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Voltage question 318

B

bfiesta

Member
"I was tightening up the bolts

"I was tightening up the bolts on my valve covers the other day... and like a dumb-a** I forgot to turn off my batteries. I dropped the socket wrench and it touched the back of the alternator. Low & behold... SPARK! While it was only a quick zap... Now when I run the engine at idle the voltage looks good at around 13-14 volts. But when I rev the engine into higher RPMS it will increase to 15-16 volts (closer to 16). Any ideas on what I may have fried!?!

Repeating to self, rocking in my chair, trying to find my happy place: "Always turn off the batteries, always turn off the batteries""
 
"Time for an alternator rebuil

"Time for an alternator rebuild. Got a good shop if you live near Allentown, PA or want to mail it in.

Jeff"
 
"This brings up another questi

"This brings up another question I have... what would be the correct voltage and amperage output? I only have amperage gauges and they are both in positive while the engines are running - but the batteries do not seem to be charging very well from the alternators.

I ran my battery selector in 'both' instead of 1 or 2, would that be the problem?"
 
"No, but it'll take longer

"No, but it'll take longer to charge the two batteries vs. only one. Use a handheld volt meter and look for 13.5 to 14.5 volts when it should be charging. Harbor Freight sells meters for 5 bucks--great if you drop it in the bilge or overboard.

Also, with the engine off, look for about 13 to 13.6 volts from EACH battery (selector switch on position '1' or '2'). If one battery is lower after you've zapped them both for a period on 'Both' then you have a bad battery.

Jeff"
 
"Just a quick follow-up... sin

"Just a quick follow-up... since I am sure there are other newbs like me out there: Pulled the alternator and took it to a local re-builder (DC Electric, Chico WA). Put it on the stand and it ran and charged just fine (not bad for a 1977 alternator).

I fried the voltage regulator. Easy and less expensive fix. However, I am keeping the old as a spare and have ordered a one wire Arco (part# 40112) alternator.

Also learned that the alternator really doesn't kick in charging until you rev the engines a bit past idle.

My rebuilder also warned me that they rebuild marine alternators all the time becuase people turn the battery switches while the engine is running. This burns out alternators faster because all of that voltage suddenly, for a brief second has no where to go."
 
"..."My rebuilder also war

"..."My rebuilder also warned me that they rebuild marine alternators all the time becuase people turn the battery switches while the engine is running. This burns out alternators faster because all of that voltage suddenly, for a brief second has no where to go."


Correct! You can flip the Perko-type battery switches from position 1 to 2 or All and back without a problem, but NOT to Off then back on.

Jeff"
 
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