General Charging Question - 1965 Mercury 350

65fabuglas

Cadet
Joined
Mar 1, 2012
Messages
12
I have an old 2-stroke Mercury engine; it has an electric start and a pull start. (Appears electric start was an extra option)

My question, was the charging system on this motor intended to be able to recharge the battery? (Or does the motor only produce electricity in order to power the coil for the spark plugs. )

I am only getting about 12.5 Volts accross the battery when it is running. I wanted to verify that the system is actually capably of re-charging the battery, before take the flywheel off and inspect the coil, etc.

I have a lame Sealock manual that isn't worth the paper it is printed on- I need to try to find a proper merc manual for this vintage.

Thanks in advance!

1965 Mercury 350 - 35hp
Serial#1900802
 
M

Maxz695

Guest
Re: General Charging Question - 1965 Mercury 350

I would have to think that if the electric start setup was originally part of the engine that the rectifier would produce the output necessary to charge a battery. Common sense would indicate this. increased RPM should produce more volatge for the charge. It will be between 12 V and 14 volts it idle. Check the voltage with the increased speed and see if the volts build up witch could take some time to aquire.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: General Charging Question - 1965 Mercury 350

Here in N. Texas on a given day 12.75 volts is a fully charged battery.

If the battery discharges, the alternator puts out voltage that has to exceed the existing battery voltage to force current (juice) back into the battery. Therefore the alternator voltage has to be higher. Alternators are great because they develop their voltage at low rpms so you have good charging current while at idle, unlike the old generators which would actually draw current at idle. The alternator voltage curve jumps up fast and has a long slowly rising slope as a function of rpm.

Most alternators with regulators will put out up to 14.5v tops as the battery is at the peak of it's charge. Unregulated will go up to 16v in some instances.

At 12.5v your alternator is not charging your battery!

Mark
 
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