08-08-2020, 08:10 AM | #1 |
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12v amps gauge
can I use a stock 6v amps gauge in 12v neg ground system?
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08-08-2020, 08:34 AM | #2 |
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Re: 12v amps gauge
Yes, reverse connections for neg ground.
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08-08-2020, 08:38 AM | #3 |
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Re: 12v amps gauge
Yes, although if your going to run a high current alternator you may want a shunt across the ammeter to reduce its throw. Overdeflection will kill the ammeter. An original ammeter is not something you want to waste, the repros aren't so good.
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08-08-2020, 05:26 PM | #4 |
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Re: 12v amps gauge
ok reverse wires. alternator goes to +?
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08-08-2020, 08:56 PM | #5 |
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Re: 12v amps gauge
Using a shunt across the ammeter pretty much makes the amp gauge non responsive.
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08-09-2020, 08:29 AM | #6 |
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Re: 12v amps gauge
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Forget a shunt. Just makes normal battery current hard to read. Use common sense instead: Sure, if you switch on your Blazing Baja Beams and Behemoth Boom Box with the engine off, you'll likely peg the meter into the Far Far West. Don't do that. |
08-09-2020, 09:06 AM | #7 |
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Re: 12v amps gauge
Current draw out of the battery and charging current should be less on a 12 V system compared to a 6 V system. Assuming all the loads (horn/starter, lamps, etc) are proper for a 12 V system.
So the gauge should be OK but most likely will read less. The gauge does not care what the battery voltage is, just the load/charging amperage. |
08-10-2020, 02:10 AM | #8 |
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Re: 12v amps gauge
Most alternators will put out at least 35 amps immediately after starting.
Install an aftermarket ammeter from Model A parts dealer with 30/30 reading. They look just like the 20/20 original except the higher amp readings. |
08-10-2020, 06:12 AM | #9 |
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Re: 12v amps gauge
To the OP: I agree with Badpuppy's comment, it is possible to use the stock 6 volt ammeter in a 12 volt system by reversing the leads.
This is off topic somewhat: I installed an AC unit in a recent build of a touring car. Every time the AC compressor clutch would engage, the needle would peg...hard. After a few days, the needle disappeared as it was knocked right off the pivot points. I did not know what size shunt to install so I installed a second ammeter under the hood to split the load. Both meters show a good draw when it starts...just short of pegging but so far, I have not lost sight of anymore needles. Anyone have a guess of what size shunt is needed based on my description? Thanks Guys. Good Day! Last edited by Dave in MN; 08-11-2020 at 04:39 PM. |
08-10-2020, 10:25 AM | #10 |
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Re: 12v amps gauge
Agree with Dave-in Minn. The current draw of a AC is almost constant load of 25/30 amps depending on the AC clutch cycling. That continuous load will cause the 30 amp meter to get hot because it is at the top of the load rating. On a cross-country road trip one of our cars, AC equipped, burned the amp meter up. Mine got very hot to the touch. I made a temporary shunt using 6 foot #16 wire wrapped around a 3/8 dowel approx. 3" long. It works well. First start of the engine the amp meter indicates about 5 amps charge very briefly.
Am experimenting to create a shunt that will indicate a charge of about 10/15 amps with full AC and Headlights load. If you have already done this please message me.
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08-10-2020, 08:38 PM | #11 | |
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Re: 12v amps gauge
Quote:
Charlie Stephens |
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08-11-2020, 12:15 PM | #12 |
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Re: 12v amps gauge
The ammeter shows the amps that the generator is putting out , not the voltage . I use the same ammeter with 12 volts that I use with 6 volts . The original unmodified generator will charge a twelve volt battery with no problem . I use the Fun Projects 12 volt voltage regulator that takes the place of the cut out . As has been said , the generator doesn't know the difference because the generator charges in amps . Generator out put can be controlled by the adjustable brush in the generator . Pushing the adjustable brush downward toward the ground raises the amperage out put . Raising the adjustable brush upward decreases the amperage out put . I have used the 30 amp ammeter when using the 60 amp alternator just for good measure . High amperage out put charges the battery quicker . A voltage regulator , when used prevents overcharging the system .
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08-11-2020, 12:16 PM | #13 |
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Re: 12v amps gauge
I never need a shunt .
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08-11-2020, 12:22 PM | #14 |
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Re: 12v amps gauge
Use nichrome wire to make an ammeter shunt. A good original ammeter is something you don't want to ruin. Size the shunt for the deflection you want, use an inline ammeter to give you the calibration factor.
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