was awesome to be able to have the boat out at night!! Buttttttt........ the other day I was running the boat on idle for about two hours and all of a sudden the lights just shut off. The other accessories continued to work. I only have one battery and am wondering if the lights would shut off due to running at a low idle and possibly the alternator not charging the battery sufficiently? I could be completely incorrect with this, but before I begin to track the problem, I wanted to throw my question out to everyone. I have a 2006 Harris Flotebote 240 Classic.

Thanks!
Ken

[curtiscapk]

What motor do you have? DID YOU LOOK FOR A LOOSE GROUND?

[kenmclaughlin]

It is a Mercury 60HP outboard. I did a quick search but did not find any loose or separated wires. I wanted to rule out my original thought about the battery not producing enough amperage to power the lights before further tracing the problem.

[Steiner]

Are the lights LED or incandescent?
LED's will shut off at a certain voltage, incandescent should just dim at low voltage.

A stator will put out a good bit less current at idle than when on the throttle. Depending on what all you had running at one time and the state of the charging system, it's possible the battery got pulled down enough for the lights to drop out (If LED).

Try charging the battery up and checking battery voltage with engine off and engine running, and at 2000 RPM or so.

[Marc K]

A simple volt meter will give you the answer. A basic marine battery will show 12.7v to 12.8v when sitting at rest. The battery is being charged when it sees 13.5v to 14.5v.

[kenmclaughlin]

Thanks guys. I plan to pull the battery today, put it on a trickle charger until Friday, and reinstall it. Hopefully, that will fix my problem.

Thanks again!

[Marc K]

Thanks guys. I plan to pull the battery today, put it on a trickle charger until Friday, and reinstall it. Hopefully, that will fix my problem.

Thanks again!

Be aware of the numbers. Example, if your battery is rated 100 amp hours and your trickle charger puts out 1 amp, you will need around 102 to 104 hours to charge it. Some batteries should be charged slower and others stay healthier at a very high charge rate. It all depends on the type and construction.

The single most valuable piece of information is what voltage is being fed to your battery when the engine is running at idle and higher.

Marc

[riplipper]

Did you check the fuse?
There should be one for your lights?
It could be blown or corroded.

[Rick McC.]

Both my try-toon and my airboat alternators put out 14 volts continuously; including at idle.

I had a 2016 60 HP Merc Command Thrust on an earlier ‘toon, and it put out 14 volts as well.