# Controller failure - Full power output on traffic



## DIYguy (Sep 18, 2008)

You need an emergency stop button or device. This can exist in various forms. Some controllers, like EVnetics, have contactors built in that you can build a circuit to. For those without, I would use one or more Tyco contactors (depending on ampacity) to break battery circuit. You can also use a physical breaker with remote shunt trip or cable trip. Finally, what is referred to as an "OH Shieeeeetzzzze" bar. . . if u don't mind running battery current through the cabin space.


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## dladd (Jun 1, 2011)

Even with a manual pull cable or contactor disconnect button, in the scenario of something going full on just off the line while in traffic... well, you will hit the car in front of you before you can pull anything. Not much you can do about that I think.


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## Batterypoweredtoad (Feb 5, 2008)

Is it even slightly likely to fail full on while under very little load?


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## Ziggythewiz (May 16, 2010)

dladd said:


> well, you will hit the car in front of you before you can pull anything. Not much you can do about that I think.


You can not tailgate the person in front of you. 1m is too close no matter the speed. You'll still probably hit them, but if you're at a safer distance the combination of hitting the brakes and the panic button should lessen the impact considerably.


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## somanywelps (Jan 25, 2012)

As unlikely as this is, if you're hard on the brake, your front wheels should be able to brake against the rear wheels, which should be performing a burnout.

Press clutch.

FWD cars you are screwed...


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## rwaudio (May 22, 2008)

I purposely did some burnouts in my 944 and it's not hard to hold the car stationary even if you're burning rubber. I would hope that hitting the brakes would be instinct in this situation and if you have decent reaction time you could stop the car in time assuming you have power brakes. In the time frames involved instinct would likely not make you hit an emergency disconnect lever/button in time to do anything, but as you sit there in traffic doing a burnout you have time to kill it calmly.

You could simulate this in a safe place by simply flooring it and hit the brakes with the throttle on full, if your controller doesn't have a built in safety that cuts the throttle when the brake is pressed you have your answer. I personally know that my brakes can hold the car stationary in 2nd and 3rd, in 1st it creeps forward very slowly as the brakes can't quite hold the torque but with the front wheels locked there isn't much movement.


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## Caps18 (Jun 8, 2008)

rwaudio said:


> I purposely did some burnouts in my 944 and it's not hard to hold the car stationary even if you're burning rubber. I would hope that hitting the brakes would be instinct in this situation and if you have decent reaction time you could stop the car in time assuming you have power brakes. In the time frames involved instinct would likely not make you hit an emergency disconnect lever/button in time to do anything, but as you sit there in traffic doing a burnout you have time to kill it calmly.
> 
> You could simulate this in a safe place by simply flooring it and hit the brakes with the throttle on full, if your controller doesn't have a built in safety that cuts the throttle when the brake is pressed you have your answer. I personally know that my brakes can hold the car stationary in 2nd and 3rd, in 1st it creeps forward very slowly as the brakes can't quite hold the torque but with the front wheels locked there isn't much movement.


That sounds like a good description. 

Thanks, I will have to test this out once mine is built. I hope it never happens, but it is good to know.


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## Tesseract (Sep 27, 2008)

dladd said:


> Even with a manual pull cable or contactor disconnect button, in the scenario of something going full on just off the line while in traffic... well, you will hit the car in front of you before you can pull anything. Not much you can do about that I think.


Yep, I agree that the controller needs to automatically open the main contactor in the event of a power stage fault (or a short circuit, or too high of an input voltage, etc...) as humans aren't even close to being fast enough for this job. Any of the modern microprocessor based controllers which directly control their own main contactor for precharge purposes *should* be able to open said contactor in the event of a catastrophic fault, but whether they do or not is another matter entirely... My philosophy is that all power electronics devices will eventually fail - if nothing else, you can count on fatigue cracking from thermal cycling to do them in - so one should plan for that eventuality from the beginning.




Batterypoweredtoad said:


> Is it even slightly likely to fail full on while under very little load?


Sure, in fact it is more likely a controller will fail at low loads, both because the pack voltage will be near its highest and it is during the process of switching from on to off or vice versa that a semiconductor switch (including diodes) is at its most vulnerable. At max output the switch is likely to be on 100% of the time - no switching at all - so there is no handoff of current between the switch and freewheeling diode, no switching losses, and the pack voltage has likely sagged down a considerable amount; this is much easier on the switch than, say, being on 90% of the time or, even, just 10% of the time.


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## DIYguy (Sep 18, 2008)

cts_casemod said:


> What would happen if I experience a controller failure on a DC motor?
> 
> Souldnt be much of a problem in normal driving at 30MPH but lets supose you're stopped on trafic, 1st gear and while starting to moove the controller shorts. In first gear with the front car one meter away I dont think I can do anything to avoid crashing into it. This would happen in a fraction of a second.
> 
> Is this something I should be aware of? Please share your experiences!


Just to be clear and specific, the EVnetics controllers have a "brake input". When wired to your brake pedal switch, this circuit opens the main contactor(s) each and every time you apply the brakes. If you want to re-engage, you simply leave your foot on the brake pedal and reapply the throttle (for such things as burn-outs/brake stands ) 

So, in your case, and with an EVNetics controller properly installed, your first instinct would be to apply the brake. . . and more likely it is already on. So, the likelihood of your scenario happening with this controller is next to impossible.


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## major (Apr 4, 2008)

Tesseract said:


> Sure, in fact it is more likely a controller will fail at low loads,


Just saw this post. Happened to Willie pulling out of the garage. http://www.diyelectriccar.com/forums/showthread.php?t=77971


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## Tesseract (Sep 27, 2008)

DIYguy said:


> Just to be clear and specific, the EVnetics controllers have a "brake input". When wired to your brake pedal switch, this circuit opens the main contactor(s) each and every time you apply the brakes. ...


Erf, no... the brake input only overrides the throttle signal, it doesn't result in the main contactors opening up.


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## Tesseract (Sep 27, 2008)

major said:


> Just saw this post. Happened to Willie pulling out of the garage. http://www.diyelectriccar.com/forums/showthread.php?t=77971


Talk about a bizarre coincidence!? Poor little Willie... er.. that doesn't sound right, does it?


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## DIYguy (Sep 18, 2008)

Tesseract said:


> Erf, no... the brake input only overrides the throttle signal, it doesn't result in the main contactors opening up.


Ooops. OK. Thanks for clearing that up, Jeff. I guess the result is the same as in you cannot apply motor power. . . although the level of protection is certainly different.

I guess, it's still another level of protection.


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## Tesseract (Sep 27, 2008)

DIYguy said:


> Ooops. OK. Thanks for clearing that up, Jeff. I guess the result is the same as in you cannot apply motor power. . . although the level of protection is certainly different.
> 
> I guess, it's still another level of protection.


Interesting that you think opening the contactors would somehow be safer than overriding the throttle; in both cases you are *trusting* the microprocessor inside the controller to "do the right thing", so I don't see any difference in safety between those two actions, but I definitely see a difference in convenience (every time the contactors are opened the controller must go through the precharge process before closing them again, after all).

You also have to trust the microprocessor - and the code it runs - to open up the contactor in the event of a hardware failure. By all means you should have a manual emergency and/or service disconnect for the pack, but that should not be the first line of defense against something going wrong; more like the last resort!


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## DIYguy (Sep 18, 2008)

Tesseract said:


> Interesting that you think opening the contactors would somehow be safer than overriding the throttle; in both cases you are *trusting* the microprocessor inside the controller to "do the right thing", so I don't see any difference in safety between those two actions, but I definitely see a difference in convenience (every time the contactors are opened the controller must go through the precharge process before closing them again, after all).


Ahh, ok. I guess it's because I thought that the contactors would be driven directly for a safety and not through the processor. In industry, dual/redundant processors are used for safety applications. . . ones that constantly monitor the other. My head was stuck there I suppose.
Ya, waiting on pre-charge after each stop would be rather silly. lol



Tesseract said:


> You also have to trust the microprocessor - and the code it runs - to open up the contactor in the event of a hardware failure. By all means you should have a manual emergency and/or service disconnect for the pack, but that should not be the first line of defense against something going wrong; more like the last resort!


Yes, for sure. I wanted to get the emergency disconnect upfront also.


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## major (Apr 4, 2008)

Tesseract said:


> You also have to trust the microprocessor - and the code it runs - to open up the contactor in the event of a hardware failure. By all means you should have a manual emergency and/or service disconnect for the pack, but that should not be the first line of defense against something going wrong; more like the last resort!


In the E motorcycle race technical regulations, the "E-off" (or kill) switch can NOT rely on any processor or logic or software. It must either physically interrupt the power (battery) circuit or coil power to a contactor which does so. 

I have been in the driver's seat of a high power EV when a fault occurred "full on", in reverse, inside a large garage, not pointed out the door but rather close to a 10 ton machine tool. Full pressure from my leg on the brake pedal only locked the fronts and the rears were smoking like crazy pulling the car backwards. Fortunately I was able to hit the dash switch and save damage. But there were 2 thick black rubber stripes on the floor for a few years 

Even your common grocery getter EV motor can overpower the standard friction brakes when "full on". You need a no-brainer kill switch. When it happens, you don't have a lot of time to think about what to do. After my close call, I started putting an E-stop red button on the steering wheel of the race cars or on the handle bars of the race bikes.


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## Tesseract (Sep 27, 2008)

major said:


> In the E motorcycle race technical regulations, the "E-off" (or kill) switch can NOT rely on any processor or logic or software. It must either physically interrupt the power (battery) circuit or coil power to a contactor which does so.


Sure, fine - some rulebook says you have to have a manual kill switch. I did not say that wasn't acceptable, just that I wouldn't rely on THAT ALONE to protect me from, e.g., an internal fault in the controller. After detecting a fatal hardware fault a Soliton controller will have opened its internal contactors in around 10-20ms (in other words, the amount of time it takes the contactors to open up once the coil is de-energized).

If the technical specifications for E motorcycles prohibit the use of a microprocessor-controlled contactor in addition to a manual disconnect then - not to mince any words, here - these are stupid specs.

Just sayin'.


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## major (Apr 4, 2008)

Tesseract said:


> If the technical specifications for E motorcycles prohibit the use of a microprocessor-controlled contactor in addition to a manual disconnect then - not to mince any words, here - these are stupid specs.
> 
> Just sayin'.


I didn't say they didn't and they don't. You can have whatever system you want in addition to a manual circuit interrupt.


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## major (Apr 4, 2008)

Tesseract said:


> Sure, fine - some rulebook says you have to have a manual kill switch. I did not say that wasn't acceptable, just that I wouldn't rely on THAT ALONE to protect me from, e.g., an internal fault in the controller. After detecting a fatal hardware fault a Soliton controller will have opened its internal contactors in around 10-20ms (in other words, the amount of time it takes the contactors to open up once the coil is de-energized).


You know Tess? I think we agree here. The controller should do what you say. But in evaluating failure modes, I consider the chance the controller becomes one big short circuit in a box. What then? Another means to interrupt the battery power circuit is the safe recourse, wouldn't you agree?

maj


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## steve mauck (Aug 28, 2012)

Good discussion, fellows. Two things saved poor Willie from lurching out onto Main Street. He hit the kill switch and he kicked the gearshift up into neutral. I don't know which he did first. 

We are trying, now, to figure out why the main contactor stuck and how to keep whatever replacement we decide on from sticking also, from the same unknown cause. My contactor was a Tyco Kilovac 500 A 320VDC LEV 200 contactor. My batteries were ten 12 v O'Reiley's Marine Deep Cycle. So I was putting out 120 volts with a maximum of 500 amps. I do not know the brand name of my Motor Controller. The truck is over at Willie's. I know what is wasn't: a Curtis or Zilla. 

What I want to replace the Kilovac contactor with are a pair of Albright SW200 Contactors. They are only rated at 92 volts but the advertisement says they can be used "in multiples". I think that would work because it would spread the load between the two and would perhaps be less liable to spark and weld closed. The Albright brand is advertised as "rugged".

Could anyone comment on the Albright choice or suggest something different? 

When we next road test the S-10, we will pull it to an unused dirt road that we know about near town. No more "Main Street" experiments for us!


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## EVfun (Mar 14, 2010)

rwaudio said:


> I purposely did some burnouts in my 944 and it's not hard to hold the car stationary even if you're burning rubber. I would hope that hitting the brakes would be instinct in this situation and if you have decent reaction time you could stop the car in time assuming you have power brakes. In the time frames involved instinct would likely not make you hit an emergency disconnect lever/button in time to do anything, but as you sit there in traffic doing a burnout you have time to kill it calmly.
> 
> You could simulate this in a safe place by simply flooring it and hit the brakes with the throttle on full, if your controller doesn't have a built in safety that cuts the throttle when the brake is pressed you have your answer. I personally know that my brakes can hold the car stationary in 2nd and 3rd, in 1st it creeps forward very slowly as the brakes can't quite hold the torque but with the front wheels locked there isn't much movement.


Except for one thing...
When the controller fails full on you no longer have a current limit. Well, you do, but it is the short circuit limit of your battery pack!

I've had a Curtis 1221b controller fail full on. It happened right as I touched the throttle from stopped and I was in reverse. The Bug launched backwards and I smashed the brakes hard. The large rear tires where doing a burnout and the front tires where locked, sliding across the road. The current was 1200 amps or more, nothing like the puny 400 amp limit of the Cursit.


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## major (Apr 4, 2008)

EVfun said:


> I've had a Curtis 1221b controller fail full on. It happened right as I touched the throttle from stopped and I was in reverse. The Bug launched backwards and I smashed the brakes hard. The large rear tires where doing a burnout and the front tires where locked, sliding across the road. The current was 1200 amps or more, nothing like the puny 400 amp limit of the Cursit.


Seems to happen to us when in reverse  How did you stop? Fuse blow?

When it happened to me it was with AC. So I still had current limits and the fuse would never have blown.


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## Ziggythewiz (May 16, 2010)

Do you have a precharge on the contactor? It's possible for arcing to weld the contactor shut, and high inrush can also damage the controller.


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## major (Apr 4, 2008)

steve mauck said:


> Could anyone comment on the Albright choice or suggest something different?


Actually I think the Kilovac is a better choice. I have had that Kilovac contactor stick on when bench testing systems. It was caused by incorrect coil voltage and contact bounce, I think  Once I got the proper coil circuit, worked great. Incorrect (or lack of) precharge can cause contact damage resulting in stuck-on also.

Please post up your controller model.


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## Ziggythewiz (May 16, 2010)

major said:


> Seems to happen to us when in reverse


Guess that's a good reason to avoid reverse (in addition to my laziness)  I park in the back half of lots where I can pull through, and at one office I can point slightly uphill and roll back into a space. Wish I had a horseshoe driveway...


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## rwaudio (May 22, 2008)

EVfun said:


> Except for one thing...
> When the controller fails full on you no longer have a current limit. Well, you do, but it is the short circuit limit of your battery pack!
> 
> I've had a Curtis 1221b controller fail full on. It happened right as I touched the throttle from stopped and I was in reverse. The Bug launched backwards and I smashed the brakes hard. The large rear tires where doing a burnout and the front tires where locked, sliding across the road. The current was 1200 amps or more, nothing like the puny 400 amp limit of the Cursit.


With the extra load from the brakes I would expect (HOPE) the fuse would blow fairly quick in a situation like that. 
It is a good point that depending on the battery system the short term current could make some insane torque in a series DC motor.
My A123's for example would likely produce a few thousand amps for a short period of time, which in an 11HV would likely be 1000ft-lbs or more.

A properly rated fuse is likely the best fail safe for a shorted DC system, but like major said it wouldn't help with an AC system that is operating at full power but within the fuse limits.


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## dtbaker (Jan 5, 2008)

major said:


> You know Tess? I think we agree here. The controller should do what you say. But in evaluating failure modes, I consider the chance the controller becomes one big short circuit in a box. What then? Another means to interrupt the battery power circuit is the safe recourse, wouldn't you agree?
> 
> maj



ALL evs should have at least one fuse in middle of main pack, and circuit breaker with manual push/pull kill cabling... and inertia switch, key on/off on 12v side to kill main contactor KSI signal, over-speed interrupt optional but desirable if tach signal is available, and hopefully a clutch as last resort (which might cost you a motor if you cant pull the 'kill' in time).

I know the first time I 'finished' my enclosure for the pot box and all that, I put the lid on and noticed AFTER the fact that the tail of the throttle wire stuck up high enough to interfere with lid when it was a little 'lazy' returning to 0 one time in traffic. pretty scarey, but I was lucky enough to push clutch and pull kill cable in time before motor revved too high. A little embarrassing to kill the car in traffic at an intersection, but better than a crash. It was only at partial power, so not too scarey.


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## steve mauck (Aug 28, 2012)

Those are some scary stories! I am beginning to speculate that the failure that me and Willy had that sent us skidding and throwing gravel was not so much the Kilovac contactor failing but the Motor Controller failing. I did not have a Precharge before the contactor, unless a Precharge is a large 6000 microfarad capacitor? We do have the capacitor. I would guess now, after reading other experiences, that the contactor failed because the full amperage of the total battery pack hit the contactor, welding it closed. 

Back at the battery pack, we have a safety fuse, circuit breaker, and a safety interlock all in a line. I would have thought at least one of those would have interrupted the power.


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## Tesseract (Sep 27, 2008)

major said:


> You know Tess? I think we agree here. The controller should do what you say. But in evaluating failure modes, I consider the chance the controller becomes one big short circuit in a box. What then? Another means to interrupt the battery power circuit is the safe recourse, wouldn't you agree?
> 
> maj


Err... sure. It is within the realm of possibility that there could be a failure mode in which everything inside the controller becomes one big short circuit, but that's exactly the type of situation that *fuses* are intended to handle.

That said, I sort of get the impression you are trying to argue that the contactors inside the Soliton controllers are superfluous... Is that where you are going with this line of reasoning?


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## major (Apr 4, 2008)

Tesseract said:


> Err... sure. It is within the realm of possibility that there could be a failure mode in which everything inside the controller becomes one big short circuit, but that's exactly the type of situation that *fuses* are intended to handle.
> 
> That said, I sort of get the impression you are trying to argue that the contactors inside the Soliton controllers are superfluous... Is that where you are going with this line of reasoning?


No, not at all. I like them there. It is a good idea. But where I can, I use another contactor external to the controller controlled contactor. For me, the extra contactor goes in the battery negative line and comes on with the keyswitch. Then an enable switch tells the controller to precharge and light up. Normal shut down turns off the enable then the key. Like putting a car into park and then turning off and removing the key. 

On top of that, with some jobs, I add an E-stop. It depends on the system how the E-stop is implemented. For the racecar, it put the AC drive into base block. For the karts and bikes, it cuts the negative lead to the contactor coil. The racecar also had other kill switches outside to the rear for corner workers and first responders which killed power to the contactor coils directly.

I am 100% behind the idea of having the main contactor and precharge done by the motor controller both when those contactors are inside the controller box as you provide or outside like others use.

Most of the runaway EV incidents are not caused by a shorted motor controller. Most are human error. You know, mechanical problems. Like having a loose nut behind the wheel. Or a stuck throttle. Or pushing the wrong button or key on the computer.

If the motor controller shorts and the motor is in the circuit, there is a good chance the fuse will not blow, at least not right away. And even standing on the brakes won't load the motor enough to blow the fuse fast enough to avoid damage or injury. I'll keep the redundant contactor and/or a kill switch


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## GerhardRP (Nov 17, 2009)

major said:


> You know Tess? I think we agree here. The controller should do what you say. But in evaluating failure modes, I consider the chance the controller becomes one big short circuit in a box. What then? Another means to interrupt the battery power circuit is the safe recourse, wouldn't you agree?
> 
> maj


How about this possible solution: In series with the regular fuse, there is a fast blow fuse rated at the battery current draw at full throttle and say 1000 RPM. This second fuse is paralleled with a contactor that is normally open. The breaker closes, bypassing the fuse, when the RPM exceeds 750 RPM and the brake is NOT applied. The fuse blows on its own with a failure at low speed or upon brake application at higher speeds.
Gerhard


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## dtbaker (Jan 5, 2008)

steve mauck said:


> I did not have a Precharge before the contactor, unless a Precharge is a large 6000 microfarad capacitor? We do have the capacitor. I would guess now, after reading other experiences, that the contactor failed because the full amperage of the total battery pack hit the contactor, welding it closed.


why do you have a huge cap inline with your traction pack? unless you have a precharge resistor on that AND your main contactor, I think the in-rush to that alone will be a big problem as your main contactor closes never mind what controller you have...

I still don't see how any controller would fail 'full on' unless you had the throttle full on and IT failed. I can see how contactors could potentially weld shut if either closing or opening under high load.


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## DIYguy (Sep 18, 2008)

I'm in line with Major. Even with the Soliton, I always had a breaker (with selectable trip limits and remote shunt trip) wired to an E-stop mushroom button. Care must be taken where to locate this button! I use to hit it when shifting occasionally, and had to move it. 

Now that I have re-vamped the controls, of course I have the Evnetics controller, but the breaker is gone and I have a "set" of Tyco contactors to install in-line. I was planning to have the control side keyed as well as through the mushroom button. I was thinking to run this circuit to the back for race certification (when installed).

I also agree and like the pre-charge and contactors in the controller. 

To get the proper fuse for driving and expect it to blow with one event like this is highly unlikely. I recently blew an A50QS400 and it took about 6 hard accelerations to 1200 battery amps to do it. . . although they were spaced out a bit over a 10 - 15 min span.


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## EVfun (Mar 14, 2010)

rwaudio said:


> With the extra load from the brakes I would expect (HOPE) the fuse would blow fairly quick in a situation like that.
> It is a good point that depending on the battery system the short term current could make some insane torque in a series DC motor.
> My A123's for example would likely produce a few thousand amps for a short period of time, which in an 11HV would likely be 1000ft-lbs or more.
> 
> A properly rated fuse is likely the best fail safe for a shorted DC system, but like major said it wouldn't help with an AC system that is operating at full power but within the fuse limits.


The 300 amp fuse did not blow fast enough. I would done some serious damage first. The ignition switch saved that day, opening the Albright SW200 main contactor. The contacts where a bit cooked, but did their job well. 

The problem is that once the car starts moving the motor starts making back EMF that then limits amps -- to just more than the brakes can handle (because as the motor slows the current and torque rises.) The fuse won't be "instant" until about 10x its rating. High current DC fuses are generally quite slow to blow. A few seconds is an eternity when this happens.


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## Tesseract (Sep 27, 2008)

major said:


> ...If the motor controller shorts and the motor is in the circuit, there is a good chance the fuse will not blow, at least not right away. And even standing on the brakes won't load the motor enough to blow the fuse fast enough to avoid damage or injury. I'll keep the redundant contactor and/or a kill switch


That depends. If the semiconductor switch has failed on then, yes, the motor will likely not allow enough current to be drawn to blow the fuse fast enough to matter, but I was addressing the scenario you imagined where the entire inside of the controller has turned to slag; in that situation there are multiple pathways for current to flow besides the motor and the fuse should blow in short order.



dtbaker said:


> ...I still don't see how any controller would fail 'full on' unless you had the throttle full on and IT failed. ....


The reason this can happen is because semiconductor switches typically fail in the "shorted on" condition, and the most common causes of this failure are avalanche (ie - overvoltage) and thermal runaway.


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## major (Apr 4, 2008)

dtbaker said:


> steve mauck said:
> 
> 
> > Those are some scary stories! I am beginning to speculate that the failure that me and Willy had that sent us skidding and throwing gravel was not so much the Kilovac contactor failing but the Motor Controller failing. I did not have a Precharge before the contactor, unless a Precharge is a large 6000 microfarad capacitor? We do have the capacitor.
> ...


It is sounding like one of those EPC controllers


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## Ziggythewiz (May 16, 2010)

major said:


> It is sounding like one of those EPC controllers


My thoughts exactly.


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## EVfun (Mar 14, 2010)

A bit about why a Curtis controller is most likely to fail at low speeds:
Inside a DC Controller by Lee Hart


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## steve mauck (Aug 28, 2012)

major said:


> It is sounding like one of those EPC controllers


I checked to see what I had. It is indeed an EPC 1000! Actually, I am learning a lot as I read other people's similar experiences. It looks like there is no handbook for the Electric Vehicle because no two are alike. 

I'm not even sure my Kilivolt Contactor is fried, now. A charge from my huge capacitor may be holding it closed. Tomorrow I will build a 60 watt light bulb resistor and discharge that capacitor and see if my contactor opens.


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## Ziggythewiz (May 16, 2010)

Can't you just disconnect it for testing? The capacitors could not keep it closed for long. That whole capacitor bank probably stores less energy than a AAA battery.


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## dtbaker (Jan 5, 2008)

steve mauck said:


> I'm not even sure my Kilivolt Contactor is fried, now. A charge from my huge capacitor may be holding it closed. Tomorrow I will build a 60 watt light bulb resistor and discharge that capacitor and see if my contactor opens.




??? is the cap on the high voltage side, or the 12v side? why don't you just take it OUT? how would charged cap hold your contactor closed?

I tried a cap for a while on the 12v side to alleviate temp voltage sag when vacuum pump came on.... but I think the repeat inrush to recharge the cap killed my dc-dc.... I have switched to a small ATV battery in parallel w (always on) dc-dc; seems to work WAY better.


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## Ziggythewiz (May 16, 2010)

EVfun said:


> A bit about why a Curtis controller is most likely to fail at low speeds:
> Inside a DC Controller by Lee Hart


Ah...the soothing whine of a slow clock


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## major (Apr 4, 2008)

steve mauck said:


> I checked to see what I had. It is indeed an EPC 1000.


That is unfortunate. There is a member PZigouras who was promoting these controllers a while back. I and others tried to warn people about the crap he was passing off. Do a search for PZigouras and read some of those threads.


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## dtbaker (Jan 5, 2008)

Ziggythewiz said:


> Ah...the soothing whine of a slow clock



thats the parking lot 'warning noise' for pedetrians!


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## DIYguy (Sep 18, 2008)

steve mauck said:


> I checked to see what I had. It is indeed an EPC 1000!


Dump it and get an actual controller. That thing is an accident waiting for a place to happen, errr ahh. . . again. Honestly, u don't want that thing.


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## dtbaker (Jan 5, 2008)

DIYguy said:


> Dump it and get an actual controller. That thing is an accident waiting for a place to happen, errr ahh. . . again. Honestly, u don't want that thing.



if you are REALLY scrimping, look for a Curtis, even a used one.... relatively bulletproof, but a little anemic. mmmmmm, I HAVE one on the shelf I haven't put on classified yet.

or.... go for a zilla or soliton.


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## steve mauck (Aug 28, 2012)

Oh My Heavens! I just took a couple of hours to read the several months of posts with Paul Zigouras. Of course that piece of junk is coming out of my electric S-10! That creep tried to kill me and Willy. This project is our first rebuild. We bought a used truck with the kit unused and still boxed up. The EPC 1000 was the motor controller. My only previous electronic experience is repairing and rebuilding antique tube radios. Willie's experience comes from being a general maintainance man at his work. Still, I imagine that we probably represent the average home brewers of electric vehicles. We take things at face value. We thought the "motor controller" was real. It nearly killed us, especially Willy. That E pic P iece of C rap 1000 goes into the trash in the morning. I'll be looking for a REAL motor controller. 

My heartfelt thanks to you folks on the forum for taking the time to thoroughly interview Paul Zigouras and expose him for the fake he is.


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## Qer (May 7, 2008)

steve mauck said:


> I'm not even sure my Kilivolt Contactor is fried, now. A charge from my huge capacitor may be holding it closed. Tomorrow I will build a 60 watt light bulb resistor and discharge that capacitor and see if my contactor opens.


Sounds like it's welded shut. A cap shouldn't be able to keep the contactor closed for hours, more like seconds. Not surprised considering the current rush.



steve mauck said:


> Oh My Heavens! I just took a couple of hours to read the several months of posts with Paul Zigouras. Of course that piece of junk is coming out of my electric S-10! That creep tried to kill me and Willy.


As associated to a controller manufacturer I'm very careful not to debate the pros and cons of our own or our competitors controllers, but there's always exceptions to every rule and EPC is my exception. It's a real piece of shit. Period.

You've been very unlucky, or very lucky depending on how you look at it. All stories I've heard of the EPC the controller has just blown and turned into a paper weight (probably because of the feeble build that can't handle the power of a short for long), yours is the first I can remember where the EPC actually turned into a runaway monster. With the exception of PZs self promotion I've never actually heard of success stories where the EPC actually did what's promised.

I'm all for ripping that crap out of the S-10 and being replaced by a well built controller, however I hope that you don't throw it in the garbage but instead keep it as proof and that you will take the time to inform the kit seller and whoever else selling these dangerous scams (e-bay for example?) what happened to you before someone gets killed by PZs "products".

So, go for a known good brand and your S-10 will run just fine. Just keep in mind that the S-10 is a relatively heavy car so a controller that's well suited for a smaller car might make your S-10 rather sluggish. There's a few S-10's on evalbum.com and some of them mentions the acceleration, like this one:

http://www.evalbum.com/3869

The controller specs are 600 Amps peak, 300 Amps continuously, which results in an acceleration the owner refers to as "Mild. 0 to 60 in under 10 minutes!". Let's hope he's exaggerating. 

Anyway, you ended up with the simple worst possible "controller" available. No matter what you choose as a replacement it ought to be a better one. Like a working one...

Welcome to the forum btw. Most brands, problems and solutions are discussed here. Just search the forum.


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## major (Apr 4, 2008)

Qer said:


> I'm all for ripping that crap out of the S-10 and being replaced by a well built controller, however I hope that you don't throw it in the garbage but instead keep it as proof and that you will take the time to inform the kit seller and whoever else selling these dangerous scams (e-bay for example?) what happened to you before someone gets killed by PZs "products".


Well said Q. I would like to know where steve bought this brand new "kit". I wish I knew of some way we could shut down EPC or warn potential customers. I see eBay listings for their crap being sold by EPC to this day. And they have only positive feedback Paul Zigouras is a scumbag making a buck at the expense the EV hobbyist and doesn't care that his crap will injure or kill somebody  

Steve might be able to file a complaint with the state attorney since he is an actual customer. He could use some of the threads from this forum to show that PZig was warned about the nature of his crap.


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## cts_casemod (Aug 23, 2012)

Guys, no mater what we do and how much safety we have if such a situation happens in bumper to bumper traffic there is no way not to smash against the front car. Where I live at London this is my everyday.
I do not drive one meter from the front car but I stop one meter or less from the front car in bumper to bumper traffic.

I suggest anyone with a DC motor to place the contactor wired with the brake switch. I wouldn’t trust ANY controller. If the worst happens at least you have a better safety to press the brake until you can look for the kill switch, switch the ignition off, etc. Burning rubber doesn’t make any sense. If you want to do regenerative braking place a suitable diode between the battery and the controller so that the current only flows one way, but most DC conversions don’t do this anyway. 

Fuses and all protections will take too long to blow and the motor may draw 1000-1500Amp if the batteries can supply. 

Thank you to all of you for sharing experiences, I was worried about this, but never actually thought the problem to be so common/serious. Its a good thing this forums are here. 

I will go the AC route, if this happens on a AC system the motor will simply lock. Its not worth to pay 700£ Excess in my insurance premium to try to save a few bucks on the motor.  
Some very interesting topic is using an industrial AC phase motor and a VDF. There is a guy in here running a modified one in his Passat and he claims 90HP. It Certainly looks very good.
The very popular AC50 is a 7 or 9KW AC Motor with 60HP peak, rewound to low voltage AC, so this looks promising.


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## Qer (May 7, 2008)

cts_casemod said:


> I suggest anyone with a DC motor to place the contactor wired with the brake switch.




That's a terrible advice!

That means that every time you brake, the contactor opens, the caps drain and every time you release the brakes the contactor will close and the current will spike, hurting both the contactor and the caps. Eventually you might end up hurting the capacitors so bad that they age prematurely which will increase the risk for the controller to blow up, resulting in exactly the situation you want to protect yourself from.

I'd guess all micro controller based controllers will detect the sudden lack of pack voltage and shut down, since it's not good for the caps...




cts_casemod said:


> I will go the AC route, if this happens on a AC system the motor will simply lock.


IF it's a transistor that short out, yes. If it's a software problem there's no such guarantees and the more features in a controller, the more complicated software and thus also harder to verify that the software is safe. In post #23 in this thread Major mentions his own experience with a runaway AC inverter, so there's no guarantees that just because you pick AC you'll be safe.

Then there's other causes for runaway situations, like a stuck throttle, broken wire, human errors etc etc etc. A GOOD micro controller based motor controller has possibilities for more safety systems than an analogue controller but a badly designed controller will never be safe, no matter what kind of motor it controls.

But no system is 100% fail safe. Ask Toyota...


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## cts_casemod (Aug 23, 2012)

You're right that would be a terrible idea, but you've assumed I meant to disconnect the full pack from the controller, which I don’t. 
I meant *using a separate contactor ONLY between the **controller output* and the DC *motor imput*. There should be no power flowing there, when you apply the brakes as the controller disables the motor when you brake anyway, some of them with an internal contactor as well, but I rather prefer a manual option as an *ADDED* safety feature if everithing else fails.

The controller DC imput and associated capacitors would be *powered all the time*, as well as all the other electrics on the vehicle.

For a throttle to stay fisically stuck in full on position you need to press the accelerator fully. As someone said before if you are driving at a decent speed you may apply the brakes just in time to reduce the speed and hit the panic button. If you are reversing you're not going to have time for this, BUT you will not apply full throttle and you will press the brake when you want to stop anyway.

I am a vehicle mechanic and in every single car you have two tracks on the electronic throttle, wich are compared by the vehicle ECU and if a difference between them is found the car goes into limp mode and the engine runs with limited power, eg: only able to idle or rev up to 1500RPM, etc.
And Yes, this happens frequently after 50 to 70.000 miles. A good controller should do this as well, both on DC and AC, but guess what, most EV controllers don’t...! 

Software issues may be present on both on AC or DC motors, so we are even... DC motors may as well go full throttle if there’s a problem in the software or the tracks on the throttle. Thats a price to pay for all the electronics. They may save you, but they may also fail and start acting crazy.

At the end of the day there are no flawless systems, I just prefer to go by the safest route, and in case of controller failure a DC motor will output as much as the battery may supply, an AC motor will stall. That’s at least one advantage the AC system has over the DC.


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## PStechPaul (May 1, 2012)

I just read this entire thread and it was a real eye-opener. I have a few observations and suggestions.
If you keep the clutch and a M/T, at the first sign of a runaway motor the instinct is to press the clutch and the brake, which should quickly stop the car safely. But probably not fast enough to avoid a crash in slow traffic.
An AC system is inherently safer because a shorted IGBT will just apply DC to the motor and the current will quickly blow the fuse, while the motor will instantly stop.
For a DC motor, the controller should have a reasonable maximum current limit, and the battery fuse should be a semiconductor fast-blow type of that rating which will blow in less than 1 second at 4x. http://www1.cooperbussmann.com/library/bifs/17056318.pdf
An electronic motor protector can be set to trip in less than 0.1 second at 2x rated current: http://static.schneider-electric.us/docs/Circuit%20Protection/Motor%20Circuit%20Protectors/1200%20A%20Frame%20PJL-PLL%20Mag-Gard/613-11.pdf
This danger is a good reason to limit the maximum torque and acceleration to reasonable levels rather than the "fun" performance specs that many like to brag about. Racing should be done on tracks. Public roads should be for safe driving.


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## EVfun (Mar 14, 2010)

That fuse blow time you want isn't easy to accomplish. For the Zilla 1000 amp controllers Otmar recommended a 500 amp A30QS fuse (for lower voltage systems.) That would blow in about 0.1 seconds at 2000 amps, but take about 40 seconds to blow at 1000 amps. This is where DC can get exciting. The brakes slow the motor until the amps and torque rise to meet the brake force.

I'm sure the Soliton controllers have some internal safeties employed to catch a runaway and shut down. The Zilla controller switch the IGBTs off briefly several times a second even when full on (99.99% on?). If the Hairball doesn't "see" the current across the IGBTs stop then it will open the main contactor. I think it is designed to shut things down within a 1/4 second of a lock on failure. These full on problems are mostly confined to the older analog controllers like the Curtis 1221 and 1231. 

So an electric motor protector is a good idea, and can be built into the controller. 1000 amps seems like perfectly reasonable acceleration for a 1200 lb. car to me.


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## circuit (Jan 16, 2012)

My colleague built his DC controller for his Honda 3E conversion:
http://hr-ev.blogspot.com/
He implemented three degrees of protection:
#1 active current limiting
#2 separate circuitry for output monitoring
#3 a mechanical killswitch.

Actually the #2 is the smartest thing about the protection. This circuitry monitors the output of the controller and if it detects invalid PWM, immediate KillAll signal is sent to main contactor. It is so fast that you would hardly notice the punch in case of failed power transistor.
There is also a leakage detector that also kills the power if abnormally high current leakage is detected (for example if any of the wires is damaged due to any reason, such as fire or crash).
And if those fail, you have the kill switch...


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## PStechPaul (May 1, 2012)

The most dangerous thing is the nut behind the wheel. DIYers at least have some idea about how cars work and should be able to take care of a problem like full-on acceleration. But you can't make a system idiot-proof. Devolution just creates better idiots. Take the following for example:

http://www.ksla.com/story/19395867/woman-trapped-in-suv-with-stuck-accelerator

This was probably a case of the floor mat or some other object causing the accelerator to stick. It's happened to me in an old truck where the linkage went through a hole in the floor. And sometimes the linkage just got balky and I was used to hooking my toe under the pedal to pull it back up. Otherwise since I have almost always had a manual tranny I could just disengage the clutch or put it in neutral or turn off the key. And in most cases, too, the brakes should stall the engine if you apply them hard enough.

I think the case above was driver panic combined with cluelessness, and the 911 operator was probably not all that savvy either, since it took a half hour before somebody suggested pulling up on the pedal, which worked a charm. It's possible that anti-lock brakes may have prevented them from stalling the motor. And perhaps there were interlocks on the shifter and the ignition key that prevented those obvious remedies. I think some cars now just use a keyless ignition. Too much technology and not enough common sense can be a dangerous combination!


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## Qer (May 7, 2008)

Hm? Didn't I answer this already? Apparently not.



cts_casemod said:


> You're right that would be a terrible idea, but you've assumed I meant to disconnect the full pack from the controller, which I don’t.
> I meant *using a separate contactor ONLY between the **controller output* and the DC *motor imput*.


I would definitely recommend against this as well. There's definitely a risk that if you release throttle when the car is moving, the inductor in the motor is still generating some back-EMF and when the contactor opens it turns into a spark gap.

Another problem would occur when you apply throttle at the red light. The reaction time of a contactor is extremely sluggish compare to the near instant reaction time of software so by the time the contactor closes the PWM is already running. I can only speculate how other controllers will react on this but the Soliton will already have jacked up the PWM quite a bit due to lack of current so when the contactor finally closes the resulting current will turn into a serious jolt that in the long run probably will wear out the contactor, not to mention that the controller probably (depending on the peak current) will throw an error and close down.

The Soliton EXPECTS the circuit to always be closed (unless, of course, when it KNOWS it isn't). Breaking and closing the circuit at a whim just like that will, definitely, be a very bad thing considering the currents and voltages we're talking about. I would guess that other CPU based controllers will react badly as well and the experiences based on dumb analogue controllers simply aren't applicable on todays more "intelligent" systems.



cts_casemod said:


> A good controller should do this as well, both on DC and AC, but guess what, most EV controllers don’t...!


Unfortunately we followed what was already customary on the market and changing that now isn't instant. Hind sight's 20/20 and all that...

That's why the brake input of the Soliton shuts off the throttle immediately. It's not perfect, but it's a good safety feature since your first instinctive reaction will be to hit the brakes. It doesn't replace dual throttle wires, but it definitely limits the risks involved.



cts_casemod said:


> Software issues may be present on both on AC or DC motors, so we are even...


I think you're not aware of exactly how much complicated software for AC-inverters has to be. There's a potential for a lot of more screwups in the noticeably much more complicated code so it's definitely not even.

To be fair most screwups in both cases will likely lead to blown electronics or a non-moving car than a runaway situation, but no matter that it's still a lot more complicated to correctly control an AC motor than a DC motor with a much bigger potential for fatal mistakes.



cts_casemod said:


> At the end of the day there are no flawless systems, I just prefer to go by the safest route, and in case of controller failure a DC motor will output as much as the battery may supply, an AC motor will stall. That’s at least one advantage the AC system has over the DC.


In case of a shorted transistor, yes. Then you're correct.

That was the classical fault 1A back in the analogue days and when I started to read this forum it was scaringly common. Today pretty much all high power controllers has a CPU (let's just for a second pretend PZs contraption doesn't exist) which means that all (sanely) designed controllers does it's best to protect the software, for example by temperature derating, which means that blown transistors are much more unlikely today than, say, 5 years ago.

When the complexity of the software has gone up, so has of course the likelyhood for software screwups and the risk for a runaway or other dangerous situations are more likely to be the result of sloppy software (or mistakes in an otherwise well designed program) so the difference between the mechanical/electrical solutions has decreased while the software poses an increasing risk instead. Quite analogue to the continuous trend among gassers as well; fewer and fewer problems are mechanically related and it's increasingly common cars suffer from software related problems instead.

Theoretically you could argue that an AC system is still safer because there's a bigger treshold to get AC to work and you would be partly right. Unfortunately that theory is torpedoed by example code that is provided by the CPU manufacturers and often you can just cut and paste this code and add your personal spaghetti code on top of this, which means that if you're a completely incompetent programmer that is just competent enough to actually patch some Frankenstein-code together you have the potential to actually create a WORSE monster than if you went the DC-route and had to write the code from scratch.

I see this in RL pretty often, since I work with embedded systems more or less daily. You REALLY don't want to see what kind of software contraptions that control our washing machines, micro wave ovens, cars, elevators, you name it. There are times I'm amazed people don't die like flies in a honey trap because, really, the code quality in the industry in general is dystopical, founded more on happy thoughts and luck than on genuinely sane principles and careful testing before release.

There's this view of the machines taking over, enslaving humanity. I'm definitely more afraid of the machines running amok, crushing people because our own incompetence and total lack of "what if"-thinking...

Then there's the other side of security. Most of the cases perceived security is much more important than actual security. Studies tells us that if you feel insecure, this is a stress situation that will have a very dangerous impact on our bodies. Seen from that perspective you should probably choose AC since you apparently see them as safer. By choosing AC you will have an easier time to relax while driving which will lower your level of stress which has direct health benefits for you and also probably will decrease the risk for you to experience an accident.

So, well, I'm not saying choosing AC is a bad thing. Subjectively speaking it might even be a very good idea. At least for some people.


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## SandRailEV (May 11, 2012)

Qer said:


> Hm? Didn't I answer this already? Apparently not.
> 
> 
> 
> ...


 
That's one impressive pile of double-talk right there... Congrats...


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## Ziggythewiz (May 16, 2010)

Qer said:


> Then there's the other side of security. Most of the cases perceived security is much more important than actual security.


Speaking of security, what do Soliton's use, password etc? If someone like me (hacker by trade) but less ethical were to show up at say EVCCON or a drag strip and saw WiFis named soliton and started poking, is stuff protected?


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## Tesseract (Sep 27, 2008)

SandRailEV said:


> That's one impressive pile of double-talk right there... Congrats...


Looks like someone is itching to get hit with the ban hammer...




Ziggythewiz said:


> Speaking of security, what do Soliton's use, password etc? If someone like me (hacker by trade) but less ethical were to show up at say EVCCON or a drag strip and saw WiFis named soliton and started poking, is stuff protected?


The Soliton controllers are not protected at all and for this reason we don't encourage/support connecting our controllers to a WiFi-enabled router and/or an Ethernet to WifI bridge. If you choose to do so it is entirely at your own risk and with the full understanding that the controller is a sitting duck for any malicious activity directed at it, intentional or not.


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## Ziggythewiz (May 16, 2010)

That's what I thought. Was just curious as Jack had demo'd how easy it was, so I'm sure many of his followers listening themselves smart will assume that's the way to go.


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## Qer (May 7, 2008)

Ziggythewiz said:


> That's what I thought. Was just curious as Jack had demo'd how easy it was, so I'm sure many of his followers listening themselves smart will assume that's the way to go.


That is, indeed, a risk worth considering. My suggestion is to activate the routers security and for example use WPA2-encryption (not WEP since it's utter crap) with a reasonably long password. Reasonably long being defined as:

http://xkcd.com/936/










This is actually the most pedagogic password advice I've seen. Use it, and not only for WPA2 passphrases.


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## SandRailEV (May 11, 2012)

Tesseract said:


> Looks like someone is itching to get hit with the ban hammer...


Not really. The post I quoted is full of non-facts and false information. Re-read it carefully. 

For instance: QUOTE: There's definitely a risk that if you release throttle when the car is moving, the inductor in the motor is still generating some back-EMF and when the contactor opens it turns into a spark gap.

Note that it was stated that the safety contactor is CONTROLLED by the BRAKE pedal, not teh gas pedal. Therefore, the safety contactor would only de-energize when the brake is applied, AFTYER the controller stopped PWM output.

And another quote: Another problem would occur when you apply throttle at the red light. The reaction time of a contactor is extremely sluggish compare to the near instant reaction time of software so by the time the contactor closes the PWM is already running. I can only speculate how other controllers will react on this but the Soliton will already have jacked up the PWM quite a bit due to lack of current so when the contactor finally closes the resulting current will turn into a serious jolt that in the long run probably will wear out the contactor, not to mention that the controller probably (depending on the peak current) will throw an error and close down.

Again, assuming one takes his foot off of the brake before hitting the accelerator, the safety contactor has already been energized and closed before the controller outputs PWM. Also consider that a contactor closes and open in miliseconds, likely 50 or so. That's quite a bit faster than it would take most people to move their foot from the accelerator to the brake or vice-versa. Not exactly sluggish...

Therefore, the safety contactor is never hot-switched UNLESS there is a safety incident at which point there is already a controller failure. 

Then there's the whole thing about safety being a feeling rather than a reliable system, yadi yadi yadi....

Quote: Most of the cases perceived security is much more important than actual security. Studies tells us that if you feel insecure, this is a stress situation that will have a very dangerous impact on our bodies.

So, no, not itching to be banned, only pointing out that the post was a bunch of double-talk...

Personally, I tink the safety contactor is a good idea if sized and installed adequately.

But, to each his own....


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## Tesseract (Sep 27, 2008)

SandRailEV said:


> Not really. The post I quoted is full of non-facts and false information. Re-read it carefully.


Ok, if you say so...



SandRailEV said:


> For instance: QUOTE: There's definitely a risk that if you release throttle when the car is moving, the inductor in the motor is still generating some back-EMF and when the contactor opens it turns into a spark gap.
> 
> Note that it was stated that the safety contactor is CONTROLLED by the BRAKE pedal, not teh gas pedal. Therefore, the safety contactor would only de-energize when the brake is applied, AFTYER the controller stopped PWM output.


Actually, it will take several hundred milliseconds for the current in the typical DC motor to decay to zero after the PWM'ed switch turns off. The length of time depends on the current flowing through the motor prior to switch turn off, the inductance of the motor, and the voltage across it (which is clamped by the freewheeling diode during the off time of the switch, usually to around -1 to -1.5V). In contrast, the EV200 contactor typically opens within 20ms, so there exists the possibility for mayhem to ensue if you put a contactor in the motor circuit which opens up every time the brakes are applied. Granted, one must also consider the amount of time it takes to move your foot from from the accelerator to the brake, but I, personally, would not want to bet that it will always take longer for someone to move their foot than it will for motor current to decay to zero, especially in motors wound for high voltage (like Kostov's) and/or when motor current started off at a high value (e.g., 1000A).

And there are vehicles with automatic transmissions and/or other "engine driven accessories" which need to be idled. Having the brakes open up the motor circuit wouldn't work too well then, now would it?



SandRailEV said:


> And another quote: Another problem would occur when you apply throttle at the red light. The reaction time of a contactor is extremely sluggish compare to the near instant reaction time of software so by the time the contactor closes the PWM is already running....
> 
> Again, assuming one takes his foot off of the brake before hitting the accelerator, the safety contactor has already been energized and closed before the controller outputs PWM. Also consider that a contactor closes and open in miliseconds, likely 50 or so. That's quite a bit faster than it would take most people to move their foot from the accelerator to the brake or vice-versa. Not exactly sluggish...


A fair point, and one worthy of arguing, but it's not even close to what I would call double-talk. Qer wasn't using confusing verbiage to obscure his real meaning (except insofar as English is a second language for him, but that does not appear to be a factor in this instance).



SandRailEV said:


> Then there's the whole thing about safety being a feeling rather than a reliable system, yadi yadi yadi....


I presume, then, that you are one of those people that thinks our airports are safer now that everyone has to take off their shoes, pass through a millimeter wave scanner, can't bring more than 4oz of any one liquid in their carry-on luggage, etc.?

Whatever. The point of this forum is to help people convert ICE cars to electric; it wouldn't hurt to keep that in mind before posting, especially something that is likely to be construed as rude.


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## SandRailEV (May 11, 2012)

You have your opinions, I have mine....


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## EVfun (Mar 14, 2010)

SandRailEV said:


> That's one impressive pile of double-talk right there... Congrats...


Wow, so you're gonna school controller manufacturers on how it's done? 

I'm gonna make some popcorn and watch the show.


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## SandRailEV (May 11, 2012)

EVfun said:


> Wow, so you're gonna school controller manufacturers on how it's done?
> 
> I'm gonna make some popcorn and watch the show.


Oh how could I have forgotten that manufacturers make no mistakes and always provide the very best of everything with no room for additional features? 

Please forgive me for being so stupid while you're so smart...

I should have recognized your godliness...

Please ban me now before I say something stupid again...


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## EVfun (Mar 14, 2010)

1. I'm not a controller manufacturer.

2. I'm not in a position to ban anyone.

3. That would ruin the show.


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## Qer (May 7, 2008)

SandRailEV said:


> Oh how could I have forgotten that manufacturers make no mistakes and always provide the very best of everything with no room for additional features?


Nope. We do several mistakes like every other human, that's what the dyno is for because thankfully most of our mistakes (especially some really bad ones) are caught there. Being rude or snide is, however, not a luxury I normally can afford myself since the reputation of EVnetics on this forum and in the community partly lies on me.

The problem with your advices is that they are potentially dangerous should someone try to implement them without fully understanding the implications and pit falls, hence I pretty much was forced to reply to you to point out why it was not such a great idea that it might sound like.

If the Soliton supported and could control a contactor that broke up the motor circuit in a controlled manner (ie never open it before the current has dropped to zero and always give the contactor time to close properly before the PWM is activated) it could be argued that this would be an increased security feature, but then we would be back to the situation that the system would be sensitive to software errors.

When it comes to safety I try to follow the KISS-rule. In this case the KISS-rule is implemented as that no matter what fault is detected by the controller, the PWM is killed and the contactors (contactor in Jr) are immediately released. There has been requests of non-fatal errors (ie only logged on the web page without shutting down the controller) but I've refused to change this behaviour because I don't want to risk screwing up calling the "wrong" error, thus "forgetting" to shut down the high power side. An error is fatal, period. KISS.

This is, as I see it, the absolute best approach in any controller; the contactors should be operated by the controller since the controller software will react much faster on a detected hardware error than any human can, thus avoiding a potentially lethal position before it even occur. If the doesn't detect the hardware error or the software itself is the cause adding more contactors won't really make a difference since the whole point of adding software is to make the hardware more reliable by, for example, making sure the precharge process is fail safe, shorted transistors are detected in time etc.

This is why the contactors (and possibly the whole controller) should be powered in a way that makes it easy for the driver to kill the power; if there's no power to the contactors they will automatically open, thus the driver can stop the car from going Frankenstein on the humanity. This is also the way we recommend adding extra contactors to the system; they should be connected to the same power source as the Soliton so the contactors close in time before the precharge cycle and opens immediately when the ignition is turned off, preferably also with an added collision detection switch that cuts the power the same way; to contactors and controllers at the same time.

...aaaand I'm late to work so I have to cut it short here. *wave*


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## TigerNut (Dec 18, 2009)

In many motorsport situations it's common to apply the throttle and brake simultaneously, even if only momentarily, to achieve a particular vehicle attitude. Having the PWM automatically go to zero when you touch the brakes is one thing; this is probably the desired behavior even in the competition situation. But if you had the contactor control tied to the brake input then that would slow the response time of the driveline down in a big way, in addition to causing the mechanical and electrical damage to the contactor.

What is the stated lifetime (in cycles) of a big contactor? I built a RF testing setup for work, where we switch radio signals using RF relays. The mechanical relays have a stated life of about a million cycles... sounds good, until you realize that one RF test requires switching about 200 times and doing a radio development might require 100 tests. Now the life of one relay is 50 developments.

How many times do you hit the brakes going to work?


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## albano (Jan 12, 2009)

TigerNut said:


> How many times do you hit the brakes going to work?


Good point here....


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## Qer (May 7, 2008)

TigerNut said:


> How many times do you hit the brakes going to work?


Also; if there's current flowing, even if it's just a tiny bit of a current compared to the rated specs, this will wear out the contactor even faster. If you break the motor circuit when the motor inductor is still keeping the motor current to flow after PWM is shut off, there will be a little spark every single time you open the contactor, it will actually behave a bit like the spark plug circuit in a gasser. There are contactors that are made for breaking high current repeatedly (with a matching price tag), but they still wear down, eventually...

This is also one of the reasons why a good precharge routine gets more important with higher pack voltage, especially with capacitor that has internal resistance of fractions of an Ohm. The higher the pack voltage and the lower the internal resistance in the capacitors, the harder the contactors and capacitors get hit every time the controller is activated. A well designed precharge circuit will keep the wear of the contactor to a minimum.

On a low volt system in, for example, a golf car with lead acid batteries and pretty small electrolyte capacitors it's ok (not good, but ok) to open up the contactor every time you release the throttle and just slam it shut without any precharge, the comparatively high resistance in the batteries and the capacitors will limit the current to relatively low levels. In todays DIY EV with high pack voltage, Lithium batteries and modern capacitors your contactor replacement budget will quickly turn into the main maintenance cost of your EV...


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## PStechPaul (May 1, 2012)

One minor point on DC motor control with a contactor is that a fast commutating diode across the motor (inductive load) will eliminate the high voltage inductive kick that can cause a large arc and contact damage. The motor's generated voltage will be less than the battery voltage, and essentially nothing for a series wound DC motor. And a snubber across the contacts will further reduce any problems. I should make a "short" video demonstrating this with an inductor and a small series wound 12V motor.

But in any case I don't think it's a good idea to open a contactor in series with the motor except in emergency failure situations. And in that case it may even be best to apply a solid short circuit across the motor which will cause immediate dynamic braking and also current sufficient to blow the battery pack fuse.


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## david85 (Nov 12, 2007)

It seems like a simple and elegant concept to use a main mechanical disconnect that unplugs the battery everytime you let off the pedal, but in reality, you are relying on a mechanical, arcing contactor switch that has a SIGNIFICANTLY lower number of cycles before it fails. 

Can you time it such that the duty cycle reaches absolute 0% everytime before opening the relay? probably. But what about when the light turns green and you have to go through precharge again? Can you sustain the charge in the capacitor bank such that you can immediately close the relay? maybe, but what if something goes wrong and the caps discharge while waiting for the lights to turn? There are too many added potential failure modes for this to be considered a safety feature.

In my car, I use a main contactor switched to the ignition which will open or close whenever the ignition is turned off or on respectively. The Soliton has its own internal precharge and will power on gently all by itself once the main is closed. If the controller ever does jam on full, I need only switch off the ignition to kill the motor (the 450 amp fuse may do this for me by the time I reach for the key, however). But until then, the main contactor will never be subject to a full or partial load disconnect. 

This will keep the main contactor in gentle service so that if and when an emergency does happen, it will not be worn out by dozens or even hundreds of daily cycles in normal driving.


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## major (Apr 4, 2008)

PStechPaul said:


> One minor point on DC motor control with a contactor is that a fast commutating diode across the motor (inductive load) will eliminate the high voltage inductive kick that can cause a large arc and contact damage.


I would caution anyone considering this to check with the controller maker because adding an external diode may interfere with the proper operation of the controller's FWD.

Also, note that contactors in the motor loop are quite common in applications requiring motor reversing. That is where the reversing contactor set is installed. They typically are normally open and pull in with the F/R switch before PWM and remain engaged until the motor has been de-energized. In the past, these F/R contactors were allowed to open and close under load for plug reversing in such applications as forklifts. And yep, they sparked.

For EV cars, I think it is a bad idea to use a contactor in the motor loop unless you need motor reverse. I also hate driving EVs where you get the clank of contactor every time you step on the throttle or brake. That is very annoying to me.


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## jyanof (Nov 11, 2008)

I'd like to throw in my own two bits - I had my controller fail (in a non-silicon way) while backing out of a parking spot at work. There was only about a car's length between my row and the next row of cars, but my car only moved about 5 feet.

Here's my setup:


Paul&Sabrina DIY controller - actually, Paul's 2nd prototype
voltmeter after the precharge resistor, across B+/B- on the controller - essentially it displays voltage on the caps; I can watch it precharge, for example.
B+ contactor (SW200) is actuated by the switch on the throttle. Yep, clickityclack every time the pedal is pressed and released, but I think it's a small trade-off for safety (esp with a diy controller).
manual circuit breaker on B-, but this didn't come into play

I got in the car and noticed the voltmeter was essentially zero. That should've been a warning, but I continued anyway. The car lurched backwards, but instantly stopped accelerating when I instinctively pulled my foot off the pedal. The contactor had some deep pits indicating that it did its job of breaking a large amount of current.



Some would not recommend actuating the contactor like that and I'll admit it took some finesse to get working correctly. I was able to set the low point on the throttle so that the contactor closes before current is pulled from the battery. Additionally, the throttle ramp rate is set to be fairly moderate. Fortunately, when the throttle is released, the controller output drops to zero very fast and keeps the controller from draining its caps when the contactor opens. The contactor contacts were unscathed until the 'event'.

Here's a link to the details on the failure - a bolt wore through some insulation and bridged two hot parts of the controller and completed the circuit (hence, not a silicon failure). Actually, most everything was fine and a few dollars worth of parts got it working again.

Admittedly, the arcing may not have been as severe of a failure as a silicon full-on failure, but it was still pretty scary.

http://ecomodder.com/forum/showthre...44v-motor-controller-6404-372.html#post191429


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## Qer (May 7, 2008)

jyanof said:


> I got in the car and noticed the voltmeter was essentially zero. That should've been a warning, but I continued anyway.


This is exactly why I think that precharge shouldn't be the drivers responsibility but should be performed by software that won't be stressed, tired or able to think "What the hell!"...


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## jyanof (Nov 11, 2008)

Qer said:


> This is exactly why I think that precharge shouldn't be the drivers responsibility but should be performed by software that won't be stressed, tired or able to think "What the hell!"...


I'd agree with this - would be a great feature to add to the open source controller (and I think some of Paul's newest projects include it).


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## Qer (May 7, 2008)

cts_casemod said:


> Lets think solution not problem...!


Then two questions:

1. How will you avoid the contactor wearing out?

2. What are you hoping to achieve that can't be achieved in any other, potentially easier/cheaper, way?


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## EVfun (Mar 14, 2010)

The stakes are a bit different if you are running a Curtis 1231 instead of a Soliton or Zilla. The older Curtis design calls for a clacking contactor as it will not detect a runaway condition. 

I have an idea for a Curtis. How about running ignition power through a reed switch that is attached to a traction pack cable going to the controller. This switch should be located so that if more than 50 or 100 amps is flowing the magnetic field from the traction cable will turn it on. You also use the potbox microswitch contacts that are closed when the throttle is released. If power can flow through the reed switch and microswitch then it can turn on a single pole double throw relay. Ignition switched power goes to the arm of this relay and through the normally closed contact to the main contactor. If the reed switch and microswitch turn on the relay the N.C. contact looses power and the contactor opens. The N.O. contact gets power and it is connected to the relay coil, latching the relay. 

The only time the contactor should switch off when you release the throttle is if the controller is stuck on.


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## cts_casemod (Aug 23, 2012)

Qer said:


> Then two questions:
> 
> 1. How will you avoid the contactor wearing out?
> 
> 2. What are you hoping to achieve that can't be achieved in any other, potentially easier/cheaper, way?


1. Wire an opamp/comparator circuit to the output so the contactor will only open in case the output is on when you apply the brakes. The controller is supposed to kill the output when you aplly the brakes so IF and ONLY it DOESNT (In case of a fault) the circuit will open the contactor.

2. If theres an easier way, please enlighten us, I just gave an idea and explained why it should work and what was being said wrong.

Cheaper than a contactor and a PCB with a few electronic ICs?? Only a kill switch, that is already present on the car, but I am no super human to press the switch in a fraction of second before something goes bang. 

When I drive on the public roads I like to be sure my car is safe. I don't want to kill a pedestrian crossing the road because I am stopped and the controller fails moving the car forward without my input. Thats how I think.


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## cts_casemod (Aug 23, 2012)

EVfun said:


> The stakes are a bit different if you are running a Curtis 1231 instead of a Soliton or Zilla. The older Curtis design calls for a clacking contactor as it will not detect a runaway condition.
> 
> I have an idea for a Curtis. How about running ignition power through a reed switch that is attached to a traction pack cable going to the controller. This switch should be located so that if more than 50 or 100 amps is flowing the magnetic field from the traction cable will turn it on. You also use the potbox microswitch contacts that are closed when the throttle is released. If power can flow through the reed switch and microswitch then it can turn on a single pole double throw relay. Ignition switched power goes to the arm of this relay and through the normally closed contact to the main contactor. If the reed switch and microswitch turn on the relay the N.C. contact looses power and the contactor opens. The N.O. contact gets power and it is connected to the relay coil, latching the relay.
> 
> The only time the contactor should switch off when you release the throttle is if the controller is stuck on.


Excellent Idea, but don't forget that if the throttle gets stuck the contacts wont be closed, so its still prone to fail, although it should be 95% safe.

{EDIT}

I've been thinking about it and actually thats a great idea, as the brake switch could fail as well, so I believe both would be 99.95% bullet proof. Theres no way you can have a stuck throttle and a faulty brake switch at the same time! I am gonna implement your idea on my AC System.


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## palmer_md (Jul 22, 2011)

cts_casemod said:


> 2. If theres an easier way, please enlighten us, I just gave an idea and explained why it should work and what was being said wrong.


Perhaps, because the motor controller he is most familiar with has this functionality already built into the controller, he is a bit biased. If you have a controller that does not have this function built in then perhaps your efforts are warranted.


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## cts_casemod (Aug 23, 2012)

palmer_md said:


> Perhaps, because the motor controller he is most familiar with has this functionality already built into the controller, he is a bit biased. If you have a controller that does not have this function built in then perhaps your efforts are warranted.


We don't know how this is implemented. Some of them are by software and *I* wouldn't trust a software approach for such a safety feature. 

Having said this I don't mean that there are no fail proof controllers out there, but regardless you cant really test them until they fail and by then it may be too late.

There are many more non protected controllers out there that we can all imagine.


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## PStechPaul (May 1, 2012)

cts_casemod said:


> To ease the contactor life you could use an *ampop* that would only disable it in case both the brake was operated and there was an output for the motor (Read this as either you accelerate and brake at the same time or the controller switch (mosfet, transistor) had failed (shorted).
> 
> Lets think solution not problem...!


What's an ampop? Do you mean opamp? I think you really need a logic circuit or microcontroller for this, or even wired relay logic...

And I think the best safety device is a clutch. It's not really needed for an EV but you should be able to drive using it in the same way. It should last a long time because there is no need to "slip" it, and the clutch interlock could be used to open the safety interlock contactor if there was still power applied to the motor when the clutch is fully disengaged. Also the pilot bearing should see little wear because the motor should not be running when the clutch disconnects it from the transmission.


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## Duncan (Dec 8, 2008)

This is all getting a bit silly 
Like the nonsense about the Toyota throttles sticking
In any car I have ever driven the brakes can overpower the throttle - and that should be your first move!

I am using the a brake light switch to short out the throttle signal - that should eliminate one failure mode

If I did have a failure
(1) - slam on the brakes 
-- This would "zero" the throttle
(2) - hit the switch to remove power to the contactor
(3) - pull the cable to the physical disconnect

My reflexes may not be that good - but acceleration with full brakes will be low and I would expect to stop my car in a couple of feet from stationary

Controller failure when driving at speed would be hairier - but if I am close to the limit on a corner then I should be on the race track


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## Qer (May 7, 2008)

cts_casemod said:


> 1. As I said, wire an ampop to the output so the contactor will only open in case the output is on when you apply the brakes. The controller is supposed to kill the output when you aplly the brakes so IF and ONLY it DOESNT (In case of a fault) the circuit will open the contactor.


Don't forget that you have to delay that check a certain time depending on what motor you have, what driving conditions you have etc since the magnetic field in the motor will keep the current flowing for a while, which means that the contactor can't open until several tens of a second has passed. Then it takes quite some time for the magnet field in the contactor to decay enough for the contactor to open and somewhere there we're probably talking something like 0.5 seconds +/- some hundreds to be on the safe side so you won't get a lot of false positives.

Those conditions sounds like the practical way to solve it is by software, which means that you will end up having (possibly untested) software that is expected to catch an error condition that will hopefully never show up. You can do it in hardware too of course, but the same thing here; it's a bit of an untestable condition and you will rely on that when it happens the system will work flawlessly, which means that you HAVE to test it regularly since it's an active system which very well might break silently, ie you won't notice it until it fails to save your ass...

It's still probably faster than a human slamming an emergency button on the dash, but on the other hand; the emergency button WILL work AND is very simple to test, and the normal way for an emergency button to break is that it won't connect which means no power to the controller. Safe(r)...



cts_casemod said:


> When I drive on the public roads I like to be sure my car is safe. I don't want to kill a pedestrian crossing the road because I am stopped and the controller fails moving the car forward without my input. Thats how I think.


I think the amount of cars that comply with that are pretty much non-existent. Put the gear box in neutral (or turn off the ignition...) is probably the only way you can guarantee that it won't suddenly lurch forward, killing someone.

At the moment I'm working with test systems for the software in small gas engines and, guess what, there's situations when even a small engine, even without software, can cause a runaway situation and since the stop button doesn't short the high voltage side any more it could theoretically be unstoppable.

The all mechanical engines weren't 100% failsafe as well and, well, generally speaking things weren't safer in the good ol' days as well. Most of the guys working there are racing nuts (maybe not a big surprise since they develop engines) and one topic at a break was how much FEWER people die in racing these days, which is a result, direct or indirect, of how software today is used both in construction and running of todays racing cars.



cts_casemod said:


> Some of them are by software and *I* wouldn't trust a software approach for such a safety feature.


Software is great! Software makes it possible for one ordinary human to do hundreds of thousands of mistakes in less of a second! 

The software industry is still immature, like every other industry in it's youth it has to get all the kinks out, get proper routines and learn by it's mistakes. It's getting better and especially for embedded systems (like the software for Soliton or the engine mentioned above) it's pretty easy to do test systems that will make it very hard to still create potentially dangerous bugs.

A test system like that can, for example, simulate ten different ways a controller can run away. It's of course impossible to do any software 100% safe (at least today...) but you can catch most mistakes and, often even more desirable and practical, make sure a stupid mistake isn't repeated!

The problem is to introduce and get bosses etc to understand WHY these tests are necessary, especially after the often mandatory outcry from the bean counters. It's common and accepted today that every mechanical part has to be tested thoroughly, IKEA, for example, test all the furniture they make that a chair survives so and so many sittings, that a drawer survives so and so many openings and closings and so on. The engines run for HOURS in fire proof testing rooms (that of course costed a lot to construct) just to make sure there isn't any mechanical weaknesses in the product and so on and so on.

The mechanical industry is mature, everyone knows extensive testing is part of the game, the same doesn't go for the software industry. Sure, the programmers know everything has to be tested, but when you start to talk with the guys that decide over the money they have a tendency to just see the bill. You can often wing it with software, if you're lucky it goes well, if you're NOT lucky... Well... 

However, since software is getting more and more important in vehicles, the awareness is slowly emerging that PERHAPS it would be a good idea to scrutiny the software as well as the other parts that makes up an ordinary car, and thus different software safety projects and committees has started to appear, like MISRA Since it's a commodity they're prone to cause both good and bad things, and I definitely don't agree with some of the rules and ideas, but many of the things they've got right and will definitely improve software in the automotive sector.

One of the reasons we use computers and software is that they get more done faster and cheaper than any other technology, which of course means that done right they will also improve safety. Done wrong, however, there's no limit on how much problems software could potentially cause and one of the things that's GOOD with MISRA is that it makes it more or less impossible to pick a general purpose computer OS and adapt it to a car.

'cause seriously, few things in the world would scare me as much as if the market suddenly was flooded with cars that had a sticker saying "Powered by Microsoft Windows"...


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## Salty9 (Jul 13, 2009)

Qer said:


> 'cause seriously, few things in the world would scare me as much as if the market suddenly was flooded with cars that had a sticker saying "Powered by Microsoft Windows"...


That is a scary thought. Doesn't Ford say that now for some cars?


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## Ziggythewiz (May 16, 2010)

The worrying part is that Ford mails you an update for your car on a USB stick. What happens if someone malicious mails you a USB stick first?


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## Qer (May 7, 2008)

Ziggythewiz said:


> The worrying part is that Form mails you an update for your car on a USB stick. What happens if someone malicious mails you a USB stick first?


This definitely falls into the "What Could Possibly Go Wrong?"-department.

Why Windows is a bad choise in these situations:

http://en.wikipedia.org/wiki/Stuxnet

If I hadn't already decided never to buy Ford, this would be a good reason.


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## EVfun (Mar 14, 2010)

Duncan said:


> This is all getting a bit silly
> Like the nonsense about the Toyota throttles sticking
> In any car I have ever driven the brakes can overpower the throttle - and that should be your first move!
> 
> ...


Here is the catch -- in a series wound motor powered EV the brakes cannot overpower the motor unless the battery pack is weak. As the motor rpm falls the current and torque rises, all the way to the point where something breaks or a fuse blows. The fuse won't blow quickly enough to be reasonably comforting unless you can get the current to around 4x its rating. 

I've had this failure with an old Curtis 1221b controller. I was dragging the front tires while the rear tires where doing a burnout. The Albright SW200 contactor saved the day.


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## cts_casemod (Aug 23, 2012)

PStechPaul said:


> One minor point on DC motor control with a contactor is that a fast commutating diode across the motor (inductive load) will eliminate the high voltage inductive kick that can cause a large arc and contact damage. The motor's generated voltage will be less than the battery voltage, and essentially nothing for a series wound DC motor. And a snubber across the contacts will further reduce any problems. I should make a "short" video demonstrating this with an inductor and a small series wound 12V motor.
> 
> But in any case I don't think it's a good idea to open a contactor in series with the motor except in emergency failure situations. And in that case it may even be best to apply a solid short circuit across the motor which will cause immediate dynamic braking and also current sufficient to blow the battery pack fuse.


Thanks for the reminder,yes, thats an opamp, sorry my electronics school was in a different country...

I wouldn't try to short a battery pack at 96 or higher volts. I've once welded a contactor at 48VDC before the fuse blow, when I had a short at the output, I guess at 96V the arc would be even worse.


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## cts_casemod (Aug 23, 2012)

EVfun said:


> Here is the catch -- in a series wound motor powered EV the brakes cannot overpower the motor unless the battery pack is weak. As the motor rpm falls the current and torque rises, all the way to the point where something breaks or a fuse blows. The fuse won't blow quickly enough to be reasonably comforting unless you can get the current to around 4x its rating.
> 
> I've had this failure with an old Curtis 1221b controller. I was dragging the front tires while the rear tires where doing a burnout. The Albright SW200 contactor saved the day.


Thats what most fail to understand


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## PStechPaul (May 1, 2012)

Series wound = seriously scary!


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## Duncan (Dec 8, 2008)

EVfun said:


> Here is the catch -- in a series wound motor powered EV the brakes cannot overpower the motor unless the battery pack is weak. As the motor rpm falls the current and torque rises, all the way to the point where something breaks or a fuse blows. The fuse won't blow quickly enough to be reasonably comforting unless you can get the current to around 4x its rating.
> 
> I've had this failure with an old Curtis 1221b controller. I was dragging the front tires while the rear tires where doing a burnout. The Albright SW200 contactor saved the day.


This is obvious - and while doing a burnout with your front wheels dragging your acceleration was????

On most RWD cars the acceleration would be - ZERO - you would sit there for the small time it would take for you to hit the panic switch
And in my case if the contactor(s) had welded shut to pull the physical disconnect

In my case with a significant rearwards weight distribution I would accelerate - SLOWLY

FWD cars would drag their rear wheels - but again the acceleration would be very low

4WD cars - these could accelerate faster - BUT only if they had feeble brakes - and who builds a 4WD sports car with feeble brakes?

This only applies to direct drive - with a gearbox you can always drop the clutch or knock it into neutral


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## cts_casemod (Aug 23, 2012)

Duncan said:


> This only applies to direct drive - with a gearbox you can always drop the clutch or knock it into neutral


Good luck trying to get out of gear while under full power (unless you have a clutch, which most don't).


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## Duncan (Dec 8, 2008)

cts_casemod said:


> Good luck trying to get out of gear while under full power (unless you have a clutch, which most don't).


Have you ever tried?

You need to "knock" it out of gear - but a quick bash on the gearlever works

Or at least it did the only time I ever had to!


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## cts_casemod (Aug 23, 2012)

Duncan said:


> Have you ever tried?
> 
> You need to "knock" it out of gear - but a quick bash on the gearlever works
> 
> Or at least it did the only time I ever had to!


I did and once ended up having to buy a new gear linkage as it happen to be made of plastic.


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## EVfun (Mar 14, 2010)

Duncan said:


> [snip] and while doing a burnout with your front wheels dragging your acceleration was????
> 
> On most RWD cars the acceleration would be - ZERO - you would sit there for the small time it would take for you to hit the panic switch
> And in my case if the contactor(s) had welded shut to pull the physical disconnect
> ...


Well, it happened to me in reverse in a VW beach buggy (Beetle frame.) The acceleration was startling, especially those first few feet it took me to get from accelerator to brake. The rear tires where squealing and the front tires locked. Steering was limited. I planted the end bell of my Prestolite motor against the front bumper of a class A motorhome and knocked it off the built in leveling jacks. It was mentally difficult to look forward while charging backward, but once I did I could turn off the ignition switch and the Albright SW200 saved the day. Other than sacrificing an SW200 (actually, I've seen worse in service) there was no damage to my buggy.

I have no clutch and I'm pretty sure you can't knock a VW transaxle out of gear at 1000 amps. If you didn't bend the shift forks the skinny little early shifter would bent over. 

Have you seen the front tires from the White Zombie from a run where the power didn't stop at the end of the quarter mile? They each have a flat spot where the tread is worn completely gone while the rest of the tire has great tread. 

I would not challenge a series wound motor to a locked rotor contest. They almost always win by spinning anyway. When I replaced the Curtis 1221b with another one I installed a clanking main contactor, with a precharge resistor around it to keep the controller ready. Naturally, I don't need that anymore with my Zilla.


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## Duncan (Dec 8, 2008)

Hi EVFun

You make my case

*there was no damage to my buggy.*

High acceleration for the fraction of a second it took to get the brakes on - probably more for backward then forwards

Followed by creeping along until you hit your breaker

I am not going to create an accident waiting to happen by wiring my contactors to some kludge circuit just to stop an unlikely and not serious event


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## EVfun (Mar 14, 2010)

I didn't say no damage to the motorhome. I left a clear imprint of the finned end bell in the front bumper. I made nice clean contact with the front bumper and was able to move the motorhome, which must have weighed in around 18,000 lb., and had its parking brake set. The runaway condition was incredibly more powerful than the controller ever was when working.

If you have not experienced a full on failure you should not be telling others how it works out. I've experienced it. I recommend you either use a modern on-road controller designed to detect failure and shut down the main contactor (such as a Soliton or Zilla) or wire up a Curtis as the manufacturer recommends (complete with clicking contactor.) 

It got my attention good enough that I did something about it when I replaced the Curtis 1221b with another one. Initially, I used the brake light circuit to operate a relay to open the main contactor because I didn't have a pot box microswitch. When I got my microswitch I wired up the relay as a latching relay and used the pot box microswitch to break that latch (cut contactor when I first touch the brakes and re-close the main contactor when I touch the throttle.) The Curtis does not start up each time the contactor closes because it remains pre-charged and ksi remains powered. 

When I replaced my controller with a Zilla Z1k (and my battery pack with Lithium) I removed the contactor control circuit. It is no longer required as the controller handles the checking and will turn off the main contactor in a fraction of a second if the power stage locks on.


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## evnz (Jul 24, 2010)

EVfun said:


> When I replaced the Curtis 1221b with another one I installed a clanking main contactor, with a precharge resistor around it to keep the controller ready. Naturally, I don't need that anymore with my Zilla.


Precharge is done how and why...... i am looking at the Kilovac LEV200 for my killswitch on both + and - 
Thanks owen


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## Ziggythewiz (May 16, 2010)

There's several threads on precharging, here's one.


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## Tesseract (Sep 27, 2008)

evnz said:


> Precharge is done how and why...... i am looking at the Kilovac LEV200 for my killswitch on both + and -
> Thanks owen


If you are still using an Evnetics controller then you don't need to worry about precharge. Also, your service/emergency disconnect should go in series with the positive battery cable as the internal contactor(s) break the negative.


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## evnz (Jul 24, 2010)

Tesseract said:


> If you are still using an Evnetics controller then you don't need to worry about precharge. Also, your service/emergency disconnect should go in series with the positive battery cable as the internal contactor(s) break the negative.


Yes got it about 2 weeks ago and (WOW it is bigger than i had gessed) i can hardy what to get going as for contactors on both lines 
I read our ruel book (2.2 page 7) and took it that way 

this happened to steve mauck's ?
"e.g. a closing contactor with no precharge, then the current will be very high. Nearly all of the traction pack voltage will be across the closing contacts. The large Voltage difference and sudden high current (known as an inrush current) can cause damage to, and in extreme cases, welding of the relay contacts."

So if the soliton 1 has a precharge and i put a contactor on the battery line, it will have to close with the precharge load on it every time ? What sort of amps is it likely to be ?


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## Tesseract (Sep 27, 2008)

evnz said:


> ...
> this happened to steve mauck's ?
> "e.g. a closing contactor with no precharge, then the current will be very high. Nearly all of the traction pack voltage will be across the closing contacts. The large Voltage difference and sudden high current (known as an inrush current) can cause damage to, and in extreme cases, welding of the relay contacts."


Once again, you don't need to worry about precharge with an Evnetics controller, no matter how many other contactors you have to put into the battery circuit to satisfy your rules. All you need to do is make sure all of those contactors, switches, etc., are closed within 1 second of applying 12V power to the controller. In other words, full pack voltage must be present across the B+ and B- terminals of the controller within 1 second of turning it on.


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## Qer (May 7, 2008)

Tesseract said:


> Once again, you don't need to worry about precharge with an Evnetics controller, no matter how many other contactors you have to put into the battery circuit to satisfy your rules. All you need to do is make sure all of those contactors, switches, etc., are closed within 1 second of applying 12V power to the controller. In other words, full pack voltage must be present across the B+ and B- terminals of the controller within 1 second of starting turning it on.


Just to be crystal clear; the Soliton contains a complete precharge circuit including precharge resistor and contactors etc inside of it's housing. The precharge is initiated one second after 12 Volt is applied and the internal contactors aren't closed until the precharge cycle is completed. The current during the precharge cycle is very low (especially compared to the current during driving!) and thus won't be of any concern for the rest of the electronics.

There is therefore no need for any kind of external precharge circuit like for many other controllers and any attempt to add such a circuit will probably only end with the Soliton reporting an error and refusing to activate the internal contactors. To avoid the Soliton to trig an error, any external contactor(s) should get powered at the same time as the Soliton is powered to ensure that the pack voltage is present within that second after which the precharge cycle is initiated. If the pack voltage isn't present, the Soliton will abort the precharge cycle and report an error.


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## steve mauck (Aug 28, 2012)

Just a note to say that I have ordered a Soliton Jr. from EV Electrics. I expect it to be delivered today. I have ditched the old EPC 1000 controller and have noticed that Paul Z. has sold exactly zero of these on ebay the past couple of weeks. I like the fact that the Soliton will eliminate the necessity of an external contactor. I think my built will be much safer with the Soliton.


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## evnz (Jul 24, 2010)

steve mauck said:


> Just a note to say that I have ordered a Soliton Jr. from EV Electrics. I expect it to be delivered today. I have ditched the old EPC 1000 controller and have noticed that Paul Z. has sold exactly zero of these on ebay the past couple of weeks. I like the fact that the Soliton will eliminate the necessity of an external contactor. I think my built will be much safer with the Soliton.


You made a good choose just make shure you use a 3 wire accerator pot


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## cts_casemod (Aug 23, 2012)

I invite everyone to come and see my conversion. 
I will go with the AC route for reasons stated on this topic.

http://www.diyelectriccar.com/forums/showthread.php?p=321287#post321287

Feel free to comment and give some ideas.


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## dtbaker (Jan 5, 2008)

evnz said:


> You made a good choose just make shure you use a 3 wire accerator pot



with the Soliton, the Hall effect throttle is much preferred over a pot box....


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## evnz (Jul 24, 2010)

dtbaker said:


> with the Soliton, the Hall effect throttle is much preferred over a pot box....


Thats it ! Thanks I could not remember so i tryed to say it as close as i knew


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## dladd (Jun 1, 2011)

dtbaker said:


> with the Soliton, the Hall effect throttle is much preferred over a pot box....


I don't think thats true. In fact the nice looking three wire TPS that Evnetics sells for their controllers is a potentiometer.


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## Qer (May 7, 2008)

dtbaker said:


> with the Soliton, the Hall effect throttle is much preferred over a pot box....





dladd said:


> I don't think thats true. In fact the nice looking three wire TPS that Evnetics sells for their controllers is a potentiometer.


Either is good, really. We do not recommend the old style 2 wire pot box for several reasons, but the hall effect and a good quality three wire automotive potentiometer should both be fine.

Hall effect pedals seems to drift with the temperature (at least some does, not sure if all of them do) which is why the deadband parameter exist. It makes it possible to adjust the zero point for the pedal so the car doesn't start to crawl forward (like an idling ICE car with automatic gear box tend to do) when the hall sensor starts to get warm.

Automotive potentiometers (which is used in any modern ICE car) are meant to last, however they DO wear out eventually even though it will probably take decades. They're a lot less flimsy than general purpose potentiometers that is used in some pot boxes. The Evnetics throttle assembly is expensive compared to other pot boxes for a reason... 

As I said, either is fine.


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## david85 (Nov 12, 2007)

I recently switched mine from hall effect pedal assembly to a throttle body. The soliton seems to adapt perfectly to either method.

The nice thing about using a throttle body assembly on these setups is you already have an automotive grade sensor intended to stand up to the operating conditions of the real world.

- The electrical connector is weather proof,

- The sensor is vibration resistant,

- You have two throttle return springs as required by DOT regulations (in my case they are stainless steel, so its very reliable),

- Replacement TPS sensors are found readily from any automotive outlet,

- And in my case I restored the OEM accelerator pedal and cable. That gave me the factory look, and pedal weight. Its much more comfortable to drive now.


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## cts_casemod (Aug 23, 2012)

david85 said:


> I recently switched mine from hall effect pedal assembly to a throttle body. The soliton seems to adapt perfectly to either method.
> 
> The nice thing about using a throttle body assembly on these setups is you already have an automotive grade sensor intended to stand up to the operating conditions of the real world.
> 
> ...



Mine doesn't have the whole range (0 to max), how did you setup, or which throttle body have you used? Regards


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## steve mauck (Aug 28, 2012)

I bought my S-10 without the gasoline engine, with a kit that someone else had assembled. The electrical parts were all boxed up in the back of the truck. So, with the help of my son-in-law, we installed the 9" series motor and all of the compontents. Included was a Curtis 5 kilohm potentiometer packaged so that it hooks right up to the throttle cable. 

Since my Paul Zigouras EPC motor controller, that came with the kit, was a piece of junk, I replaced it with a Solitron Jr. My Curtis potentiometer works great with the Solitron Jr. I've had no trouble with it, as it works smoothly. 

The only problem I've had with the Solitron jr. is that, when the cooling fans come on, the fuse to the dc-dc converter blows. I have bought, and it was just delivered today, a 100 micro-henry choke to choke out the radio-frequency pulse that carries over from the motor controller pulses. The Solitron instructions suggests this remedy for the problem I've been having. I'm going to install the choke tomorrow and see if this solves my fuse problem.


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## david85 (Nov 12, 2007)

cts_casemod said:


> Mine doesn't have the whole range (0 to max), how did you setup, or which throttle body have you used? Regards


You'll have to plug the controller into a laptop computer using the ethernet port on the side (or PC if you can get it close enough). Once in the setup menu, the procedure is pretty self explanatory but basically you'll be maually setting the idle and WOT positions so the soliton knows where the operating range is. The owners manual will also explain how to go about it.


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## Ace_bridger (Nov 22, 2011)

dladd said:


> I don't think thats true. In fact the nice looking three wire TPS that Evnetics sells for their controllers is a potentiometer.


 
You could try a Penny & Giles hall effect TPS280DP. They have a very good reputation and that;s what I have on my Golf.


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## evnz (Jul 24, 2010)

steve mauck said:


> I bought my S-10 without the gasoline engine, with a kit that someone else had assembled. The electrical parts were all boxed up in the back of the truck. So, with the help of my son-in-law, we installed the 9" series motor and all of the compontents. Included was a Curtis 5 kilohm potentiometer packaged so that it hooks right up to the throttle cable.
> 
> Since my Paul Zigouras EPC motor controller, that came with the kit, was a piece of junk, I replaced it with a Solitron Jr. My Curtis potentiometer works great with the Solitron Jr. I've had no trouble with it, as it works smoothly.
> 
> The only problem I've had with the Solitron jr. is that, when the cooling fans come on, the fuse to the dc-dc converter blows. I have bought, and it was just delivered today, a 100 micro-henry choke to choke out the radio-frequency pulse that carries over from the motor controller pulses. The Solitron instructions suggests this remedy for the problem I've been having. I'm going to install the choke tomorrow and see if this solves my fuse problem.



Does your dc-dc run into a battery it may take out the (fuse blowing )pecks in power


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## steve mauck (Aug 28, 2012)

evnz said:


> Does your dc-dc run into a battery it may take out the (fuse blowing )pecks in power


Yes, I do have a battery along with the dc-dc converter. I can run the lights and it doesn't blow the fuse, but as soon as the fans come on, the fuse blows. Tomorrow, I'll install the toroid choke and see if that helps. I have an S-10 air conditioner small radiator that I'm ultimately going to use in a circulating water cooler for the soliton, which should eliminate the fans from running. But in the mean time, I'm hoping the toroid choke will keep the fuse from blowing. We'll see.


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