Charging system problem

[SonnyOB]

Hi all. I have a 2007 sea ray 350 mag efi. I noticed that my voltage on the dash (smartcraft) showed 11.9 volts. I have a dual battery setup with perko switch. I checked the voltage at each battery (engine running)and got the same reading. I then checked voltage at the alternator engine off and got less than 1 volt. (Orange wire). With engine running it reads 25 volts! What the heck is going on here? Please help. Thank you.

 

[bruceb58]

Sounds like there is an open between the alternator and where that orange cable connects at the starter.

 

[SonnyOB]

That's kinda what I was leaning towards. Is that orange wire fused?

 

[bruceb58]

I am not sure on your engine.

 

[Bt Doctur]

Some use a 90A fuse link looks like a square plastic block at the starter post

 

[SonnyOB]

I'm going to check for that fuse. Should the alternator be replaced at this point?

 

[bruceb58]

It might still be good but running without a load is usually death to an alternator. You can do a quick check by just running a seperate10 gauge wire from the output of the alternator to the pos terminal of the battery right now to test it.

On engines that have that fuse, usually nothing else even works since the fuse is shared by both the alternator and the line powering the helm fuse box but I am not as familiar with what Mercruiser does.

 

[SonnyOB]

I'm going to try all that. Thank you

 

[SonnyOB]

Ok, I replaced the alternator to be on the safe side and followed the orange wire down to the starter. The wire was broken at the crimp on the connector. I made up a new wire with new connectors, 10ga, and hooked it all back up. Charging like a champ now. Thanks for the help.

 

[JoLin]

Glad it worked out for you, but you replaced the alternator without verifying that the old one was bad. I just finished troubleshooting the system on my son's car and determined that he had simply run the battery down accidentally (he left the stereo on). But, the car is 9 year old and the battery 3 years plus, so I followed the following steps...

Visual inspection of the battery wiring (saw nothing obvious)
Cleaned the batt terminals (a little dirty)
Checked fluid level in all the battery cells - all good
Charged the battery (Multimeter read 13.0 volts when my smart charger said it was 'FULL')
Let it sit overnight to let the surface charge dissipate (got 12.62 volts. Perfect)
Load tested the battery (gauge fell right on the CCA rating of the battery)
Tested the alternator (14.42 volts. Perfect)
Load tested the alternator (ranged from 14.2 to 14.5 volts with headlights and heater blower on. Perfect)

The whole process took 12 hours or so (mostly letting the battery sit overnight), but everything got a clean bill of health and I can confidently give the car back to him and just tell him 'don't do that again' :joyous:

Not picking on you at all, but $50.00 worth of test equipment (digital multimeter and battery load tester) can save you many hundreds over a few years.

My .02