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Old 10-08-2019, 12:23 PM   #1
lalkie
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Default Generator Charging

I have a 29 ford pickup since the early 70,s. I recently changed it to 12 volt negative ground. After a while I noticed the generator was charging at over 10 amps during the day. It was as charging at 5 amps prior to the voltage change. I reduced the charge to 5 amps at 12 volts. I am unsure why there was a change. The only thing I can think of is the larger 6 volt wiring has less resistance. Are there any electrical guru's that have a reason for the increased amps. Just wondering. Larry
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Old 10-08-2019, 02:35 PM   #2
wmws
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Default Re: Generator Charging

The term Ohm's law refers to one of the fundamental relationships found in electronic circuits: that, for a given resistance, current is directly proportional to voltage. In other words, if you increase the voltage through a circuit whose resistance is fixed, the current goes up.
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Old 10-08-2019, 05:42 PM   #3
Purdy Swoft
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Default Re: Generator Charging

If you can adjust the third brush for the desired amount is the important thing .
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Old 10-09-2019, 12:06 PM   #4
Badpuppy
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Default Re: Generator Charging

Third brush is basically a current setting. Since 12V components require only half the current, the setting for 6V will be twice that required for 12V.

If you used a dropping resistor with your original coil, it will require the same current and your 5 amp setting would be proper (the series resistor will dissipate the same amount of power as the coil in useless heat). If you replaced the original coil with a 12V type, however, then 3 amps should be about right.

Check your battery voltage while charging - 14.4 volts would be ideal; at 15.8 volts the electrolyte will begin to hydrate from overcharge. Note everything varies with engine rpm. Replacing the cutout with a modern regulator is a good idea.
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Old 10-09-2019, 12:52 PM   #5
Purdy Swoft
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Default Re: Generator Charging

I use the Fun Projects voltage regulator with the original generator on my twelve volt converted model A . John Regan recommended that I set the third brush for a maximum charge rate of 10 amps . The voltage regulator will only allow a 10 amp charge on demand . In other words it would only charge 10 amps when the lights or other high draw accessories were in use . I chose to use a three OHM coil than clutter up the firewall with a hot resister . Resistors can get pretty hot and it is difficult to hide in a safe way .
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Old 10-09-2019, 03:32 PM   #6
Purdy Swoft
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Default Re: Generator Charging

I agree with Badpuppy in post number 4 . Twelve volt components require about half the amps that six volt components require . That takes a load off the generator . The generator will run much cooler and last longer on twelve volts . I remember a few years ago the very mention of running the original generator on 12 volts would have some fainting , left and right . Badpuppy knows his stuff !!!!!!!
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Old 10-09-2019, 05:25 PM   #7
Patrick L.
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Default Re: Generator Charging

'on 12 volts would have some fainting , left and right'


LOL, thats right. Experience is a good teacher.
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Old 10-09-2019, 06:22 PM   #8
Purdy Swoft
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Default Re: Generator Charging

I thought that was a good one .
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Old 10-10-2019, 12:11 PM   #9
rotorwrench
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Default Re: Generator Charging

The only drawback with the 3 brush generator is that it can still only put out just a set amount of current no matter what the voltage is. It can put out no more than it can on 6-volt or 8-volt. Most folks that go the 12-volt route usually do so in order to operate more 12-volt accessories. The old 3 brush genny can't add more for more electrical stuff.

Folks that use the electronic voltage regulators will always make the generator last longer since it only puts out what the system needs at any given time. When the battery is charged, it's almost freewheeling.
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Old 10-10-2019, 01:06 PM   #10
Purdy Swoft
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Default Re: Generator Charging

Yes , the generator can only put out so much . Ten amps maximum charge is all that is needed for a 12 volt conversion when using the twelve volt Fun Projects voltage regulator . I use the 35-35w halogen bulbs that fit the original sockets with the generator when running 12 volts . If I need more amps for 55-60 watt halogen headlamps I use an alternator. I prefer to keep mine original appearance for the most part . That's why I mostly use the original generator with 12 volts . The generator charges the battery with amps . Voltage is controlled by the battery that is used .

I prefer 12 volts for a more powerfull electrical system, quicker starting and brighter headlamps. Twelve volt batteries seem to charge quicker and holds charge longer . Twelve volt batteries and components are easier to find . No wiring changes are needed as long as the system remains positive ground . There is no obvious visible change under the hood . If in good tune the engine will start so quickly the starter will hardly be heard .
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