# Ammeters for individual lanes



## Boosted-Z71 (Nov 26, 2007)

I have a project that I am working on that would be very similar situation to adding an amp meter to an individual lane, Would the shcematic below be the correct connection for the meter? I want to know how many amps the car is drawing. 

Thanks

Boosted


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## Dyno (Jan 26, 2009)

Boosted-Z71 said:


> I have a project that I am working on that would be very similar situation to adding an amp meter to an individual lane, Would the shcematic below be the correct connection for the meter? I want to know how many amps the car is drawing.
> 
> Thanks
> 
> Boosted


If I'm reading that correctly, I believe so. I have put my multi meter inline with the controller on several occasions to read the amps so where you have mounted A should be correct. I was thinking of putting in gauges too and most of them need an external power supply and a shunt. Most of the cheapies I see on the bay are in Hong Kong and most have the wiring diagram in the listing.


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## Boosted-Z71 (Nov 26, 2007)

Yes that is what I am doing and I have 3 meters, Voltage input, output voltage of my slave & and amp meter, all are the small 3-digit digital type. I have both the voltmeters working as they should, the problem is with the amp meter. 

The seller says it does not need a shunt, I know better, and I tried it without a shunt and it will not pass the power, the other problem is the seller cannot tell me what value shunt to use, I have a shunt that I believe to be a 30 amp 75 mv rated and when I connect it up like in the schematic and attach the meter to the small screws I get false readings on the meter, If I connect my DVM in series like the schematic I can read the amp draw just fine, so its either in the meter, or the wrong value shunt for the mini amp meter & I dont know how I can find the correct value shunt for that mini amp meter. 

With these small mini digitals, a seperate power supply is easy, 1 9 volt will power them for many hours, that is what I am doing, cheap & easy. Just make sure you get 3 wire meters, pos, neg & measure. 

Thanks Dyno, I thought I was correct in my thinking, but right now the amp meter is giving me fits.

I had it all working with an analog panel amp meter as well, just saw these nice, small digital meters and thought I would give them a try. 

If you have any ideas on the shunt, let me know.

Boosted


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## warnergt (Feb 9, 2000)

That schematic looks good to me. 

Note that when the driver applies the brakes, the ammeter should go backward 
(probably just a tiny bit and just for an instant but let us know, I'm curious).

I've been meaning to set up a test circuit for my electronic controllers so I 
can test the brakes. How would you know if they didn't work?


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## Dyno (Jan 26, 2009)

Honestly, I've never used one of those gauges before and was just regurgitating information I read in my research for an amp gauge. Maybe you need a shunt that is closer in amp rating to what the cars will be drawing? My multi meter says 10 amp max when reading amps, maybe the 30 amp shunt has too much resistance? Electrical is not my forte. I know just enough to get by.


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## Hornet (Dec 1, 2005)

I figured on kit bashing old multi-meters for their shunts.
Any resistor wire laying around Jeff,it might work?
I think 75 mv is too much resistance.
I wonder if a piece of small guage wire wrapped in a coil might even be enough resistance,something like 22G or higher,you'd have to put several wraps in it 
Just ideas,lol
Rick


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## Boosted-Z71 (Nov 26, 2007)

I should have said I am not using the braking circuit on this setup.

Thanks for all the replies, when I get it figured out I will post back with the results

Boosted


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