# Intermittant Loss of Power while driving



## djsammy (Sep 15, 2009)

Car: 1999 Jetta
Batteries: 12, 12 Volt Trojan T:1275
Motor: Netgear Warp 9
Charger: Quickcharge 144V
Controller: Kelly
Potbox: FourthGen with microswitch (Same as Curtis PB6 Pot Box)(http://www.fourthgen.net/potentiometercart.shtml 

Meters: Voltmeter, Ampmeter in line
Battery Meteraktraker at battery pack


Situation:
All batteries are at full charge. 
Paktrakr 154V
Aux Batteries at 12.7V


When I turn the key on.....
Voltmeter quickly to 154V
lightly press accelerator -->car moves fine. Travel roads without problem. 
Then lightly press accelerator---> voltmeter QUICKLY pins to less than zero, NO POWER
Pull over, wait seconds, voltmeter goes back to 154---> press accelerator ,, works fine...

this repeats itself at unpredictable intervals...

Paktrakr voltage is always maintained

When it happens the voltmeter QUICKLY pins to less than zero. When I turn off the battery cutoff switch, the voltmeter SLOWLY goes down to zero. Additionally, when the inertia switch is activated to off, the voltmeter SLOWLY goes down to zero. I am hoping this is a clue as to what is the problem. I don't know how to evaluate the issue as it is intermittant when driving. I was able to look at the error LEDs of the Controller when it happened once (backing up), and the controller error is "low voltage". This is the same error as when the battery cutoff switch (the big red button) is off. So I don't think the problem is internal to the controller. I am suspicious that it is in the potbox somehow.

Thanks for the help. 


DJS


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## DavidDymaxion (Dec 1, 2008)

It sounds like something is suddenly getting disconnected. Have you run down the pack with a voltmeter when it happens? Wiggled all the connections?


djsammy said:


> Car: 1999 Jetta
> Batteries: 12, 12 Volt Trojan T:1275
> Motor: Netgear Warp 9
> Charger: Quickcharge 144V
> ...


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## djsammy (Sep 15, 2009)

The problem is that it corrects itself so quickly that I can't 'run down the pack' with a voltmeter. That's why I was hoping that the voltmeter pinning so quickly to negative (?reverse polarity?) may be a clue.
djs


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## dimitri (May 16, 2008)

Where exactly is your voltmeter connected? Sounds like its after the main contactor, maybe at controller's B+ and B- ?

When this problem occurs, do you hear contactor clicking on/off ? What type of contactor is it and do you have 2 of them or just one? Is high pedal microswitch at the potbox used? If so, how is it connected?

Can you connect ohmmeter to potbox while in the garage and measure resistance while slowly moving the arm? Does it change smoothly or jerky?

How did you connect 2 wire potbox to 3 wire input on Kelly? Did you use pull up resistor?

Do you have precharge resistor? What value and where is it connected?


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## Stunt Driver (May 14, 2009)

if you'll post a wire diagram it may be possible to guess where is the disconnect. With out it - unlikely.


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## edsammy (Jun 15, 2009)

here is a basic wiring diagram of the car. MC2 is engaged by a relay which is connected to the pot box micro switch and also send a signal to the controller through J2. i am not 100% sure on the rating of the precharge resistor but i will check it tomorrow. hope this information will help. let me know if you need more details


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## Guest (Oct 9, 2009)

It is possible that the contactor is to blame. I had a bad one. It is also possible that the pot is to blame. Had that issue too. Could be that the parameters are not set properly for your setup and it is cutting out when the controller detects a parameter that is out of whack.

Pete


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## edsammy (Jun 15, 2009)

here is a more detailed diagram and the pinouts for the j2 connector on the kelly controller. the connector pinouts show a 1k pullup resistor connected from 5v out to throttle in. the wiring was done by a third party so the full extent of the configuration is not entirely known yet. i do not have the serial cable for the kelly controller but i will look into buying one to try and edit some setting to fit our specifications. thanks again


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## Guest (Oct 9, 2009)

What is the 1k resistor between 4 and 5? Interesting. I will have to take another look the diagrams from Kelly. You using a PB-6? Kilovac contactor? 12 volt coil power? DC DC? What kind? What output? 

Pete


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## neanderthal (Jul 24, 2008)

This is probably not what is going on, but the same thing happened to me. It turned out to be my ignition key switch. Turning the key again and wiggling fixed it, until I repaired the switch.


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## Dave Koller (Nov 15, 2008)

Could even be as simple as a loose wire to the contactor - (coil side)...

Less than zero is a bit of a puzzle!


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## Amberwolf (May 29, 2009)

I would bet that the "negative" voltage reading is the collapse of a field in a coil, but I'm not sure which one that would be. If it were in your motor, the controller should be dealing with that and it shouldn't be a *negative* voltage, AFAIK. If it were a contactor coil, or something like that, perhaps it would cause a negative voltage spike.

The thing is, that shouldn't be much of a voltage at all, certainly not enough to cancel out *more* than your pack voltage. 

Since your diagram doesn't (AFAICS) show where the meter is hooked in, I'm not sure where it would come from.
________
Marijuana dispensaries in


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## djsammy (Sep 15, 2009)

Thank you for all the replies. Dimitri, Amberwolf, Dave, Stunt, Gottdi, Neand.. answers to some of the questions....


Voltmeter is connected at controller B+ B-
There are 2 contactors in series (Albright SW)200
I do NOT hear the contactor click when the problem occurs.
I pedal microswitch at the potbox is used. I need to find out where it is wired.
I will do the ohmeter measurements this weekend.
There is a pull up resistor.
There is a precharge resistor on the second contactor.

djs


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## Amberwolf (May 29, 2009)

Well, I still am not sure what could cause the negative voltage spike that pushes the meter *below* zero. 

As for the meter *quickly* going to zero, the only thing that would do that given your wiring *is* a negative voltage spike, because if the connection to the batteries were lost, the controller caps discharge/motor spindown would slowly go to zero, and if the connection to the controller were lost then the meter would actually go *up* in voltage as the pack recovered from load sag. 

If the meter itself were being disconnected, it would drop to zero instantly, but that wouldn't affect your power to the motor/etc.


Are all the ground returns from motor to controller, and controller to pack, all ok?
________
LIVE SEX WEBSHOWS


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## BradQuick (May 10, 2008)

I can't explain the negative voltage reading, but I noticed that my kelly would drop out briefly sometimes when I clicked the high beams on. My DC-DC converter wasn't holding the output steady. I put in a huge capacitor and the problem went away. What are you powering the 12V system with?

- Brad


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## djsammy (Sep 15, 2009)

The 12V system is powered by a seperate two Trojan T-1275s seperate from the main pack. By the way Brad how has the netgain charger been working out for you?
DJS


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## BradQuick (May 10, 2008)

I've been very happy with the netgain charger. It's stupid simple. When at home, I plug it into 220V. When at work, 110V. There aren't a lot of bells and whistles, but the blinking LED gives me all of the feedback I really need. I like that I just plug it in and walk away.

- Brad


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## edsammy (Jun 15, 2009)

could this problem be cause by something like this or this?
when the car is off i measure a negative voltage between the frame and the B+. It seems like this could cause our problem


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## djsammy (Sep 15, 2009)

Upon more measurements today I found out there is a 70V reading from the Kelly Controller case and the car chasis. There must be a shorted wire inside the casing to cause this , no? I know there are plenty of threads with problems with the Kelly. Has anyone heard of this one? I am going to email Kelly now that I have found a real problem.
djs


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## TheSGC (Nov 15, 2007)

djsammy said:


> Upon more measurements today I found out there is a 70V reading from the Kelly Controller case and the car chasis. There must be a shorted wire inside the casing to cause this , no? I know there are plenty of threads with problems with the Kelly. Has anyone heard of this one? I am going to email Kelly now that I have found a real problem.
> djs


It sounds like your controller kicked the bucket. I know some older Kelly's have their B- tied into their casing (mine is, what a pain). Kelly should replace the controller under warranty.


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## Guest (Oct 14, 2009)

Excellent! Glad you found a real problem. Kelly should fix it for you under warranty. They actually are good about that. You really should have good power to your motor. That is a big power drain. Could be your problem. Sounds like you finally found it. Persistence pays off.

Pete


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## djsammy (Sep 15, 2009)

SGC 
On the older Kelly's with the B- grounded (like yours), do you get a voltage reading from the controller casing to ground?
DJS


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## TheSGC (Nov 15, 2007)

djsammy said:


> SGC
> On the older Kelly's with the B- grounded (like yours), do you get a voltage reading from the controller casing to ground?
> DJS


I have not tested that. I do know that my car chassis GND and controller GND are the same and I can get shocked when charging my EV if I forget to unplug the main B- GND plug and flip my breaker off. 

If you are getting a voltage reading between the casing and your chassis ground, then there is either a short in the controller, or somewhere in your main wiring setup. I'll check mine to be sure, but I don't think I have any voltage readings except for 0v from the controller case to car chassis.


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## djsammy (Sep 15, 2009)

I spoke with Steve from Kelly today and he does not think the -70V reading from the case to chasis is a short. In fact, somehow our main pack is 'grounded'. I am measuring the full -153V from the B+ at the controller to the chasis. So the fact that the case is showing -70V is from the resistance internally. He thinks my system is grounded at the shunt with the ammeter, but I am using an analog ammeter so there should not be a ground there. I know there was another thread talking about this ground problem
(http://www.diyelectriccar.com/forums/showthread.php?t=34503) (as pointed out by my son earlier on this thread), and I will investigate the source of the ground. My question now is, could this grounding problem be a source of my intermittant loss of power issue?
Somehow during the drive the negative voltage cancels out the battery voltage? Sounds like a stretch but... 
djs


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## djsammy (Sep 15, 2009)

Problem solved!!

We were able to voltage test the problem with clamps on a voltmeter that we moved thru different parts of the circuit while driving back and forth in the driveway. I was able to get the fault to happen in my driveway. The microswitch on the potbox did not send 12V to the relay when the loss of power occurred. So we ordered a new microswitch. While we waited for the switch to arrive, my son Eddie (edsammy) saw that there was no diode across the relay. He felt that the relay must have a diode. So he fashioned a diode across that relay and VOILA, problem solved. I have been driving now for two weeks with no episodes of loss of power. The drive is much smoother now when I change from coasting to using the throttle. Very exciting. Explanation? I guess the back EMF would intermitantly cause the microswitch to fail? Anyone?


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