3.0 mercruiser battery power issue

[Ayellaone]

While out on my 89 sea ray 160 br that has 3.0 mercruiser with alpha 1 outdrive, the gauge for volts shows right at 10. I turned the boat off and almost killed my battery trying to restart the motor about an hour later. Luckily I had a second battery and jumper cables that I used to combine for starting power. What should the alternator be producing as for voltage? I am worried that my alternator is not creating enough volts to charge the battery when running. Also, if it isn't producing enough voltage, can I do something as for maintenance or cleaning that will increase this?

 

[fishrdan]

I would check and make sure all battery and alternator cables are clean and tight.

10V is a completely depleted battery, and draining a battery to this point is really bad for the battery. Charge the battery back up and have it load tested. If the battery has removable vent covers, remove them and check the electrolyte level. A dry/dead cell could cause the battery to read low, into the 10V range.

When the engine is running, over 1000-15000RPM to get the alternator to "cut-in", the alternator should put out around 14V to charge the battery (13-14V). You can also take the alternator off and have it tested.

 

[Ayellaone]

thanks for your help. I have the battery on the charger now. I put it there this morning since I have had it in my truck been for a week. Where does the gauge read from?

 

[thumpar]

Check all your cable connections. I would also pull the alternator and take it to a close auto parts store. Pretty much all of them can check it in just a few minutes.

 

[midcarolina]

Checking the alternator is very easy to do......... first do as others said and clean your connections, then check your static battery voltage with a digital multi meter (everyone should have one) put muffs on drive start engine, while engine is running check voltage if voltage is 13-14 volts while running alt. is good

 

[Silvertip]

It doesn't matter where the voltmeter reads from, It could read directly from the battery, the alternator, the "B" terminal on the ignition switch or the "I" terminal on any of the other gauges. It is reading the electrical system voltage. If it reads 10 volts it is very likely the alternator is not charging. Gauges are there for a reason. Learn what they are for and what is normal and abnormal. Oil Pressure for example is not an oil LEVEL gauge. It's purpose is not to tell you to add oil. That's what a dip stick is for. Oil pressure is delivered by the oil pump that circulates oil through the engine. Low oil pressure is an indication that something is wrong internally in the engine.

 

[Ayellaone]

I understand what the gauges are for, I was just wanting to know more about how system works. I will be putting the battery in and putting it on the river either tonight or tomorrow. If I lose voltage, I will take the alternator off and have it checked at an auto parts store. Thanks for every bodies help. I will repost when I find out what is wrong.