Voltmeter/Charging Problem

[slenglish]

I have a 1996 225 EFI Mercury Offshore, that runs ok...noticed the voltmeter guage showing less than 13 (Which is half of gauge, which goes from 8-18) when key is on, and when engine is running does not go up, goes down. Tested battery, was low, put on charger and hydrometer tested over 1200, battery appears good although both batteries are 7 years old. Does gauge indicate charging problem, if so HOW DO I CHECK ALTERNATOR OUTPUT TO INSURE THAT IS WHERE PROBLEM IS? or WHAT ELSE SHOULD I CHECK FOR A CHARGING PROBLEM? I have a small solar panel plugged in occassionally to ciggarett lighter, would that affect charging system?

 

[DJ]

Re: Voltmeter/Charging Problem

slenglish,<br /><br />Seven year old batteries will leave you.<br /><br />However, that's not the source of your problem. Get a hold of a voltmeter. Place the leads across the battery terminals, first without the engine running and then with.<br /><br />You should see at least a two volt difference.

 

[slenglish]

Re: Voltmeter/Charging Problem

Thanks...I did that and meter stays at 12.5, when engine is started it drops quickly to about 9 volts then back to 12.5...I have a small alternator under engine cowl and checked volts at the orange "booted" terminal on the alternator and without running I have 12.5 volts...and again when running same voltage. It appears wiring to battery (circuit) is ok....It looks like problem may be with the alternator...Is it a repairable / rebuildable unit like a car alternator or does one just replace it...Any thing else to check?