# Is my shunt wired correctly?



## jlsawell (Apr 4, 2008)

This would have come in handy before I started this thread...



Hey - look over there!!!

<leaves quickly>


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## O'Zeeke (Mar 9, 2008)

jlsawell said:


> This would have come in handy before I started this thread...
> 
> 
> 
> ...


Where?? I didnt see nothing! Thanks for posting this Justin, I just wired mine up and figured i had a 50-50 chance of wiring the ammeter right and of course it wasnt right so thanks again


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## jlsawell (Apr 4, 2008)

O'Zeeke said:


> I just wired mine up and figured i had a 50-50 chance of wiring the ammeter right


Heh. As an accountant, I find those odds to be poor. Hence my almost psychotic need to re-check everything, plus we're dealing with electricity so I'm doubly careful...

Glad I could be of assistance and someone can learn from my mistakes...


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## jlsawell (Apr 4, 2008)

Hang on a minute!!

Looking closer at this diagram, it looks like the volemeter should be connected directly to the pack voltage.

Does that mean there's 144v coming in through those 2 little wires?

I see the units are powered by the VB1212S-1W, but I connected all 4 wires up to my 12v 12ah battery and was surprised by the result.

The Ammeter displayed 140A and the voltmeter displayed 1.00 volts.

Can someone who'se done this before (Kiwiev, your display looks similar) explain how they wired the system up to their pack, and what the typical readouts are in terms of volts/amps?

I would have thought there was 12V in the "pack" and 0A drawn since they're only digital readouts...

any idea as to why there's such a discrepancy? Let me know if you want pics and I'll photograph the hookup.


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## Qer (May 7, 2008)

jlsawell said:


> The Ammeter displayed 140A and the voltmeter displayed 1.00 volts.


Hm? My guess would be that you've mixed up the wires from the ampere meter and the volt meter. You're SURE you've wired it exactly as in the diagram?


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## e_canuck (May 8, 2008)

jlsawell said:


> Hang on a minute!!
> 
> Looking closer at this diagram, it looks like the volemeter should be connected directly to the pack voltage.
> 
> ...



Hi jlsawell.

I think your are right about what you should see. Something isn't right.
But then, what do I know, my ammeter is busted. Maybe I did that.

You are correct. The two wires bring pack voltage to the cabin.

Automotive wires often say "low tension", "low voltage" or "nothing" on the package/spool. Get something rated for higher voltage and mark them well so you don't use those for your new satelite radio.

Iam including a scan of a package of wirring I got recently.











It looks just like regular wirring. Read the package well. The amperage will be low, so the gauge can be small. The voltage high, so well insulated.

Take care,

DP


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## Xringer (Oct 12, 2008)

I am an electronics tech, but not an EV guy (yet).

The labels on the shunt pic look a little odd to me.
Like maybe you would blast in half.?.

It's a resistor. It will go in *series *with one of your main wires between
the battery and load. 
Lets say you cut the thick Black *OR* Red cable from the battery,
and re-connect it to the big nuts on either end of the Shunt.
Not both on the same end.

When current flows thru the resistor elements (the thin wires in the center of the shunt), a low voltage will develop across them. Hook your meter to
the two small screws.. 
*DO NOT* let either of your meter wires come in contact with any metal 
or wiring in the EV. That meter must be *floating above ground.
*It should also be self powered. And NOT powered by voltage coming
from any part of the main batteries (unless isolated with a DC-to-DC converter).

Of course, I may be looking at the picture and not seeing something critical.


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## jlsawell (Apr 4, 2008)

Xringer said:


> I
> The labels on the shunt pic look a little odd to me.


Thanks Xringer - I realised the pic was wrong when i posted the schematic that follows it.

Qer, I'll post a pic when I get home tonight. I'm pretty sure I've got them right, because the Voltmeter would have a tiny "V" on the display and the Ammeter would have a tiny "A" on the display, no?

e_canuck, your wire has 25 PIES - does Lexus know about that???


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## Xringer (Oct 12, 2008)

jlsawell said:


> Thanks Xringer - I realised the pic was wrong when i posted the schematic that follows it.
> 
> Qer, I'll post a pic when I get home tonight. I'm pretty sure I've got them right, because the Voltmeter would have a tiny "V" on the display and the Ammeter would have a tiny "A" on the display, no?
> 
> e_canuck, your wire has 25 PIES - does Lexus know about that???


Your Volt meter should work fine directly connected to the pack.

Your Amp meter isn't really a true amp meter. It's actually just another
volt meter with a face marked in Amps.
It's just measuring the voltage across the shunt resistor to find out
how much current is flowing thur it.. 


You can actually just forget the shunt and use the wire for a shunt.
Here's a neat calculator showing how much loss you get with 
different sized wires.
http://www.nooutage.com/vdrop.htm


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## Guest (Oct 17, 2008)

You have a funky looking shunt. I have one that looks like that also but only one set of large bolts. Not sure why yours has two sets. Anyway I have my amp shunts set up different now but started like the diagram posted below. I now have them hooked up where I only have one amp meter for both my battery and motor with a switch to change from one to another. I have two shunts set up where one is set for motor amps and the other for battery pack. Two sets of wires coming to the switch and one set of wires coming to the amp meter. Works real well. For starters here is my original set up. Take your battery + and put your shunt in line with that between your battery pack and main contactor. Then take your small wires and run them to your meter.




jlsawell said:


> Got a load of parts from ZEVA this week. It means I can take the next step with the control circuit and wire somethings together and have a learn/play/make youtube video/etc...
> 
> So: my first challenge is: how does the shunt/ammeter/voltmeter wire up? KiwiEV's pics have been very educational so far but he's playing a little close to the chest with the control box wiring pics...
> 
> ...


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## Xringer (Oct 12, 2008)

Now that's a clear diagram! 

I would be very careful to make sure there was no chance of anything or anyone touching the back of that meter. 

If other side of the battery pack is at chassis ground, putting your fingers on those meter wires could kill you. 

Unless you use a fuse in both meter lines, I would make real sure the meter cable was routed in such a way to protect the insulation from any damage. No sense melting copper under the dash board.


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## Guest (Oct 17, 2008)

Gauge is mounted in dash. Main pack is isolated. Dooh! Why would you think different. It is just a plain and simple diagram. It's up to you where you mount your own stuff in your own EV. Nothing complex and it works.

Pete : )






Xringer said:


> Now that's a clear diagram!
> 
> I would be very careful to make sure there was no chance of anything or anyone touching the back of that meter.
> 
> ...


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## Xringer (Oct 12, 2008)

gottdi said:


> Gauge is mounted in dash. Main pack is isolated. Dooh! Why would you think different. It is just a plain and simple diagram. It's up to you where you mount your own stuff in your own EV. Nothing complex and it works.
> 
> Pete : )


That's great Pete. But Justin is an Accountant. 
He might not be up to speed on this electrical stuff like you are. 
If he was, he would not be posting questions here..

And, I could have saved some time posting obvious safety info..
I'll just go to bed now. I'll be wiring up some Laser hardware at the lab
real early in the morning. When you get old, you need your rest.


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## Guest (Oct 17, 2008)

Well he's got to do some homework himself. Heck, I'm just an X-Ray Tech. 

Of course there must be safety involved because there is such high voltage involved. I am doing loads of homework still. As I learn more I upgrade my EV. Still I am not at a point where I drive mine daily. I love my EV and I love learning about it and making it work. Just gotta do it. But safely. 


Pete : )






Xringer said:


> That's great Pete. But Justin is an Accountant.
> He might not be up to speed on this electrical stuff like you are.
> If he was, he would not be posting questions here..
> 
> ...


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