Help!..1978 Merc20hp Charging System Question

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ol20horse

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May 27, 2005
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I'm trying to get the charging system working on my 1878 20 hp(200) electric start. I didn't have any voltage at first so I replaced the rectifier and now I have anywhere from 14-22 volts at the battery cables depending on RPM. Is this how it should be??? Seems like it should be regulated around 14volts to me. Do you have to polarize the rectifier somehow? Thanks!
 
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Laddies

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Sep 10, 2004
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Re: Help!..1978 Merc20hp Charging System Question

You must have a battery hooked up to test voltage it should have a steady rise in voltage at normal operating RPM they will peak at 14 to 16 volts depending on the battery capacity
 
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ol20horse

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May 27, 2005
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Re: Help!..1978 Merc20hp Charging System Question

I checked it with the cables connected and it stayed right around 12.2 volts. I do have a rather large deep cycle marine battery running the show, will that effect the charging cycle?
 
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emckelvy

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Jan 16, 2004
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2,506
Re: Help!..1978 Merc20hp Charging System Question

This type of charging system has no voltage regulator and voltage output (to a max of approx 10 amps) is totally dependent upon system load.<br /><br />BTW NEVER run this motor without a battery connected or you may pop the rectifier.
 
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