Bad Alternator? Need your help with dead batteries.

[jwharan]

This weekend, after hitting a shallow spot, i had to quickly shut off the boat to avoid taking in dirt. I also left my automatic bilge pump running all day. The lights went dim, and the starter would not turn over. Just had the clicking sound that you get with a dead battery like in a car. Battery was shot. Charged the battery, boat started right up, after a ride of about 15 min at WOT, i came to and idle, went to raise the trim, and the boat stalled out, again dead battery. Replaced battery which was couple months old, with new battery. Engine turned over enough to barely start once, then immediately, that battery was dead as well. What did i do to my boat, and why is the boat now draining a brand new battery almost immediately? Do i just need a new alternator, or did i do more damage than I know, when hitting sandy bottom. Please help. Thanks!<br /><br />The boat is a 18" I/O Mercruiser 4.3L 1997 Thanks

 

[Don S]

Re: Bad Alternator? Need your help with dead batteries.

Sounds like loose battery cables (Loose the wingnuts).<br />Get some real nuts to hold the battery cables tight, and make sure the cable ends aren't all corroded and loose on the battery cable. Also check both ends of the cable.<br />Could also be a bad alternator (Just a case of bad timing) cause almost running aground doesn't destroy alternators. check the belts also. Loose belts don't charge batteries either.<br />Did you look at the voltmeter while running? Did it show it was charging? You could also start the engine, and while in neutral check the voltage at the battery with the engine running around 1500 rpm. Should show a little over 14Volts.

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

Where do I use the voltmeter? I can check the battery, how do I verify that it is charging? Do i need to check the connection to the alternator? Any idea where I locate the alternator on this engine? Haven't really looked at it yet. What would cause the new battery to drain immediately?

 

[Dunaruna]

Re: Bad Alternator? Need your help with dead batteries.

Originally posted by jwharan:<br /> Where do I use the voltmeter? I can check the battery, how do I verify that it is charging? Do i need to check the connection to the alternator? Any idea where I locate the alternator on this engine? Haven't really looked at it yet. What would cause the new battery to drain immediately?

Use the volt meter at the battery. The voltage test will verify whether or not it is charging. Yes, check the connections to the alternator. The alternator is the thing that has a belt wrapped around it at the front of the motor. You cannot drain a fully charged battery 'immediately', physically impossible without getting third degree burns. It is either - not charged up or the connections are bad.<br /><br />I suggest that you take your boat to a mechanic or auto electrician.<br /><br />Aldo

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

Any other ideas, what is killin my battery?

 

[randyo]

Re: Bad Alternator? Need your help with dead batteries.

If your battery seems dead to you, can you drop it off at an autoshop for 30 mins to have them test it? They can tell you whether it will hold a charge and the condition it is in for free...

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

I know the state of the battery, the issue is the boat is not charging the battery.

 

[cosander]

Re: Bad Alternator? Need your help with dead batteries.

you need to see if the alt has any output.<br />If your alt is spinning with good clean connections and a good battery is going dead then it is time to buy a new alt

 

[Bondo]

Re: Bad Alternator? Need your help with dead batteries.

I suggest that you take your boat to a mechanic or auto electrician.

It Appears that you've Haven't used Any of the Diagnosistic Tips,+ Tests posted for you on this thread,...................<br /><br />I can't see where you've replied with Any Test Values from these tests that Need to be Done,.......<br />

I know the state of the battery, the issue is the boat is not charging the battery. <br />

Please,............ Tell Us How You Know This to be Fact,.....????<br /><br />Without Feedback,+ Actions by You,.............<br />These forums Aren't going to Fix Your Boat,.........<br />You'd Better take Dunaruna's Advice,...........<br />It's the Only Way your boat will Ever Run Again................

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

I'd love to, i'm traveling for work till Fri, I know because I took the expensive route, and bought a new battery, and had the same result. I will test the connections on Friday and Post. Thanks

 

[Bt Doctur]

Re: Bad Alternator? Need your help with dead batteries.

for what its worth<br />Turn key to on,<br />look at volt gauge<br />start motor<br />if reading is above the start reading, its charging,whether its an actual gauge or a 4 line gauge

 

[waterone1@aol.com]

Re: Bad Alternator? Need your help with dead batteries.

You could have a bad alternator, then again you could spend $$$ to find out it isn't the alternator. Thankfully, this should be a fairly simple set-up(as opposed to multiple batteries and isolators). You will need a volt-meter, patience and the ability to follow directions to solve this problem. Start with the above posts on determining if the cables and connections are in good shape. follow up by doing the test as described above to make sure that you are not getting charging voltage to the battery, DVM (digital volt meter) accross battery terminals with key off(should be about 12.5V) next, start engine(in water or with muffs on drive for water), run rpm's up to 1200-1500, put meter back on battery, do you see 13.5-14.5 volts ? if so it is charging, if you still see 12.5 or lower it is not. Assuming it is not charging, do the following: locate the back of the alternator, find the thick wire, most likely orange, with the engine running, put your meter pos. on this and the neg. on ground. Do you see 13.5 or higher volts here? If yes, post that, we'll talk you through the next step. If no,AND you are getting 12V or close to battery voltage? then look at the back of the alternator, besides a black wire, are there any other connections or wires ? If no, the alternator is most likely bad and needs to be tested at a rebuild shop and repaired or replaced. If the answer is yes ( more wires on the back of the alternator- a three wire set-up) please post that, and we'll tell you some more voltage tests to do to determine if the wiring is bad or if the alternator is bad. Remember, if you do any of the above, you will be working on a running engine, take safety precautions. If you are not sure, or feel uneasy about any of this...take the boat to a pro.

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

I will perform these tests on Friday, and post! Thanks all for your help. I have the service guide, which details multiple tests to perform. I will record my results and let you all know. THanks

 

[paulrfrancisco]

Re: Bad Alternator? Need your help with dead batteries.

How about starting the boat, then removing the Pos. Battery connection. If motor stalls, then Alternator is dead... If continues to run, then good... I dont know if this holds true with boats, and newer equipment, but it was an old school way to tell if the car was charging...

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

Lets say hypothetically, that I look at it on Friday and it needs a new alternator? Where can i pick this up? Or do i need to order one?

 

[tommays]

Re: Bad Alternator? Need your help with dead batteries.

that is a new school way of damageing and alt<br /><br /><br />tommays

 

[Bondo]

Re: Bad Alternator? Need your help with dead batteries.

Originally posted by jwharan:<br /> Lets say hypothetically, that I look at it on Friday and it needs a new alternator? Where can i pick this up? Or do i need to order one?

The Part # for a New replacement Alt. for Your engine is 18-5967,....At the local NAPA store,.. wherever your boat is.........<br /><br />If they don't have it "On the Shelf",... It shouldn't be more than a Day away..............

 

[blstanly]

Re: Bad Alternator? Need your help with dead batteries.

Also, keep in mind that if the alternator diodes have failed, the bbttery will be trying to run the alternator as a motor when the ignition switch is on. This would drain your batteries in a hurry. The diodes allow current to flow only one way-hopefully from the alternator to the battery, not the other way around.

 

[jwharan]

Re: Bad Alternator? Need your help with dead batteries.

Good to know, are these diodes repairable or do I need to replace the entire alternator? Is there a way to test the diodes?