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Overcharging Mercury 50 -- 1974 model

DLancer7676

New member
Our boat mechanic said our engine was putting out 18 volts and should be putting out about 12 volts. He did not have the equipment to check this out and repair it. Can anyone tell me what problems can occur with this condition and how to repair it? Thanks.
 
Rectifier on the way out.These old Mercs did not have a regulator so expect to see 16v,18v a little high,I switch on a few running lights to pull the voltage back.The battery is the regulator which is why the type water/acid type battery is needed.
 
most stators produce around 17 to 19 volts. the voltage is reduced at the rectifier. if it checks high at the battery then replace rectifier.
 
haventaclue spoke the keyword here...you do not want a sealed maintenance free battery or a gel battery on this motor..you want an old type where you have to add water...there is no internal discharge on the new batteries and they will take what ever the rectifier puts out...on a regulator(which you dont have) the output will be regulated to 14.8 volts...on a rectifier only system it will run higher on a fully charged battery because it is not regulator but not 18 volts with the proper battery..
get yourself a new mechanic...a fully charged battery should put out 12.7 volts...any kind of charging system will exceed that...
 
I've gone to voltage regulators to prevent overcharging the battery I use (which is a tiny, lawnmower deal). Got mine off eBay for under 30 bucks. Lots of them available for lawn mower engines and etc.

Jeff
 
Our boat mechanic said our engine was putting out 18 volts and should be putting out about 12 volts. He did not have the equipment to check this out and repair it. Can anyone tell me what problems can occur with this condition and how to repair it? Thanks.


Thanks a bunch for the ideas. I have another boat mechanic who I am going to bounce these suggestions off of to see what the best solution would be. --DLancer:)
 
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