# Contator conundrum



## tricklecharge (Oct 8, 2013)

*Contactor conundrum*

Hello all. New to the forums but have read them for years. I'm having some issues with my EV, specifically the main contactor. 

First a little background: I've had my EV (1988 ranger conversion) for about 5 years. Its clutchless with a 72v Alltrax AXE controller, Curtis PB-6 potbox, Kilovac EV200AAANA (with economizer) contactor, GE 11" lift truck drive motor, 36/48v 1750 RPM, 12v auxiliary battery power for lights, etc. I didn't build it myself, as I got a good deal on it and couldn't have bought the parts for what I paid for the whole truck. Overall the truck has been trouble free.

My problem: Last week I was driving and noticed that I was no longer hearing the familiar 'click' of my contactor when I applied/let off of the accelerator. The truck drove fine other than that. When I got home I found the contactor to be stuck (fused?) closed as the controller and motor were still receiving power even though the ignition was off and the key was out. I disconnected the main battery manually and ordered a new contactor (another kilovac EV200AAANA with economizer). 

After installing the new contactor in the exact same configuration as the first (red wire from economizer to PB-6 potbox, black wire from economzier to ground, HV leads properly hooked up to A1 and A2) , it doesn't engage. 

I once again disconnected the main battery, removed the contactor and tested the coil with a 12v battery: The contactor is good, the coil works, it clicks (it makes a distinctly different (normal) sound than the fused contactor). 

I tried to test for voltage coming from the potbox (where the red wire is plugged in) when the accelerator is depressed. The the voltage goes from 0 to only 3 mV and I was expecting to see 12+ VOLTS unless I am mistaken.

So I guess my question is: Am I supposed to see 12+volts coming off the PB-6 plug that goes to the contactor economizer when the accelerator is depressed to activate the contactor? 

There is one other wire plugged into the PB-6 and I have yet to figure out where that one goes. 

Any ideas on how to troubleshoot this problem and get the ol Etruck back on the road?


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## major (Apr 4, 2008)

*Re: Contactor conundrum*



tricklecharge said:


> Hello all. New to the forums but have read them for years. I'm having some issues with my EV, specifically the main contactor.
> 
> First a little background: I've had my EV (1988 ranger conversion) for about 5 years. Its clutchless with a 72v Alltrax AXE controller, Curtis PB-6 potbox, Kilovac EV200AAANA (with economizer) contactor, GE 11" lift truck drive motor, 36/48v 1750 RPM, 12v auxiliary battery power for lights, etc. I didn't build it myself, as I got a good deal on it and couldn't have bought the parts for what I paid for the whole truck. Overall the truck has been trouble free.
> 
> ...


Here is the wiring diagram. It will be easier to help if you verify it is wired this way, or show us how it is different from this. 

http://www.alltraxinc.com/files/Doc100-045-A_DWG-AXE-No-Reverse-wire-dia.pdf


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## tricklecharge (Oct 8, 2013)

Hey Major, 

Thanks for the response, your input on these forums is always welcome and insightful. I am fairly sure that IS the way my EV is wired. My issue is I didn't build the EV and all the wires are contained within black ribbed wire holders hence it makes tracing this stuff difficult. Since it takes a 12v input to activate the contactor and I'm only seeing 3mV at the +wire (red) to the contactor I'm guessing I'm having some sort of issue with the accelerator pedal switch or perhaps the old trucks ignition in the column. 

The PB-6 has three places to plug in a wire on the lower left hand side of the potbox. We'll call them 1 2 3 from left to right. The red wire from the contactor is on 1. 2 is empty. 3 has the mystery wire I haven't been able to trace yet. Its a mystery to me why I see the 3mV when the accelerator is depressed. I would guess I would see no change in voltage if I have a disconnected wire somewhere under the dash. 

If we assume the truck is wired as per the Alltrax diagram, would I typically be seeing 12+V on plug 1 on the PB-6 with the accelerator slightly depressed? 

I'll try and get that other wire on the PB-6 traced tonight.

Thanks,

tricklecharge


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## major (Apr 4, 2008)

tricklecharge said:


> Hey Major,
> 
> Thanks for the response, your input on these forums is always welcome and insightful. I am fairly sure that IS the way my EV is wired. My issue is I didn't build the EV and all the wires are contained within black ribbed wire holders hence it makes tracing this stuff difficult. Since it takes a 12v input to activate the contactor and I'm only seeing 3mV at the +wire (red) to the contactor I'm guessing I'm having some sort of issue with the accelerator pedal switch or perhaps the old trucks ignition in the column.
> 
> ...


Hi trick,

You say you have a 72V battery. If it is wired per the diagram, then 72V is applied to the contactor coil when the microswitch on the PB-6 is closed. The contactor you specified has a coil economizer rated for 36V max. Something doesn't jive. There is also a fuse in the branch running to the microswitch. It is conducting? 

Also, the PB-6 is primarily a variable resistor which typically has a 2-wire cable for hook-up. Secondarily, there is a microswitch activated by the swingarm on the PB-6 which has 3 tabs for spade terminal or faston connections. The 3 tabs are common, NO and NC. It is just a switch. One terminal is powered by the branch circuit and the other (NO or Normally Open) is closed to complete the circuit when the swingarm is moved.

The wiring diagram shows that branch circuit going thru the microswitch then to both the contactor coil and terminal #1 on the Alltrax. Terminal #1 on the Alltrax needs battery positive (+72V). Your contactor needs 12V. The diagram depicts a system where the contactor coil is rated for battery voltage. 

You need to figure out how your truck is wired. 

major


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## tricklecharge (Oct 8, 2013)

I've traced the wire and discovered the problem. It's always the smallest details that get you. The 'mystery wire' leads to a 12v+ wire in the original ICE wiring harness under the hood. This wire receives 12v+ when the accelerator is even slightly depressed. The guy that did the conversion left both the male and female ends of the end section of the wiring harness intact, including some mess of wires that included what almost looked like an AC 2 prong plug (original ford part) wrapped in electrical tape. This seems to have gotten caught in the steering shaft and thus ripped the 12v+ lead out of the harness/tape/plug mess.

The smallest detail of the story in the first post is when I was driving last week I had made a turn during acceleration from a stop and heard a distinct "clunk" (I love how you can hear so much in an EV) while turning the wheel, which also seemed to be abnormally hard to turn. After this I headed to a parking lot and tested the steering and found it to be fine so I drove home. It was less than a mile after this that I noticed the lack of contactor 'click'. Thus I think the clunk was the plug mess hitting the inside fender after the steering tore the wires. Needless to say the wiring mess has been cleaned up and the cables near ANY moving part of the Etruck have been re-routed.

HOWEVER: This raises a NEW question: 

When the (main and only) contactor lost 12v+ it SHOULD have disconnected the high voltage, correct? 

It instead seemed to fuse shut. 

It is to be noted that I am NOT using a precharge resistor (but I've ordered one since, however I want to get a relay to activate it before I install it) OR a diode (because I believe it is unneeded when using a kilovac contact with economizer). Furthermore the contactor was at least 6 years old.

So, I should have I lost HV when the 12v+ wire got pulled out or not?

-tricklecharge


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## major (Apr 4, 2008)

tricklecharge said:


> I've traced the wire and discovered the problem. It's always the smallest details that get you. The 'mystery wire' leads to a 12v+ wire in the original ICE wiring harness under the hood. This wire receives 12v+ when the accelerator is even slightly depressed. The guy that did the conversion left both the male and female ends of the end section of the wiring harness intact, including some mess of wires that included what almost looked like an AC 2 prong plug (original ford part) wrapped in electrical tape. This seems to have gotten caught in the steering shaft and thus ripped the 12v+ lead out of the harness/tape/plug mess.
> 
> The smallest detail of the story in the first post is when I was driving last week I had made a turn during acceleration from a stop and heard a distinct "clunk" (I love how you can hear so much in an EV) while turning the wheel, which also seemed to be abnormally hard to turn. After this I headed to a parking lot and tested the steering and found it to be fine so I drove home. It was less than a mile after this that I noticed the lack of contactor 'click'. Thus I think the clunk was the plug mess hitting the inside fender after the steering tore the wires. Needless to say the wiring mess has been cleaned up and the cables near ANY moving part of the Etruck have been re-routed.
> 
> ...


Contactors weld due to arcing across the contacts. This occurs when breaking current which is opening (de-energizing) under load, or closing (energizing) into a capacitance (hence the need for precharge). Loosing the 12V to the coil (thru the economizer) de-energized or opened the contactor under load (while conducting current). This causes an arc. The Kilovac is designed to be capable to handle this situation and in fact can open under thousands of amperes at least once and break the circuit safely. So I suspect what happened is that when the 12V wire separated, it arced and broke and remade the coil circuit causing the main contacts to open and close causing the weld to occur. Just a theory. Maybe the Kilovac was in bad shape from not having the precharge and the prior use.

You need to have the proper precharge or you risk damage to the contactor. Also, I am not a fan of having the contactor wired to the microswitch such that it opens each time you let up off the throttle pedal. It is unnecessary IMO. I would keep the contactor engaged until you turn off the key switch. Use the microswitch for the pin#1 which will disable the Alltrax when the throttle is released.


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## evnz (Jul 24, 2010)

Major 
I have the ev-200 contactor feeding a sol 1 do i still need a pre charge ?
thanks 
owen


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## major (Apr 4, 2008)

evnz said:


> Major
> I have the ev-200 contactor feeding a sol 1 do i still need a pre charge ?
> thanks
> owen


Soliton controllers have internal contactors and precharge. External precharge is not required for the controller. But as always, RTFM; I mean you should check the manual to be sure


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## dougingraham (Jul 26, 2011)

evnz said:


> I have the ev-200 contactor feeding a sol 1 do i still need a pre charge ?


The Soliton 1 doesn't need precharge. It handles that itself. The Soliton does need pack voltage across the input before it wakes up or it will error with no pack voltage and then won't wake up. However there are other things in your car that might need precharge. Like the charger or the DC-DC converter. These devices might be able to take care of themselves but using a contactor to switch pack voltage to them could allow high currents to briefly flow through the contactor and cause it to eventually fail.


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