1986 75hp merc high charging voltage

[Jet tracker]

Took the boat out for the yearly test run and was noticing 16 volts on both of my battery gauges when running wot. I have to 28 series deka dep cells running through a marine switch with separate gauges on both so I dont believe my gages are off. Both had been on trickle charge all winter with full voltage in them and my charger will diagnose a bad cell so I dont believe I have a bad battery. Does this have a voltage regulator or just a rectafire?? I have a mercury bible for this motor and I cant seem to find a voltage regulator. If it dosent is this going to hurt anything and what would cause this all of a sudden spike in voltage.

 

[racerone]

Just a rectifier.-----Your batteries may be the issue.----Ordinary starting batteries may not show that high a voltage.-----Ask your local boat shop.

 

[Jet tracker]

So replacing the rectifier will not solve anything bc it dosent regulate voltage. A bad cell in one batterie will cause high voltage tho. These aren't starting batteries there all out marine deep cells.

 

[The Force power]

You could get the batteries tested first to eliminate that, do you have 16 volts at the batteries and where is the volts being measured? right after the Rectifier OR the battery-terminal

An increase in voltage from the Rectifier is because the current can't flow to somewhere or not being accepted(battery
and yes a Rectifier is just that; converting AC-volts to DC-volts, a Voltage-regulator converts AC-volts to DC-volts and limits the current output.

16 volts output a WOT is not that strange, but it needs to be brought down by being absorbed into the batteries.

 

[jimmbo]

What kind of Battery is a 28 series deka dep cell? Wet cell? Gell cell? AGM?

 

[dwco5051]

Check and be sure you battery connection are clean and tight. My last high voltage problem was a corroded battery connection.

 

[QBhoy]

Get a proper meter across the batteries first off. Gauges are pretty rubbish.

 

[Jet tracker]

There just a standard no maintenance battery. 29 series wich is the series size of the battery in other words there big. There is a gage on my fish finder that is hooked to one bat and a gage on my dash that is hooked to the other battery so yes I understand gages can read wrong but to get the same reading out of both of them I dont believe is a coincidence. One battery is 3 years old and the other is 4 so I am not disagreeing with a bad battery. If I could finish my honey do list around the house I could have these things tested b4 walleye opens next weekend

 

[Jet tracker]

They are deep cell marine batteries

 

[Jet tracker]

I just put a brand new starter selinoid on it also that wouldn't have anything to do with it would it??

 

[jimmbo]

Maintenance Free Batteries are something to avoid on unregulated charging systems like the one your outboard has.