1971 Mercury inline six not charging the cranking battery.

Theoutdoorsman

Senior Chief Petty Officer
Joined
Mar 6, 2003
Messages
669
Can someone help me troubleshoot. Where to start? Worst case scenario, what can I expect to spend on repairs? The motor runs like a demon. It just won't charge the cranking battery..... :-(
 

Franki

Lieutenant Junior Grade
Joined
Feb 16, 2002
Messages
1,059
Re: 1971 Mercury inline six not charging the cranking battery.

well, I am not familiar with your motor, but you can't quote cost figures till you have assertained what the problem is..<br /><br />do you have a multimeter or voltmeter? first step is to test the voltage at the battery before and after starting the motor, if there is an increase and the voltage is over 12.5 or so, you are probably ok, and the battery is clagged..<br />(Is the battery clagged?) (incidently if you don't have water muffs, or a big drum, don't start it out of water, and even with muffs, don't rev the motor much.)<br /><br />Verify the battery first, then test for voltage while running, once you know the charger isn't working at all, then you can start looking for specifics.<br /><br />rgds<br /><br />Franki
 

Theoutdoorsman

Senior Chief Petty Officer
Joined
Mar 6, 2003
Messages
669
Re: 1971 Mercury inline six not charging the cranking battery.

The voltage at the battery before and after starting the motor does not change.
 

Theoutdoorsman

Senior Chief Petty Officer
Joined
Mar 6, 2003
Messages
669
Re: 1971 Mercury inline six not charging the cranking battery.

The battery is brand new also.
 

mellowyellow

Vice Admiral
Joined
Jun 8, 2002
Messages
5,327
Re: 1971 Mercury inline six not charging the cranking battery.

sounds like a bad rectifier, about $35 and takes<br />5 min. to install. reccomend getting the service<br />manual and testing it first though. <br />good luck,<br />M.Y.
 
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