battery charging on the water

[1kickpic]

i want to know that my Merc 850 is charging my battery in operation. What should i use, a voltmeter or an ammeter? will the hookup of the meter just go directly to the positive and negative poles of the battery? when i hook up a voltmeter to the battery poles, the obvious reading is 12 volts. what will (or should) the reading be when the motor is running? will it charge at idle speed, or do i have to run at higher rpm's before it is actually charging? this may sound over simplified, but all i want to do is look at this meter and be assured that the motor is continually charging the battery. what readings (voltmeter/ammeter) will tell me that the battery is being charged properly? also, it does take power to operate a meter (which, if left connected to the battery, will drain it if not shut off). should i put an on/off switch to the meter and be able to check this only when i want to?

 

[Clams Canino]

Re: battery charging on the water

If the battery is already fully charged on a charger, you need to take the boat out on the water and observe the voltmeter at WOT. It should rise. DON'T rev it in the driveway.<br /><br />Other than that, you can disconnect and ohm out the rectifier as per the manual. If your not charging it's almost always the culprit.<br /><br />-W

 

[waterinthefuel]

Re: battery charging on the water

A way I found to safely check voltage for an engine at all speeds, if you have a depthfinder that shows voltage and isn't hooked up to the cranking battery, temporarily hook it up. Then take your boat all the way to WOT, watching the voltage. I did it this weekend for my little 28 and it goes from 12.4 at idle to over 16 volts at cruise. The water was too rough to go to WOT, but I figure it's staying below 18 since my depthfinder has an 18 volt high-voltage shutoff.<br /><br />If you don't, I advise you to just jump the battery terminals with a voltmeter and have a friend read it off to you as you accelerate.

 

[Solittle]

Re: battery charging on the water

kick - Use a volt meter. They are usually on only when the ignition sw is on. The voltage readings should be per the earlier posts.<br /><br />You should also have a hydrometer as this tells you the condition of the battery - a fully charged 12 volt batter does not necessarily hold a charge for long if it is not in good condition. Check the level of water from time to time & use distilled water if you need to add.