Battery or Rectifier

[firedog978]

I am wondering if I have been chasing a ghost? About a year ago I purchased and installed two new batteries. I believe it was about that time that I noticed my dashboard amp gauge reading quite high (16 - 18 @ WOT). I looked at all my electronics to see if they were reading high as well. None were. They were all in normal range. I was NOT blowing any fuses either. Nor were any accesories failing or acting erratic. I even checked all fuses inline on my onboard 2 bank charger. Nothing appeared wrong except that dash gauge reading. Also, the gauge reads different amps as expected with throttle up, additional accesories on or off etc.. So, I am pretty sure the gauge is good.

Shortly after this started, research indicated a bad Voltage Regulator. I changed it out for a new one. I did NOT change rectifier or stater. Still had everything as described above after new VR.

So this morning with time to do some research, I checked rectifier and stater indications of being bad. Well, here's where I think I stumbled onto something. One of the IMPORTANT NOTES about rectifier replacement (which I have not changed) was TO NOT USE A MAINTENANCE FREE BATTERY with rectifier of 9 amps or more.

I do have a maintenance free battery (new last year), in use as the starting battery. All my electronics (reading correct amps) are on that battery. So, my question is; Is it likely that my maint. free battery is the problem?

And yes my trolling motor battery is not maint. free so I could swith them and see if problem solved. But before I spend that time unhooking all wires and moving batteries I'd like to see if any of you know or have had a similar happening.



p.s. Sorry for such a long post. And, all feedback is appreciated.

 

[Dave Muniz]

I'm usually a lurker here as most people know more than I do but I'd like to chime in here.



Electrical issues can be a bear to track down.



Interesting topic and good observations on your part to troubleshoot this.



You don't mention what kind of outboard and HP you have and when you say "maintenance free" battery I assume you mean an AGM type of battery.



What I think is happening is the charging system on your outboard is not rated to charge AGM types of batteries.



Most onboard chargers are rated to charge different battery types but I don't think outboard motor charging systems are.



This is good info to know as I was about to buy a new starting battery for my boat and was thinking of using an AGM type of battery.



Thanks for bringing this up.



What leads you to believe the rectifier and stator are now bad? Do you think the increased amps burned them up?



I would switch the batteries and see what happens.

 

[Lamar Gilbert]

I would suspect your panel meter is reading voltage, not amperage. I would check the voltage at the battery with a volt-ohm meter and see if the panel meter is reading right.



The charging system in your motor only supplies voltage to charge the battery and does not know what kind of battery it is connected to.



Good luck.

 

[Dave Muniz]

I agree with lamar that the guage is probably reading volts.



After some internet research the Optima batteries website says the recommended voltage for recharging from an alternator is 13.65-15 volts, no amp limit.



From a charger 13.8-15 volts, no amp limit



See this:http://www.optimabatteries.com/us/en/support/battery-care/charging/



Don't know what brand of battery your using but I would also see if I could test how much voltage your alternator is putting out.

Gauge may be off.

 

[firedog978]

Thank you both for responding. You're right, I inadvertinely typed amps instead of volts! I should have caught that as I proof read.

The outboard is a 75 HP Mercury 2 stroke, 3 cyl., 2001. The battery is not an AGM, just a sealed wet cell Marine starting battery.

I'll get a reading from the Voltage Regulator. If it reads properly I will switch the batteries and see what it reads at the gauge afterward. I think the next step after that will be to to change the gauge.