Motor trouble question

[Fisherjoe]

Friend suspects a bad alternator in an '04 60 hp Merc four-stroke. If he starts the motor and then unhooks a cable at the battery, should the alternator keep the motor running?

The battery was tested by an auto mechanic and tested as good. After a short time of running, the motor will die and the battery will not turn it over. He switched to a TM battery and motor would run for a while and die. Battery would not turn motor over. All batteries were tested as good.

Any other ideas? Thanks.

Joe

[Bassin]

On most boat engine, they don't recomemd runing the engine with the battery cable disconnected, this will burn the rectifier or alternator up in a hurry. A cheap volt meter will tell you if the charging system is working.

[hardestyeric]

Bassin is right. Get the motor started, leave the cables connected to the battery and put the volt meter on the battery. You should have over 12 volt at the battery.
I wouldn't recommend "tinkering" with an 04 motor and it's electrical system unless you are highly trained. If you can't figure it out fairly quickly I would take it in to the shop.
Eric H.

[Moose1am]

Should your battery read over 12 volts on the volt meter with the engine running and the battery cables connected with that keep your starting battery fully charged up if you use the gas motor for just a few minutes and then have to start the motor again.

Say you are moving slowly on bluegrass pit from one spot to the next and then you turn the motor off when you get there. The trip there may have only taken five minutes or slightly longer. You get there and turn the motor off and fish using the trolling motor and then start the main motor up again and move to the next spot and do this over again.

The reason I ask this question is that I do this a lot and find that my starting battery needs a little charging form time to time when I am at home. I get the battery charger (Minn-Kota) and hook it up to my starting battery and it will take some charging for about 30 minutes and then the charger shows the battery fully charge.

I'll get my volt meter out the next time I am running my boat motor and check the voltage.

I am finding the same thing with my truck.

I keep the terminals clean and tight on the connections.

Once I blew out a rectifier as a few of the one way diodes were blown out. I was thinking that I had to disconnect the battery from the boat before I put the portable charger on the battery. I got the idea that I had blown the diodes by trying to charge the starting battery with it still hooked up to the motor..... But I don't remember where I got that idea. It's probably my overactive imagination and being too cautious that gave me that idea? Anyway I'll check the voltage and maybe even add a volt meter to my boat to help me check it each time I run my engine. That should not be too hard to do.

My truck has a volt meter in the control package that came with the truck and it shows that it's charging over 12 volts on that meter. But the meter is not marked at each volt reading. It's only marked at 12 volt and then at 18 volts so I have to guesstimate the actual volts while looking at the meter.

So I got one of those digital volt meter things that plugs into my cigarette lighter and that reads the volts on the display. I found that while driving it's showing 13 to 14.6 volts being generated.

But my truck battery seems to be running down as when I start the truck the little red battery light comes on for a few seconds and then goes out. Those are idiot lights in the trucks dash panel.

Once this last week I left the truck's headlights on for a couple of hours and the truck would not start at all. The Every-ready from Walmart Truck Starting battery is about 2 or 3 years old now. It charged back up in a few hours using my Minn-Kota portable Battery Charger and I was good to go again.

I took the truck to auto zone and they tested my battery and the alternator and they both tested OK. But that **** idiot light still comes on from time to time for a while.

I know the light comes on when first starting the truck but it should not stay on long. Sometimes it stays on for 30 seconds which makes me think that the battery is not staying fully charged up.

I put some belt dressing on the drive belt for the trucks alternator and it made the volt meter reading drop. I was not sure why that would have happened. Maybe some of the belt dressing over spray got inside the alternator wiring or something. Just guessing here. It may have just been a coincidence.

I just don't want to get stuck somewhere without a good battery. That happened to me a few years back when one of the battery terminals came loose and my truck stopped running. I finally figured out what was wrong and got a new battery terminal connector for the truck wiring and then purchased this new battery. I was lucky that I had my new portable Battery Power pack with me that night so that I could jump start my truck and get home without having to call for help. I got the terminal tightened as best I could and drove straight to Walmart and bought a new battery and a new cable connection. I then went straight home and installed both. That was 2 or 3 years ago and the battery has been working good until the little red battery low indicator light started coming on recently.

I took the terminals off and cleaned them real good and then connected them back on and then sprayed some protectorant on them. Some type of spray on terminal dielectric stuff that coats them and reduced corrosion.