# Wire diagram help



## Voltswagen (Nov 13, 2008)

Travdude
I'd like to see a 1000ohm resistor across the two poles of your contactor.
This keeps the current from slamming into your controller everytime you turn on the key. It bleeds a very small amount of current into the controller to keep it topped up.

My DC/DC converter is hooked up full time. There should be no problem unless you have a ground drain in your 12v system somewhere.

Also I would go through with a small piece of emery paper and clean all the original male spade connections on the Bug and the 2 headlight screw grounds in the trunk. I've fully restored 4 of these and those old connections are bare and get badly corroded.

Roy


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## Travdude (May 11, 2009)

So, the Zilla has a "snubber diode" that they say to put across the contactor coil. Should I put a 1K resistor there too?

Cool, I am glad you are not having problems with your DC/DC connected, I will do it that way.

I will be replacing the stock wire harness, there were some electrical problems before I started the conversion. It is going to be my daily driver, so it has to be dependable.

Do you think the shunts will work just as good on the negative side? They should, I'm just used to putting them on the positive.

Thanks for taking the time to look at my diagram Roy.


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## Voltswagen (Nov 13, 2008)

Travdude
Yes, I would install the Snubber Diode as I understand it dissapates any reverse voltage spike when the ignition is turned off.
As for the 1000ohm resistor, check with Zilla. Their controller may have the resistor already built in so no sense duplicating it if thats the case. Kelly and Curtis controllers don't and must have this added for protection.
Hopefully someone here who owns the Zilla will respond with additional suggestions.

Also, replacing the existing wiring harness is a good idea. Beetles are famous for grounds and voltage leaks.
I replaced the harness on the last two I restored and was never sorry I did. It's tedious but worth the time.
Roy


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## 300zxev (Dec 5, 2008)

Hi 

I'm in the process of installing a 1K Zilla ... and there is no need for a resistor as the Zilla has an internal precharge circuit.

I have a question about the diode though ... is says to connect accreoss the contactors coil ...

The coil is the 12V side right ? ... not the HV ?


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## Voltswagen (Nov 13, 2008)

Yes, the coil is the low voltage or 12v side. Be sure to wire the diode in the correct direction. It should be marked.


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## 300zxev (Dec 5, 2008)

Hi Voltswagen

Thanks for confirming ...

The diode we have is actually supplied with the Zilla and was marked as no polarity and can be hooked up either way.

thanks again


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## Travdude (May 11, 2009)

On the contactor, does polarity matter?

I have a Kilovac EV200 contactor, and there is a + and - on there. Not sure which way it goes.


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## Voltswagen (Nov 13, 2008)

On my contactor I wired the positive side to the positive side of my battery pack thru the shunt. The negative side I wired to the A2 terminal on my motor.
The pic was taken before I installed a 1000ohm resistor across the contactor terminals.

If you magnify the photo you can see the polarity marks in yellow.
So does polarity matter? I could be wrong but if polarity didn't matter I don't think they would go to all that trouble to indicate positive and negative. It adds to cost right?

Now you guys got me thinking I should wire in a diode to protect the coil from voltage spike.
Gheeze Louise! This stuff never ends!


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## major (Apr 4, 2008)

Travdude said:


> On the contactor, does polarity matter?
> 
> I have a Kilovac EV200 contactor, and there is a + and - on there. Not sure which way it goes.


Hi Guys,

Some contactors have a magnetic blowout inside to squelch the arc if they open under load. These contactors are marked with polarity ( + & -) on the terminals. The + needs to be connected to the + of the battery.

Ones like the Kilovac have a very large one time interrupt rating, like 2000A or such. This can only be achieved if the polarity is correct. In normal operation where the contactor is never opened under load, it probably does not matter. But in an emergency if you need to open it under very high current and have it wired backasswards, it could weld up on you 

Regards,

major


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## Voltswagen (Nov 13, 2008)

Major
So the emergency might be a runaway controller right?
And if wired backwards, the contactor, would weld itself when you try to shut off the key.

For that alone....I'm goin with....it matters! 
Roy


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## major (Apr 4, 2008)

Voltswagen said:


> Major
> So the emergency might be a runaway controller right?
> And if wired backwards it would weld itself when you try to shut off the key.


Yeah, controllers have been known to fail shorted, meaning full on. So if you got full voltage and no current limit and both feet hard on the brake, there will be very high current thru that contactor. Fuses can take a little while to blow. You might want to hit the kill switch before the wall. I can't say for sure it would weld if backwards, but Kilovac doesn't stamp the + & - there for no reason


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## illuminateddan (Dec 19, 2009)

Diode across the 12v coil is wired in reverse to the current flow, i.e. white line at the top of the diode connects to the positive. The diode lets the voltage spike generated by the 12v coils emf collapse be routed safely away and prevents damage to anything up or down the line.

Also, quick question, why are you putting the shunts on the negative side?

I'm also converting a beetle, so I'd be interested to hear how you're going!

Keep dubbin....


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## Travdude (May 11, 2009)

Thanks Roy and Major, I will flip it around. I had it wired in series.

Glad I asked, this forum is great.


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## major (Apr 4, 2008)

illuminateddan said:


> Also, quick question, why are you putting the shunts on the negative side?


Hi again guys,

For the ammeter alone, it does not matter where in the circuit you place the shunt. But in the old days, we used these kilowatthour meters which required the shunts be on the negative side else the meter fried. So ever since, I always put the battery current shunt on the negative. I usually use the negative sense lead off the shunt for the voltmeter connection also.

If you are using any type of instruments besides just an ammeter, check the instructions 

major


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## Travdude (May 11, 2009)

illuminateddan said:


> Diode across the 12v coil is wired in reverse to the current flow, i.e. white line at the top of the diode connects to the positive. The diode lets the voltage spike generated by the 12v coils emf collapse be routed safely away and prevents damage to anything up or down the line.
> 
> Also, quick question, why are you putting the shunts on the negative side?
> 
> ...


About the shunts, when I was in the planning stage, I read that it might be safer to put the shunts on the negative side. I think the reason why was because the sensor wires that connect to the shunt would not have the full pack voltage on them. 

I don't think it matters because the pack is isolated from the car anyways.

Then, when I mocked everything up in the motor compartment, things fit better if I put the shunts on the negative side. So, I went with it.


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## illuminateddan (Dec 19, 2009)

Nice,

I'm doing a similar setup to you but with 38 cells (LiFePo4), a ADC L91-4003 motor and an unknown controller (still deciding). Having the shunt on the -ive side would make life so much easier as the front pack will have the -ive terminal.
Quick question, you are measuring battery current and motor current, is the battery current going to be equal to the motor current + dc/dc converter, and if so why not put the battery current shunt on the dc dc converter instead to reduce the traction pack resistance but give you the same data?


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## major (Apr 4, 2008)

illuminateddan said:


> Quick question, you are measuring battery current and motor current, is the battery current going to be equal to the motor current + dc/dc converter, and if so why not put the battery current shunt on the dc dc converter instead to reduce the traction pack resistance but give you the same data?


Hi illum,

I know the question is directed at Roy, but I looked back at his diagram and noticed that he is not including the pack current going to the DC/DC in his placement of the battery current shunt. Maybe he doesn't care, but I would have the shunt placed so it reads total battery current.

Shunts have very low resistance. Like 0.0001 ohm. The shunt needs to be part of the series circuit and carry all the current you seek to measure. And it is wise to display both battery and motor current as most times they will be quite different. You want to minimize battery current to maximize range. You need to monitor motor current so you don't damage the motor. You will find that you can travel at the same vehicle speed in several different gears all having about the same battery current. But the higher gear will have higher motor current. This is particularly important when you encounter hills and need to down shift to keep motor current reasonable. Or when traveling at low vehicle speed in too high a gear.

Regards,

major


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## illuminateddan (Dec 19, 2009)

Hi Major,

So... how much difference will I see between pack current and motor current? Will the pack current not be the same as the motor current with a subtraction for system inefficiencies and controller+dc/dc power costs?

I do like the idea of more meters on the dash thought...


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## Voltswagen (Nov 13, 2008)

Major & Illumin.......
Actually the schematic is Travdude's. Mine is the picture. I only installed one shunt in the positive line between my battery and contactor from which I read both battery current and pack voltage. I don't read motor current tho according to Major I should.
I have recently purchased a Link 10 with a prescaler to replace my Simpson voltage & amp meter. Not sure if their meter is capable of reading motor current or not. I'll have to dig out their manual.

I purchased some of my system from Wilderness EV. They have been converting Beetles since the 70's so I figgered they would know what they are doing. I used their schematic to position my shunt on the positive side. 

Interesting that Travdude's schematic shows a uni-directional diode on his coil with the flow from positive to negative while 300exzv says his diode is
not marked for polarity and therefore must be bi-directional.

BTW, I have no diode on my coil after 1500 miles. Guess I should install one huh?
Roy


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## Gavin1977 (Sep 2, 2008)

illuminateddan said:


> Hi Major,
> 
> So... how much difference will I see between pack current and motor current? Will the pack current not be the same as the motor current with a subtraction for system inefficiencies and controller+dc/dc power costs?
> 
> I do like the idea of more meters on the dash thought...


No because your motor controller is rapidly switching the current on and off to match the required motor current. At low speeds your voltage across the motor might be say 50v and your motor is drawing say 500 amps. That gives a power of 50 * 500 = 25,000W going to your motor from the controller. If we ignore inefficiencies so power in = power out, then your batteries must be supplying 25,000W of power to your motor controller. If your pack is say 150V, that gives a pack current = 25,000 / 150V = 167A.

Dont have an EV yet, so cant give you real world numbers, but hope the above makes some sense.


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## major (Apr 4, 2008)

illuminateddan said:


> So... how much difference will I see between pack current and motor current? Will the pack current not be the same as the motor current with a subtraction for system inefficiencies and controller+dc/dc power costs?


Hi illum,

When you use a PWM motor controller, the motor current can be many times the magnitude of the battery current. In fact, the motor current will always be greater than battery current except when the controller is at 100% PWM (full voltage to motor) or at 0% (no voltage to motor), in which cases the motor and battery current are equal.

This neglects the current to the DC/DC.

Regards,

major


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## Travdude (May 11, 2009)

major said:


> Hi illum,
> 
> I know the question is directed at Roy, but I looked back at his diagram and noticed that he is not including the pack current going to the DC/DC in his placement of the battery current shunt. Maybe he doesn't care, but I would have the shunt placed so it reads total battery current.major


Ah, total battery current is better, I have revised the dc/dc connection.




Voltswagen said:


> Interesting that Travdude's schematic shows a uni-directional diode on his coil with the flow from positive to negative while 300exzv says his diode is
> not marked for polarity and therefore must be bi-directional.
> 
> BTW, I have no diode on my coil after 1500 miles. Guess I should install one huh?
> Roy


Roy, I think the diode in my diagram was backwards, I have revised it. Good eye!

Thanks for your advise guys, I will keep updating the diagram in case someone wants to use it.


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## Voltswagen (Nov 13, 2008)

Travdude
Check that diode before installing. If it has a stripe on it.....the stripe goes toward the negative connection. If it has no stripe it should be bi-directional..........which is idiot proof.  Polarity doesn't matter.
Roy


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## Thaniel (May 25, 2008)

In looking I noticed that it does not show additional fuses for the 12v power coming into the hair ball. I believe the hairball wiring diagram shows 2 four amp fuses. One for SLI + and one for all else. On your diagram I couldn't tell for sure but looks like you have the SLI + switched? Hairball instructions have it going unswitched directly to the battery.

Oh the connections from the killovac contactor to the zilla don't seem intuitive. I believe in the FAQ for the zilla it describes which way to connect it. Took me a few readings to get it right (at least I think I have it). Since it is basically just a switch I had a hard time deciding which side of the wire was + and - 

My observations anyway.

Thaniel


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## EV-propulsion.com (Jun 1, 2009)

Going back to the original diagram, you may want to add an inertia switch to the controller wiring and/or main contactor, in case of collision the low voltage to the controller and high voltage/current after the contactor will be opened.
Most vehicles have them today, to shut off the fuel pump in a collision. The Ford version is the easiest to retrofit to an EV conversion.
Mike
www.EV-propulsion.com


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## Travdude (May 11, 2009)

Thaniel said:


> In looking I noticed that it does not show additional fuses for the 12v power coming into the hair ball. I believe the hairball wiring diagram shows 2 four amp fuses. One for SLI + and one for all else. On your diagram I couldn't tell for sure but looks like you have the SLI + switched? Hairball instructions have it going unswitched directly to the battery.
> 
> Oh the connections from the killovac contactor to the zilla don't seem intuitive. I believe in the FAQ for the zilla it describes which way to connect it. Took me a few readings to get it right (at least I think I have it). Since it is basically just a switch I had a hard time deciding which side of the wire was + and -
> 
> ...


Oh, it was in the Zilla FAQ:

2) In order to increase the voltage handling capability, the contactor power terminals should be wired in series. *The polarity of the contactor should be observed (if the unit uses magnetic blowouts) with one positive terminal being connected to the battery pack positive.* The negative terminal on the other contactor should be connected to the controller B+ terminal. The remaining two contactor power terminals should be connected together + to -. Having the correct polarity on the contactor insures that the arc from a fault current gets blown outward away from the contactor rather than into the center of the contactor mechanism.

You are right about the SLI +, it was wrong on the diagram, I revised it.

Thanks!


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## Dave Koller (Nov 15, 2008)

Voltswagen said:


> Travdude
> Check that diode before installing. If it has a stripe on it.....the stripe goes toward the negative connection. If it has no stripe it should be bi-directional..........which is idiot proof.  Polarity doesn't matter.
> Roy


Roy,
Wouldn't the stripe be the cathode and to *back bias*
the band goes to the positive.. + ---|<---- -


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## Voltswagen (Nov 13, 2008)

Oops my bad. You're right............stripe to the cathode.

His are probably bi-directional. They engineer them now so guys like me can't blow things up.


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