Charging issue or what?

[StingrayMike]

Been trying to find a ground that has been draining my battery. Bought a seloc manual (thats a whole different story). been chasing my tail on this one.
when running the engine, battery stays at 12.3 volts. voltmeter at helm displays 11.8 volts. over time, the voltmeter at the helm will drop down to 11 volts, but the battery stays at 12.3. took a reading at the main cable at the alternator, read 12.3.But at the small wire at the alternator, reads 11 volts.
I ran the boat for about 30 mins just on the battery (radio, engine blower, vhf radio, gps, navlights, courtesy lights). battery stayed around 12, but the voltmeter at the helm dropped down to 10 volts.

Now looking at the manual all this comes from the M1 fuse at the fuse block. It feeds the instrument panel through all the purple wires.following all the purple leads, it feeds the helm panel, as well as sends voltage to the alternator.

so i dont know what the purple lead to the alternator do? does it send voltage to the alternator to tell it how much it should output for charging?
and puzzled about the readings I am getting. I know the voltmeter could be off. I checked voltage at the back, and it was pretty close to what meter reads..

 

[ondarvr]

It should be in the 14 V range while running, 12.3 means the charging system isn't working. A fully charged battery will be 12.6 or so, 12.3 would be discharged. Depending on where the readings are taken they can be slightly different, there can be a slight line loss. Take the readings at the battery, if it never goes higher than 12.6 you have charging system problems.

 

[gm280]

From just reading you thread, It seem you have a lot of corrosion on the different terminals. If you read 12.3 volts at the battery, you should read 12.3 volts at the helm. The fact that you don't read the same at the helm means you have corrosion or something dropping the voltage from the battery to the helm. I say time to check every terminal connection including the battery to engine ground wire as well. So many forget you need a good ground for everything to work properly. If after you clean all the terminals and still have such a voltage drop, you have something draining the voltage off and you need to find out what. However you need to use the same meter to read at each place to rule out a bad meter. If the voltages do read different at each place, you have either bad connections or the wire itself... JMHO!

 

[StingrayMike]

The 1st thing I checked was for corrosion. I cleaned all connections, even remade some suspect cabes and put on some new terminals.
still getting same results.
I had the alternator tested at an actual alternator repair shop a few months ago and it was good.
so defiently going to get it retested. Now could that also be causing the low voltage to the helm via that
small connector?
will defiently check for any other connections

 

[gm280]

The 1st thing I checked was for corrosion. I cleaned all connections, even remade some suspect cabes and put on some new terminals.
still getting same results.
I had the alternator tested at an actual alternator repair shop a few months ago and it was good.
so defiently going to get it retested. Now could that also be causing the low voltage to the helm via that
small connector?
will defiently check for any other connections

Two things for you to check. First, are you using the same volt meter to read the voltages at different place and not reading with a meter at the battery and a voltage meter in dash at the helm? If you are using the same meter and getting different voltages from the battery verses the helm, you have a problem with something loading the voltage down and the wire should be getting hot, or at least warm to post those differences. As far as the engine charging the battery, it may be time to test the rectifier and regulator if your engine has a regulator... Because if you don't read any difference between running and non-running at the battery (voltage reading), you have a bad charging system...

 

[Grandad]

From just reading you thread, It seem you have a lot of corrosion on the different terminals. If you read 12.3 volts at the battery, you should read 12.3 volts at the helm. The fact that you don't read the same at the helm means you have corrosion or something dropping the voltage from the battery to the helm. I say time to check every terminal connection including the battery to engine ground wire as well. So many forget you need a good ground for everything to work properly. If after you clean all the terminals and still have such a voltage drop, you have something draining the voltage off and you need to find out what. However you need to use the same meter to read at each place to rule out a bad meter. If the voltages do read different at each place, you have either bad connections or the wire itself... JMHO!

Hi gm. I would expect to see a voltage difference between the helm and battery readings using the same meter. The helm position will see a voltage drop proportional to the length and resistance of the wire. As an example, a #12 AWG wire safely carrying 20 amps will have perhaps a 1 volt drop at the helm.
This is based upon a basic resistance of #12 AWG copper wire having a resistance of .0016 ohms per foot.
Voltage drop on a wire is equal to the amps it's carrying times it's total resistance.
Assuming a 1 way helm distance of 15 feet, the formula becomes:
15' x 2 x .0016 ohms x 20 amps = 0.96 volts
So, I'm not saying there isn't also some corrosion or another problem, just don't expect to read the same voltage at the helm as the battery when load is applied. - Grandad

 

[StingrayMike]

Two things for you to check. First, are you using the same volt meter to read the voltages at different place and not reading with a meter at the battery and a voltage meter in dash at the helm? If you are using the same meter and getting different voltages from the battery verses the helm, you have a problem with something loading the voltage down and the wire should be getting hot, or at least warm to post those differences. As far as the engine charging the battery, it may be time to test the rectifier and regulator if your engine has a regulator... Because if you don't read any difference between running and non-running at the battery (voltage reading), you have a bad charging system...

yes, I am using same meter at the battery, alternator, and helm. I checked the voltage going into the back of the helm voltage display, the helm display was only about .5 volts less than my mulimeter at the back of it. There is no regulator.
I think there might be a splice or two that I cant figure out how to get to. I think I have to remove the risers. Not looking fwd to that.


I took the alternator down and got it tested. It tested good, but he couldnt give me a printmout of the results, just siad it passed the 3 checks.

 

[bruceb58]

What are you working on?

The first issue you need to look at is why your alternator is not charging. First thing I would check is to make sure the wire that is connected to the excite/field terminal of your alternator has voltage on it.

Don't worry about the voltage drop between the engine and the helm for the time being. It's actually probably about right depending on what is getting powered.

 

[StingrayMike]

What are you working on?

The first issue you need to look at is why your alternator is not charging. First thing I would check is to make sure the wire that is connected to the excite/field terminal of your alternator has voltage on it.Don't worry about the voltage drop between the engine and the helm for the time being. It's actually probably about right depending on what is getting powered.

took the alternator to get tested at an actual starter/alternator repair shop......
it was bad.
so I got a new one on order, should be here in a few days, we will see if that was it, but not quite convinced that was the only issue. We will see when I get it replaced.