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Changing ampmeter to a voltmeter

Your old Chris-Craft electrical system can be a challenge. If it runs on "juice" pose your questions and offer your advice here.

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johnnyeal
Posts: 7
Joined: Tue Jun 06, 2006 11:23 pm

Changing ampmeter to a voltmeter

Post by johnnyeal » Mon Apr 09, 2018 11:30 pm

I am trying to confirm wiring
I terminated the wires to the ampmeter
Ran a new wire from the on post of the ignition to the positive post on the voltmeter and a new wire from the ground to the negitive post on the voltmeter
It reads 8 volts and not 12.6
Battery test at 12.6 with a multimeter on the battery post
Shunt, voltage regulator not bothered except to terminate the old ampmeter gauge wires behind the instrument panel
Help

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mbigpops
Posts: 328
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Location: Eastern Massachusetts

Re: Changing ampmeter to a voltmeter

Post by mbigpops » Tue Apr 10, 2018 7:18 pm

Okay so what are trying to read on the voltmeter - battery voltage or running voltage from the alternator ?

If you want to read the battery voltage then you can connect to the ignition switch as that derives from the battery. If you want to read the alternator running voltage then you cannot connect to the ignition switch but need to connect a wire from the alternator to the voltmeter. This may have been the wire that originally went to your ammeter.

The other question is why are switching in the first place ? The ammeter tells you a lot more about what is going with either current draw or charging then just seeing what the voltage is at.

Either way is looks like you are dropping voltage from the starter to the ignition switch. You need to measure the voltage going from the battery to the starter to the ignition switch to see where you are losing voltage. Maybe the start relay ?

Mark
1953 CC Rocket Runabout "Rocket Man"

Denis D
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Location: Northern New Jersey

Re: Changing ampmeter to a voltmeter

Post by Denis D » Wed Apr 11, 2018 12:18 pm

Are you sure your Voltmeter is calibrated correctly? With the ignition on and the meter showing 8 volts, connect your multimeter to the voltmeter terminals to confirm the reading. If it is 12 volts then your Voltmeter is off, if it is 8 volts then you have a high resistance connection somewhere between the battery and the gauge which could be on the hot or ground sides.
BTW - When checking the voltage at the battery, put the leads on the cable clamps, not the battery posts as it is not uncommon to have a bad connection there. You should also have the ignition on so there is a load on the battery.

Denis D
Denis

1948 17' deluxe runabout

johnnyeal
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Joined: Tue Jun 06, 2006 11:23 pm

Re: Changing ampmeter to a voltmeter

Post by johnnyeal » Thu May 17, 2018 2:25 pm

Re: Converting Ampmeter to Voltmeter
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Post Thu May 17, 2018 1:19 pm

I still have not solved this question and read only 10 volts on the voltmeter and battery reads 12.2. I have the old voltage regulator, alternator and shunt still installed. Would these items be interfering with the voltage reading?

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mbigpops
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Location: Eastern Massachusetts

Re: Changing ampmeter to a voltmeter

Post by mbigpops » Fri May 18, 2018 8:00 am

Well if you are expecting someone to reply and say "oh a 2.2V drop is definitely the ......" you may not get it.

In the mean time I would suggest that you either remove the possible offending items that you mentioned or jumper them out one at a time and see when and if the voltage goes back up to 12.2V.

If you do that and nothing changes then you may have a bad gauge.

Mark
1953 CC Rocket Runabout "Rocket Man"

Denis D
Posts: 81
Joined: Wed Dec 02, 2009 6:13 pm
Location: Northern New Jersey

Re: Changing ampmeter to a voltmeter

Post by Denis D » Sun May 20, 2018 12:47 pm

Can you post the wiring diagram for your boat?
Denis

1948 17' deluxe runabout

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drrot
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Re: Changing ampmeter to a voltmeter

Post by drrot » Sun May 20, 2018 6:45 pm

cc Wiring_Diagram 1952.jpg
Here is one from 1952
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Jim Staib
www.finewoodboats.com

1931 Chris-Craft 26' #898 http://www.finewoodboats.com/1929%20Chris26.htm
1929 Chris-Craft 28' #3107 http://www.finewoodboats.com/1929%20Chris28.htm
1947 Penn Yan 12' Cartopper WXH474611
1950 Chris-Craft 22' Sportsman U-22-1532
1957 Chris-Craft 26' Sea Skiff SK-26-515
1968 Century 17' Resorter FG-68-174

Denis D
Posts: 81
Joined: Wed Dec 02, 2009 6:13 pm
Location: Northern New Jersey

Re: Changing ampmeter to a voltmeter

Post by Denis D » Tue May 22, 2018 2:34 pm

That doesn't appear to be the correct wiring diagram, he says he has an alternator and regulator, not a generator.
Denis

1948 17' deluxe runabout

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