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Alternator, Regulator or Gauge?

P

pwskicat

Regular Contributor
1995 Mercruiser 350 Magnum Tournament Ski, 460 hours. At wakeboard/ski speeds (18/30 mph) the battery gauge is pinned to the top reading, 16V. Is this normal? I have a multi tester if checking is required. Just need a how-to on the procedure.

Many thanks for your help, PW
 
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assuming your battery gauge is somewhat accurate, no, it is not normal. It should be a Mando 55 or 65 amp unit.

usually the fastest was to fix it is to replace the alternator....piece parts to do the repair have become a pain to source at a reasonable price. if you get a replacement, you can repair the old one at your convenience (or send it out for overhaul).

the full troubleshooting process spans several pages in Merc Manual #17...
 
Thanks, Mako. I'll run the tests per the manual and report back. There is a alternator/starter shop in my area with a very high google rating. Hoping to keep the money local if a new or reman alternator is in the cards.
 
if you have a shop close by, you should be ok....around here, most do a flat rate fee/exchange....if you insist, they will rebuild your core....new bearings, brushes, clean up the slip rings and check the diodes, stator and rotor...
 
Talked to a guy at the shop. He said simplest test is A) With ignition off, put positive lead to alternator output and negative to ground. Meter should read battery voltage, which was 12.66V on meter. B) Start engine and run @ 2k rpm. Voltage should jump 2 volts. My test read 15V. Is my alternator OK? Tks.
 
15VDC is a little high...should be 14.7 max.

may be ok as long as it doesn't vary widely as you spin it at different rates...

I'd say you should also verify it delivers current to the battery, which will vary with the load applied...
 
It's overcharging and will cook the batteries. The VR failed and you need to rebuild or replace your alt.
 
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