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RE: Ammeter Wiring, 12V

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Chobber69
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RE: Ammeter Wiring, 12V

#1

Post by Chobber69 » Sun Jun 10, 2012 10:38 pm

Figuring to use an ammeter, on the chop; it's a 12V system, 2brush gen w/solid state regulator (looks like the old mech version). The diagram in Clymer (diagram 17, page 47) has a generator system test schematic; don't believe it's meant as a perm setup though. My best guess, would be to have the "+" terminal on the guage, go to the "+" side of the batt; using 12-14ga. wire (with a 20-30 fuze). The "L" terminal on the guage would then go to the "acc" terminal on the ignition switch? Got me stumped; also worried about the guage becoming a torch (hence the fuze). It would probably be easier, to mount a volt meter however would like to keep it old school i.e. to measure voltage system flow vs. batt voltage alone. Any assistance, greatly appreciated; haven't seen a thread on this one specifically.
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Re: RE: Ammeter Wiring, 12V

#2

Post by BlainesGarage » Sun Jun 10, 2012 10:59 pm

Chobber,
I'd recommend putting it on the negative side
of the battery, in place of the ground wire, no fuse required. This way you
can run a wire from the battery to where ever
you chose to mount the gauge, and the other
wire could be connected to any neaby good
ground. This way if the wire to the battery
would short to ground, no foul, everything would still
work fine except the gauge. Just be careful not to
route the wire near any existing wires and you
wont have any problem.

Blaine...

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Re: RE: Ammeter Wiring, 12V

#3

Post by Chobber69 » Mon Jun 11, 2012 12:02 am

Blaine: appreciate the quick dialogue; seems easier than I thought! When you say not to run near other wires, is it because of the hot load running through to/from? Maybe extra insulation?

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Re: RE: Ammeter Wiring, 12V

#4

Post by awander » Mon Jun 11, 2012 1:19 am

I agree with the ammeter placement(in the negative lead from battery to ground) but I to am stumped by the advice not to run it near any other wires...

You could also run the ammeter in the positive lead to the battery(as I did on my '52 FL), but then you need to run 2 wires (a send and a return) from the ammeter location to the battery location.

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Re: RE: Ammeter Wiring, 12V

#5

Post by cdndewey » Mon Jun 11, 2012 1:48 am

I'd recommend running a voltmeter instead. An ammeter must be inline for the current to run through it. If one of the wires break or comes lose you have a live wire with full current ready to short against something and fry who knows what. With a voltmeter you are measuring potential difference across two terminals and no hot wire should either of them separate.

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Re: RE: Ammeter Wiring, 12V

#6

Post by BlainesGarage » Mon Jun 11, 2012 1:51 am

Chobber,
i just suggested keeping it away
from other wires so they dont rub through
because at that point, you might wish it DID have
a fuse.


Blaine...

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Re: RE: Ammeter Wiring, 12V

#7

Post by awander » Mon Jun 11, 2012 3:28 am

I have both an ammeter and a voltmeter on my '52,and I find it very interesting to see the relationship between the 2 values as I ride.

You will be better off with an ammeter with a 10-0-10 range, if you can find one. the 20-0-20 is not really sensitive enough for a bike(hard to read) The ammeter should never read outside the range of -7 to +5 or so,unless there is a problem.

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Re: RE: Ammeter Wiring, 12V

#8

Post by cdndewey » Mon Jun 11, 2012 3:42 am

awander wrote:I have both an ammeter and a voltmeter on my '52,and I find it very interesting to see the relationship between the 2 values as I ride.

You will be better off with an ammeter with a 10-0-10 range, if you can find one. the 20-0-20 is not really sensitive enough for a bike(hard to read) The ammeter should never read outside the range of -7 to +5 or so,unless there is a problem.

I'll take a voltmeter any day. I understand 12 plus volts a lot better than -7 to +5.

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Re: RE: Ammeter Wiring, 12V

#9

Post by awander » Mon Jun 11, 2012 4:10 am

Yeah, but as i am finding out, your voltage can be "lower" than what we usually think of as charging voltage, but still be pumping current into the battery. And the charge rate can be very low while the voltage is high, as well.

I am going to make some records of what I observe on the '52, 6V with 3-brush, and post them here. i find the figures very interesting.

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Re: RE: Ammeter Wiring, 12V

#10

Post by cdndewey » Mon Jun 11, 2012 5:37 am

awander wrote:Yeah, but as i am finding out, your voltage can be "lower" than what we usually think of as charging voltage, but still be pumping current into the battery. And the charge rate can be very low while the voltage is high, as well.

I am going to make some records of what I observe on the '52, 6V with 3-brush, and post them here. i find the figures very interesting.

I'll be interested to see what you come up with.

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Re: RE: Ammeter Wiring, 12V

#11

Post by BlainesGarage » Mon Jun 11, 2012 2:09 pm

Dewey,
i recommended putting the ammeter in line with the negative wire so if it does short out to the frame or such, nothing happens.
There's no harm if the ground wire would get grounded. To mount the ammeter somewhere you can see it might require several feet of wire, and if you use the hot side of the battery, you have several feet of potential problems.

An ammeter is quite simple. It just indicates which way the current is flowing to and from the battery. positve side of zero, good. negative side of zero, bad.

A voltmeter 'requires' a 'hot' wire run to it and you run the risk of the hot wire shorting to ground if not routed and secured properly.

Awander,
Just curious as to where you have both gauges mounted.

Thanks, Blaine....

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Re: RE: Ammeter Wiring, 12V

#12

Post by awander » Mon Jun 11, 2012 4:59 pm

Hi Blaine:

i have the ammeter(a small analog one) mounted to the handlebar, and the voltmeter(a home-built digital one) right near it, on the windshield bracket.

The ammeter is wired with 2 12AWG conductors coming up between the tanks to/from the battery Plus. I may change that so it breaks the ground instead.

Th voltmeter gets plus and ground from inside the triple tree covers.

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Re: RE: Ammeter Wiring, 12V

#13

Post by FlatHeadSix » Tue Jun 12, 2012 2:55 am

The wiring diagram that Panhead just posted is for the 1940-1946 "cat eye" dash, those had idiot lights and no ammeter. Does anybody have a good digital copy of an early knuckle diagram with an ammeter in the dash?

bottom line is that all the early H-D ammeter equipped bikes had the ammeter on the negative side of the battery. The ammeter was "shunt-wound" which means that all the current, any current, that the bike used passed through the ammeter, it was wired in series.

There have been several comments that suggested that a voltmeter would be more useful, or that a -20-0-+20 ammeter would not be sensative enough. My opinion is that an ammeter is far more useful than a voltmeter and that the -20-0-+20 ammeter is exactly right for a system with a "moderate" load (such as a 12 volt system running spot lights).

So, wire the ammeter on the negative side of the battery so that ANY load used by the bike passes through it. If it reads backwards, just reverse the connections, its that simple. Start the bike, flip on all the lights, if it reads negative amps then your generator isn't producing enough to support the load, its that simple, really!

here is the 1931 wiring diagram, its kind of hard to follow, but it shows that the factory connected them on the negative side of the battery and that any current that flowed through the system went through the ammeter first.
mike

Image

1931 Wiring Diagram W/Ammeter

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Re: RE: Ammeter Wiring, 12V

#14

Post by BlainesGarage » Tue Jun 12, 2012 3:11 am

Mike,
That's perfect!
Just thought i'd add that you wouldn't want to do this to your electra-glide!

Blaine...

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Re: Ammeter Wiring, 12V

#15

Post by Chobber69 » Sun Jun 17, 2012 2:06 am

...couple pics, since I started the topic; gotta keep it simple :-)
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