ALTERNATOR

[goodoldboat]

Im having issues with charging , was charging fine yesterday but today
with the engine running its not putting anything back ..

The belt seemed loose so I tightened it , but no charge going back to the batts as far as the voltage gauge tells me .


any thoughts ?

[sdemore]

Is there any difference in voltage when the engine is running vs off? You may need to use a voltmeter instead of the engine gauge, just to get a more precise reading (and rule out the gauge being the problem). I would check it at both the alternator and the battery. Those readings should be the same, but could also tell you if it is the battery cable or corrosion on the connections at the same time.

Steve

[goodoldboat]

thanks when I am testing the batteries , they are in parallel I test across from the black on one to the red the other ?

[canadiankris]

Hi Steve,

separate batteries when testing,

doing a load charge when they are hooked up to equipment can be bad for some of the equipment (if it is turned on) the low voltage will cause strain.

voltage testing batteries in parallel will tell you the average of the bank, not the actual voltage of each battery in that bank.

best to wait 15 minutes (about) after disconnecting charging sources before testing.

A laser thermal gun will help identify batteries that are running hot, they are the weaker ones in the bank.

Kris

[Easy Rider]

Is it possible that the batteries are fully charged already?

Chuck

[Al Schober]

You'll need a handheld voltmeter to tell you whether the alternator is putting out the volts you need to charge. If it's not making volts, you've got a problem with the alternator itself or its regulator (may be internal or external). Check voltage between the alternator case and the big lug on the back (should have a fat orange wire).
If the alternator is making volts that aren't getting to the battery, you've got a wiring issue. Could be in the positive lead from the alternator to the battery or in the return leg from battery - to the alternator case. The bolt between the engine bracket and the alternator case is a known bad actor. I ran a separate ground lead from the alternator case to the engine block.

[goodoldboat]

so it could be the bad actor bolt that is not making a grounded circuit , you are not talking about the adjustment bolt arm .

[sastanley]

GOB, yes...any bad connection in the circuit all the way around the loop, including ground. It is DC, direct current, the ground side has to be as corrosion free as the positive side. Our alts ground on the swing bracket, not necessarily the adjustment arm, and usually there is a ground strap on the flywheel cover somewhere.. The entire block is basically a ground.

[goodoldboat]

and the issue was ....


Not Enough throttle ..........apparently at a low idle my alternator will not put out more than 12.50 or so .

once I throttle up it goes to 13.95 and 14.35 .. at cruising speed .


this is a new boat for me , I learn something new every time i'm aboard .

thanks to all who responded