50 hp mercury charging over 18v into my battery

[glory4me]

I have a 1985 50 hp mercury 2cycle 4 cylinder outboard.

I got this outboard, with no history..

It was missing part time on one cylinder.. when it was not getting spark to the one cylinder, I checked voltage going and comming out of switchbox, it apeared to not have power comming out of switchbox,, So I got a new switchbox and ignition coil..

When I took out old coil. it had a broken steal under the boot..So I figured that was the beginning of problems for the outboard..

I had noticed the battery was getting charged over 16v

Now after I changed switchbox and ignition coil.. everything sound and works just fine,, but it is putting over 18volts into the battery..

I don't have a dva or a manual yet.. For me it make sence that stator is putting to much output.. So I am wondering if I might be correct to just change the stator..

Also I went on a 20 mile cruise with it yesterday. Everything appears to be working just fine except it has a high battery voltage over 18v (its a new marine battery)

For now I am just wondering how long this will last like this..also, do I need to change stator.. it has a rectifier , I changed that, it does not make a difference.

Thanks

 

[Laddies]

Re: 50 hp mercury charging over 18v into my battery

First check the system with a test meter the dash meters are not always accurate. Usually high voltage is caused by a loose or dirty connection or a battery that is a light duty or going bad.

 

[Jeep Man]

Re: 50 hp mercury charging over 18v into my battery

Test with a proper voltmeter and test with and without the battery connected. Proper charge rate for a marine battery is 14.2 volts. 18v will boil the battery and kill it in no time.

 

[emckelvy]

Re: 50 hp mercury charging over 18v into my battery

There is nothing wrong with the charging system. This is a 10 amps max, unregulated-type of output with a full-wave bridge rectifier. No regulator. Faster you go, the more voltage generated, to the limits of the system.

Simple solution is to turn the running lights on and in many cases that load will drop the voltage down to a reasonable level.

If that doesn't work, there are larger/later model motors using a rectifier/regulator combination. You can retrofit one of these to your motor and that will keep the voltage within a normal range.

Use the Search feature to find past threads with "regulator" and you'll get lots of tips regarding that modification.

HTH..........ed

 

[j_martin]

Re: 50 hp mercury charging over 18v into my battery

Test with a proper voltmeter and test with and without the battery connected. Proper charge rate for a marine battery is 14.2 volts. 18v will boil the battery and kill it in no time.

DO NOT try to run it without the battery connected. It can fry all kinds of electronics, like the oil alert, depth finders, dash instruments.

It's an unregulated system. The battery itself holds the voltage down to about 15 volts. If the battery is low on electrolyte, or worn out, or the connections are loose.

You need to check the battery and add water from time to time. Some water is used, but if maintained, not enough to adversely affect the life of the battery.

 

[glory4me]

Re: 50 hp mercury charging over 18v into my battery

I put a 50 watt light bulb and with the little running light on the skiff. those held the voltage down to 14.4v while running,

I think this outboard with a electric start, might have been set up for more power usage.

the post above affirmed what I was looking for.. thanks..

 

[j_martin]

Re: 50 hp mercury charging over 18v into my battery

I put a 50 watt light bulb and with the little running light on the skiff. those held the voltage down to 14.4v while running,

I think this outboard with a electric start, might have been set up for more power usage.

the post above affirmed what I was looking for.. thanks..

If 4 amps is raising the battery voltage to 18 volts, the battery is shot, or connections are bad. Check it out before you're stranded.

hope it helps
John

 

[gill]

Re: 50 hp mercury charging over 18v into my battery

install a regulator

 

[glory4me]

Re: 50 hp mercury charging over 18v into my battery

the best idea is the install a regulator..

As far as those who think the battery is shot,, or bad connections, ..

Is a brand new battery , and the connections are good.

the outboard is running at a fast idle right now, I have to do some tuning and get it down where it should be....thats probly part of the reason for high voltage,... I have not put a amp meter on it.. but doing the math.. it is putting out close to 4 or 5 amps.

I have used outboards for 40 years. I never had a mercury.

This one came with a skiff that I picked up with a good deal.
it had a bad switchbox and a broken ignigtion coil.. From changing those part..in the beggining, I was just wondering if somehow from those problems it may have caused the stator to put out more than it should..

after seeing these forums.. I can see that I am not the only one that has overcharging problems with my mercury..

thanks all for your input... have a nice xmas

 

[j_martin]

Re: 50 hp mercury charging over 18v into my battery

the best idea is the install a regulator..

As far as those who think the battery is shot,, or bad connections, ..

Is a brand new battery , and the connections are good.

Its charging more like 10 amps.

If you have 18 real volts at the battery, it is defective, likely a bad internal connection. REPLACE IT BEFORE IT BLOWS UP. (seriously)

I said real volts because the meter might be wrong.

hope it helps
John

 

[glory4me]

Re: 50 hp mercury charging over 18v into my battery

If you have 18 real volts at the battery, it is defective, likely a bad internal connection. REPLACE IT BEFORE IT BLOWS UP. (seriously)

I said real volts because the meter might be wrong.

hope it helps
John

I have tried two batterys on it, same thing
thanks

 

[Yepblaze]

Re: 50 hp mercury charging over 18v into my battery

Totally normal.

Maybe not good, but normal.

If it bothers you, do as suggested, by adding regulator, or load.