# [EVDL] EV failure mode old school.



## EVDL List (Jul 27, 2007)

The problem with PWM controllers (EVen the amazing Zilla) is they fail on full power. There are many more safeguards with the Zilla and I never heard of one going south. However the basic: Curtis, Altrax, Logisystems, Kelly, PWM, chopper etc... needs a fuse, breaker & contactor. Minimum. The key will do nothing once the contactor(s) fuse. So in my run away I keyed off. Nothing. Brake not enough. Should have blown the fuse. Fuse didn't blow. I didn't want to grenade my motor at 144vdc so I threw it in neutral and hit the breaker. That did it. I did that(in hindsight)to take the amps off the connections. I'm still going to add an Anderson connector with 2/0 wire and a handle somewhere. It will be on my Chopper MC conversion. I just don't trust contactors. Lawrence Rhodes

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## EVDL List (Jul 27, 2007)

> The problem with PWM controllers (EVen the amazing Zilla) is they fail on
> full power.


This is not always true, at least for some designs or failure modes. In
three separate tests with severe temperature and load overstressing of the
WarP-Drive, the failure mode of the power section was immediately off (BTW,
these were tests that deviated substantially from normal road stress
conditions).

The key will do nothing once the contactor(s) fuse.


I think the important question here is, why did the contactor fuse? Was the
contactor already damaged? Was it simply under-rated? Was there any
redundancy in the system?


> Brake not enough.


Everyone should understand that the brake is *not* enough to stop a full-on
condition!


> Should have blown the fuse. Fuse didn't blow.


I imagine the fuse did just what it's spec sheet said it would do - took a
certain load for a given length of time.

I didn't want to grenade my motor at 144vdc so I threw it in neutral and hit
> the breaker. That did it. I did that(in hindsight)to take the amps off the
> connections. I'm still going to add an Anderson connector with 2/0 wire and
> a handle somewhere. It will be on my Chopper MC conversion. I just don't
> trust contactors.


I think the more redundancy you can have, the better. Better overkill than
to not have enough. But, I also feel that proper selection of contactors,
and a regular service schedule that includes inspection of the contactors,
can go a long way towards a safe vehicle! The contactor(s) *should*
absolutely be capable of breaking the potential loads in the system. I
believe that for most conversions, having a mechanical disconnect of the
driveline is also very important (usually the clutch).

-Ryan
-- 
NetGain Controls, Inc.
695 W 1725 N
Logan, UT 84321
[email protected] <[email protected]>
435-705-5100
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## EVDL List (Jul 27, 2007)

In a full on failure, does that mean that here is zero pulsing in the
controller to motor cables?
Or at least substantially less then normal?

If so, it seems that an idiot light circuit could be built that would
light up when this kind of failure occurs. This circuit could
disengage the contactors to force a full on failure into a full off
failure.

This seems too easy, so I'm betting there is a gotcha, like some
normal operating mode that would exhibit the same symptom.
If there is no gotcha, I'd like to add such a circuit to my
motorcycle. The prospect of a full on motorcycle is frightening.
I've got a large circuit breaker switch in easy reach near my knee,
but I'd like to also have an automatic system that would beat me to
it.

Mike-



> NGC Sales <[email protected].xxx> wrote:
> >> The problem with PWM controllers (EVen the amazing Zilla) is they fail on
> >> full power.
> >
> ...


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## EVDL List (Jul 27, 2007)

If I was on a bike that was locked at full throttle, taking my hand
off the handlebars to reach down near my knee might be as scary as
hanging on for the ride. Better to keep the clutch in service. Or use
the clutch lever to flip the breaker.

DAC



> Mike Shipway <[email protected]> wrote:
> > In a full on failure, does that mean that here is zero pulsing in the
> > controller to motor cables?
> > Or at least substantially less then normal?
> ...


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## EVDL List (Jul 27, 2007)

The Zilla does exactly this. Every so many full cycles the Zilla actually
drops power to the power stage and looks for the voltage on the output
terminals to drop to zero. It is a very short check and as a result you are
never actually at 100% duty cycle (more like 99.99%). But this is a
periodic and frequent test the Zilla does to check for a full on failure
condition. The result is that the power section driver is turned off (in
the event the fault clears) and the main contactor is opened up.

I know this feature works. I have had it happen multiple times though
didn't actually have a full on controller failure. I had a motor arcing
event in the Pinto that caused a condition that would make the Zilla fail
this test. I can tell you from a dead stop, even with 1500 ft-lbs of launch
torque, the Pinto would launch and with wheels in the air it would shut
down. The car would coast all of about 20 ft. Many of you who were at the
Wayland Invite last summer witnessed many of such shut downs ;-)

Even still, we still run the "oh sheisse" bar just in case.... old school
style.

Mike

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Mike Shipway
Sent: Thursday, February 25, 2010 5:46 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] EV failure mode old school.

In a full on failure, does that mean that here is zero pulsing in the
controller to motor cables?
Or at least substantially less then normal?

If so, it seems that an idiot light circuit could be built that would
light up when this kind of failure occurs. This circuit could
disengage the contactors to force a full on failure into a full off
failure.

This seems too easy, so I'm betting there is a gotcha, like some
normal operating mode that would exhibit the same symptom.
If there is no gotcha, I'd like to add such a circuit to my
motorcycle. The prospect of a full on motorcycle is frightening.
I've got a large circuit breaker switch in easy reach near my knee,
but I'd like to also have an automatic system that would beat me to
it.

Mike-



> NGC Sales <[email protected]> wrote:
> >> The problem with PWM controllers (EVen the amazing Zilla) is they fail on
> >> full power.
> >
> ...


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## EVDL List (Jul 27, 2007)

> dave cover wrote:
> 
> > If I was on a bike that was locked at full throttle, taking my hand
> > off the handlebars to reach down near my knee might be as scary as
> ...


----------



## EVDL List (Jul 27, 2007)

Hi,

Not sure about legislation is the USA, but in AU, for an EV to be
registered, on top of meeting the Australian Design Rules (which all
vehicles must meet) EVs must also meet very specific standards as outlined
in NCOP14, one of which is in regards to disconnection of power to the
motor:

NCOP14 - 2.6:
A master switch for isolating the power supply to the motor and its control
apparatus must be located within easy reach of the driver. The master switch
must isolate all electrical connections to the power source. It must be
operable by direct mechanical action and must not rely on any electrical or
electromechanical device.

Something like this could be implemented quite easily to ensure any "locked
on" events were quickly stopped. As above, a mechanical connection that fips
a breaker would be ideal - then you should be able to coast to a stop quite
safely.

Leslie





> dave cover <[email protected]> wrote:
> 
> > If I was on a bike that was locked at full throttle, taking my hand
> > off the handlebars to reach down near my knee might be as scary as
> ...


----------



## EVDL List (Jul 27, 2007)

Yes NEDRA requires these as well to be able to race, NHRA actually adopted
the NEDRA safety rules so you absolutely need to have these features to race
on an NHRA track. And for the bike guy doing drag racing you need to have a
lanyard attached to the driver that does this same disconnect. I suppose in
an emergency you could tug on the lanyard to do an emergency shut down to.

Mike

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of WRX STI
Sent: Thursday, February 25, 2010 6:22 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] EV failure mode old school.

Hi,

Not sure about legislation is the USA, but in AU, for an EV to be
registered, on top of meeting the Australian Design Rules (which all
vehicles must meet) EVs must also meet very specific standards as outlined
in NCOP14, one of which is in regards to disconnection of power to the
motor:

NCOP14 - 2.6:
A master switch for isolating the power supply to the motor and its control
apparatus must be located within easy reach of the driver. The master switch
must isolate all electrical connections to the power source. It must be
operable by direct mechanical action and must not rely on any electrical or
electromechanical device.

Something like this could be implemented quite easily to ensure any "locked
on" events were quickly stopped. As above, a mechanical connection that fips
a breaker would be ideal - then you should be able to coast to a stop quite
safely.

Leslie





> dave cover <[email protected]> wrote:
> 
> > If I was on a bike that was locked at full throttle, taking my hand
> > off the handlebars to reach down near my knee might be as scary as
> ...


----------



## EVDL List (Jul 27, 2007)

What breaker are you using?

-Thor

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Roger Heuckeroth
Sent: Thursday, February 25, 2010 9:22 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] EV failure mode old school.




> dave cover wrote:
> 
> > If I was on a bike that was locked at full throttle, taking my hand
> > off the handlebars to reach down near my knee might be as scary as
> ...


----------



## EVDL List (Jul 27, 2007)

Its a two pole 400 A Seimens Sentron Series. Rated at 250V DC. Got 
it on Ebay for $40. New its over $500



> Thor Johnson wrote:
> 
> > What breaker are you using?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

>
>> > The problem with PWM controllers (EVen the amazing Zilla) is they fail on
>> > full power.
>> 
>
>
> This is not always true, at least for some designs or failure modes. In
> three separate tests with severe temperature and load overstressing of the
> WarP-Drive, the failure mode of the power section was immediately off (BTW,
> these were tests that deviated substantially from normal road stress
> conditions).
> 

Could you give some details on this? How did you over come the fact that
the switching element is in series with the motor and generally fail
shorted.**
When we say tend to fail full on, I believe we are talking about the
failure mode of the switching stage not the control put on it.

In a dc-dc that fails the controller becomes irrelevent. A shorted power
stage is full on.
We recognize in a 3 phase AC controller that the short can also happen,
but that the failure mode is partial rotor lock or loss of power. It
takes an active controller to create a runnaway condition.

And in both cases if we command it to full throttle with our foot or
otherwise, The control can't know the difference, it does it's job.

**Surly you didn't put in a 1000A crowbar circuit that is normally
shorted and is disabled prior to startup?



> The key will do nothing once the contactor(s) fuse.
>
>
> I think the important question here is, why did the contactor fuse? Was the
> contactor already damaged? Was it simply under-rated? Was there any
> redundancy in the system?
>
>
> 
>> > Brake not enough.
>> 
>
>
> Everyone should understand that the brake is *not* enough to stop a full-on
> condition!
>
>
> 
>> > Should have blown the fuse. Fuse didn't blow.
>> 
>
>
> I imagine the fuse did just what it's spec sheet said it would do - took a
> certain load for a given length of time.
>
> I didn't want to grenade my motor at 144vdc so I threw it in neutral and hit
> 
>> > the breaker. That did it. I did that(in hindsight)to take the amps off the
>> > connections. I'm still going to add an Anderson connector with 2/0 wire and
>> > a handle somewhere. It will be on my Chopper MC conversion. I just don't
>> > trust contactors.
>> 
>
>
> I think the more redundancy you can have, the better. Better overkill than
> to not have enough. But, I also feel that proper selection of contactors,
> and a regular service schedule that includes inspection of the contactors,
> can go a long way towards a safe vehicle! The contactor(s) *should*
> absolutely be capable of breaking the potential loads in the system. I
> believe that for most conversions, having a mechanical disconnect of the
> driveline is also very important (usually the clutch).
>
> -Ryan
> -- NetGain Controls, Inc. 695 W 1725 N Logan, UT 84321
> [email protected] <[email protected]> 435-705-5100 --------------
> next part -------------- An HTML attachment was scrubbed... URL:
> http://lists.sjsu.edu/mailman/private/ev/attachments/20100225/7c741b4b/attachment.html
>

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## EVDL List (Jul 27, 2007)

Maybe reversing the logic would be better. Don't rely on the presence of
12V to fire the solenoid?
Spring load the breaker release actuator and the panic button
mechanically releases the breaker actuator

or...
I believe this was mentioned before, the crowbar circuit. (search archives):
After pack fuse (or breaker) a contactor to ground that is normally
closed and energized open thus removing the short to ground when you
turn on the key.
If you turn off the key it shorts to ground be default. No problem 99%
of the time, you turn off the key when foot is off gas and main is off
so not cap drain from controller.
But on that day when you have to turn off the key while under power,
it takes out the fuse or pops the breaker.

Of course the other method of increasing the safety would just be to use
dual main contactors. one in the positive line and one in the negative.
if each switch then has a 1 in a 1000 chance of getting stuck on you now
have 1 in 1000*1000 or 1 in a million chance of both of them. (This only
works if you actually monitor the switches and notify or disable system
when one gets stuck on) I believe the Zilla performs a check on the
main contactor, but only assumes 1 contactor. One could devise a way to
prevent main start if either of the contactors is stuck on and light a
dash light instead.

The other point on the AC system I forgot to make was that it usually
requires 2 switching elements to short to make a circuit that will
result in a locking effect and not just a loss of power. Hey, the 2
switches in series trick 

>


> dave cover wrote:
> >
> >> If I was on a bike that was locked at full throttle, taking my hand
> >> off the handlebars to reach down near my knee might be as scary as
> ...


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## EVDL List (Jul 27, 2007)

I had originally intended to connect the clutch cable to the breaker handle.
I put a bungee on the end while I was testing other things, and found
that my reflex was to pull the clutch lever every time I applied the
brakes. This would latch my power off at each stop sign or in jerky
traffic. Not good.

I may still have it interrupt the 12 volts to the main contactor's coil.

Mike-



> dave cover <[email protected]> wrote:
> > If I was on a bike that was locked at full throttle, taking my hand
> > off the handlebars to reach down near my knee might be as scary as
> > hanging on for the ride. Better to keep the clutch in service. Or use
> ...


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