Alternater check

[SHAFT]

bbf with a 1 wire alternater , If I put a volt meter across the one post on the alternater and ground should I get a reading at idle ? I am getting nothing , my gauage is at zero and always has been could it be the gauage ? I just installed 2 new battries today also . Thanks

[Oldsquirt]

If you are measuring voltage between the output terminal of the alternator and ground, you should show battery voltage even with the key off. Trace the wiring from the output. Do you have a voltmeter in dash or amp meter? With an amp meter the output runs all the way to the gauge, through it and back to the battery. With a volt meter it will run more directly as it need not go through the voltmeter. The exact connections will vary depending on who wired the boat and how they decided to do so. There's more than one correct way. Typically, the output will go back to the same connection on starter relay that the battery positive cable is connected to. Follow the wires and check all connections.

[jbone]

You can check battery voltage and charging by putting the red wire from your tester to the positive on the batt and the black wire from your tester to ground. It should be in the 12 volt range, Once you start the engine the voltage should go up to about 13.2-13.6 or so, maybe higher. I'm not sure the what the minimum and maximum charging rates are. I'm sure someone will elaborate. You may have to rev the engine to get the alternator to start charging. If the volts don't go up, you could have a wiring problem or a charging problem.
To eliminate a wiring problem, you could check the charging voltage at the alt by connecting the red test wire to the charging post.
Make sure you have a good ground.
Hope this helps,
J

[Oldsquirt]

Just another thought since you mentioned having two batteries.......If you are using an electronic type battery isolator, you may have problems with the operation of a one-wire alternator.

[SHAFT]

I checked and I do have an ampmeter not a voltmeter in the dash , I do have a perko switch for the batteries which showes 1 , 2 , or both , I use the both and a thing that looks like a big heat sink which I assume is the isolator . So the ampmeter has 0 in the middle and 50 to the left and right at start up it goes up to about 30 to the right then back to 0 . What does the isolator do ? Should I run on one Battery and save the other for emergency ? Why would you want an ampmeter to me a voltmeter would be more useful to make sure your staying charged . I am not questioning the alternator I just thought with the new batteries I should check it too . Tomorrow I will try the voltmeter again from the alternator post to ground [ will this work with an isolator ?] for battery voltage .

[Oldsquirt]

Based on your post on Banderlog, your system operation seems to be normal. I'm not entirely sure why you would have an isolator and a Perko switch. The latter is basically a manaul verson of the former.

[SHAFT]

Thanks Oldsquirt and jbone I really appreciate all your input .