Normal volts at batery while running?

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Betterthannothin

Seaman
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Aug 4, 2010
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61
Long story short, I was towed in due to a dead batery. After getting a brand new marine dual purpose battery I fired up the engine and put a meter on the batery. I was getting 11.9 volts. I tooke my rectifier out to look at it and realized it had lots of corrosion of its internal components, so I got a new one. Now with the new one installed at idle I'm getting 15.5 volts. My concern is that I will cook the batery. I assume that somewhere around 13.5-14.8 is normal range. Any insight on this would be great. The motor is A 1986 merc 75 HP 2 stroke, 4 cylinder. Thanks in advance.
 
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Chris1956

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Mar 25, 2004
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Re: Normal volts at batery while running?

Those charging systems are unregulated. Since they put out minimal current (9A at high RPM), I would not worry too much about overcharging the battery. Your battery actually serves as the voltage regulator in that system.

Make sure your wiring is clean and tight, or the new rectifier will blow out.
 
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mr 88

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Nov 3, 2010
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Re: Normal volts at batery while running?

I do not disagree with Chris.I am running a 66 1100ss tower,unregulated with a dual purpose battery and no problems after one full season.There was a post recently about this and one of the answers was to use the older style battery that you put water in.I think what I read was they will take more of a charge without the extra voltage "backing"up into the motors electronics and frying them.Next year I will switch out batteries as I have other places to put that battery in.You may want to use the search icon to find that post,maybe two months old?
 
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mr 88

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Re: Normal volts at batery while running?

The post is now on page 16- Titled- " New guy with charging voltage question"
 
Silvertip

Silvertip

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Re: Normal volts at batery while running?

If the higher voltage bothers you, turn on some accessories and the voltage will drop a bit.
 
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sschefer

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Nov 13, 2008
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Re: Normal volts at batery while running?

Chris1956 said:
Those charging systems are unregulated. Since they put out minimal current (9A at high RPM), I would not worry too much about overcharging the battery. Your battery actually serves as the voltage regulator in that system.

Make sure your wiring is clean and tight, or the new rectifier will blow out.
Click to expand...

The correct and perfect response... believe it!
 
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Chris1956

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Re: Normal volts at batery while running?

A lot of the "sealed maintenance free" batteries can be filled with water, if necessary. Look around where the caps would normally be and you may find flush filler plugs. Sometimes these are under a gasket. Every two years or more, pry out the caps and fill with distilled water.
 
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Chris1956

Supreme Mariner
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Mar 25, 2004
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Re: Normal volts at batery while running?

Sorry, the fill plugs can be under a decal. I was not allowed to have coffee today.....
 
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Betterthannothin

Seaman
Joined
Aug 4, 2010
Messages
61
Re: Normal volts at batery while running?

Thanks for that chris, I will keep an eye on my battery. I cleaned up all the connectors a bit and everything is tight and looking good. I guess I'll go out fishing this weekend and see how she does.
 
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