Battery not recharging

[WyoChris]

I think I have an issue with the alternator of my boat engine. My boat is a 97 Lund Mr Pike with a 115 HP Yamaha four stroke. The engine battery ran out of juice a few weeks ago and then it did it again a few days ago. Unfortunantly, the engine will stop, even after being started, if the battery goes dead.

I took the battery to the auto parts store, they ran some tests, and said the battery was fine it just lost it's charge.

Anyone ever had this problem? Is there a way to test if the alternator in the engine is shot? Also, what is the best way to fix this? Will I have to visit the boat shop?

Any help would be greatly appreciated

[broken_line]

i have remidy is just to throw it on the charger while you sleep...

[marine_man]

Do you have a multimeter?

Measure the battery voltage with the motor off. Then, start the motor (in the lake or on the hose) and run the throttle up past 1/2. Does the voltage increase by at least 1 volt, if not more?

If so, it's not a charging problem, you have something drawing your battery down while you're not using it.

If it does not rise, you've got charging problems... do this test first and we'll see where we go from there.

marine_man

[ANYFISH2]

Marine man is right. Any shop will probably check it for you for free as it only take a minute.

I had the same problem on opener with ironically the same motor. It turned out it was just the batteries. Thank goodness because the charging system components are outragously priced.

[WyoChris]

well just got it back from the auto store... the battery is good. Looks like it's the alternator or a wiring problem. I guess i'll be bringing it to a yamaha dealer next week.

Fortunantly, I have a full charged battery for the weekend! If it dies again, i'll have a trolling motor battery to get me back to the boat launch

[gofishingtom]

what graph u running on your boat? if it is a lowrance with gps the antenna if connected will draw power even when the main switch is off..My 27 if i dont unplug the antenna everytime it draws down my battery enough after 2 or 3 days that i cant get motor started

[marine_man]

Did you do the check I described above?

marine_man

[WyoChris]

Marine man.... thanks for your help.

Unfortunantly, I do not have a multimeter and can't check this. How cheap are these to buy?

The wierd thing is...... I was on a 10 minute run down the river and the battery actually died while the main engine was on and was crusing at 40 MPH, so im guessing the motor wasn't recharging it.

However, this is my first boat with a motor over 18 HP so let me know if i'm missing anything.

Thanks

[marine_man]

Does your depth finder have a voltage output on it? It would be in one of the data displays (not the plotter or the depth finder view, but the one that shows most of the data). That would accomplish the same things.

You can get a cheap multimeter for $10.

I was on a 10 minute run down the river and the battery actually died while the main engine was on and was crusing at 40 MPH, so im guessing the motor wasn't recharging it.

That doesn't necessarily mean it's the motor. The battery could have been weak before you started, or right on the verge of not being enough to keep the engine running.

marine_man