How To Burn Up Your DC Motor

classic Classic list List threaded Threaded
50 messages Options
123
Reply | Threaded
Open this post in threaded view
|

How To Burn Up Your DC Motor

Bruce Lawton
Maybe this is common knowledge for this group, but I recently learned how to burn up my motor.

I was returning home, thinking about the prospect of working on the car and bumping the accelerator. I was working under the dash recently, on the heater core. If it were in gear and on, who would win: the motor or the parking brake? Some of you see where this is headed. I parked the car in the garage, set the brake and pressed the accelerator for at least 2 seconds, probably 4 or 5 seconds. The battery delivered 25A during this. The brake won, I turned everything off and went inside. The next day, as the car began to roll, there was a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A LOT of motor amps had heated it when it wasn't turning.

The Zilla has stall protection; my Soliton apparently does not.

Lesson learned.  :-\

BTW, Steve and Audrey from Green Shed Conversions drove up from Florida on short notice and brought a spare motor so I could show the car for Earth Day. Wow! Kudos and a big thank you!

Bruce

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Mike Willmon
I'm glad my Zilla has stall detect. its kicked in a couple times pulling
onto a trailer :-)
On Apr 21, 2012 2:51 PM, "Bruce Lawton" <[hidden email]> wrote:

> Maybe this is common knowledge for this group, but I recently learned how
> to burn up my motor.
>
> I was returning home, thinking about the prospect of working on the car
> and bumping the accelerator. I was working under the dash recently, on the
> heater core. If it were in gear and on, who would win: the motor or the
> parking brake? Some of you see where this is headed. I parked the car in
> the garage, set the brake and pressed the accelerator for at least 2
> seconds, probably 4 or 5 seconds. The battery delivered 25A during this.
> The brake won, I turned everything off and went inside. The next day, as
> the car began to roll, there was a tick-tick sound. I'd overheated the
> commutators and lifted 4 bars. A LOT of motor amps had heated it when it
> wasn't turning.
>
> The Zilla has stall protection; my Soliton apparently does not.
>
> Lesson learned.  :-\
>
> BTW, Steve and Audrey from Green Shed Conversions drove up from Florida on
> short notice and brought a spare motor so I could show the car for Earth
> Day. Wow! Kudos and a big thank you!
>
> Bruce
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120421/fcde9cb9/attachment.html 
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

David Dymaxion
In reply to this post by Bruce Lawton
Bummer. Does your EV still have the tranny or are you direct drive?

BTW the parking brake went overcenter on my EV once -- I couldn't get the parking brake to release. I was able to drive it off the trailer and into my garage against the parking brake without drama. That was with 48V on my Kostov sepex, the "controller" was just a switch... No Amp limit! Since there was no PWM there was no current multiplication, though.



________________________________
 From: Bruce Lawton <[hidden email]>
To: [hidden email]
Sent: Saturday, April 21, 2012 4:50 PM
Subject: [EVDL] How To Burn Up Your DC Motor
 
Maybe this is common knowledge for this group, but I recently learned how to burn up my motor.

I was returning home, thinking about the prospect of working on the car and bumping the accelerator. I was working under the dash recently, on the heater core. If it were in gear and on, who would win: the motor or the parking brake? Some of you see where this is headed. I parked the car in the garage, set the brake and pressed the accelerator for at least 2 seconds, probably 4 or 5 seconds. The battery delivered 25A during this. The brake won, I turned everything off and went inside. The next day, as the car began to roll, there was a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A LOT of motor amps had heated it when it wasn't turning.

The Zilla has stall protection; my Soliton apparently does not.

Lesson learned.  :-\

BTW, Steve and Audrey from Green Shed Conversions drove up from Florida on short notice and brought a spare motor so I could show the car for Earth Day. Wow! Kudos and a big thank you!

Bruce

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120422/04461c89/attachment.html 
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Cor van de Water
Bruce,
Wow, that is indeed fast - are you sure it was only 2 sec that you used
full throttle? 25A from the batteries can easily turn into about 500A
motor current if the impedance of the loop controller - motor is low enough.
I have occasionally tested my EV pack by loading the motor while on parking
brake - apparently the fact that I had an AC (induction) motor saved me
because I just heard a swishing sound of a slow rotating (slipping)
magnetic field at full power, but no harm was done to the field windings
(this AC motor was also water cooled - still I did not dare to run the
test longer than half a minute at a time with cooling periods)

In your case it sounds like the brushes and especially the contact area with the comm
heated up (that is one place where there is resistance and thus voltage drop)
which managed to over-heat the comm bars due to the absence of cooling,
I take it that your motor has only an internal fan, not an external blower?

Indeed - lesson learned. I expect that the old motor is salvageable,
if needed by installing a new comm but probably by repairing the
damage that was done to the comm and rebanding it.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of David Dymaxion
Sent: Sunday, April 22, 2012 12:57 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] How To Burn Up Your DC Motor

Bummer. Does your EV still have the tranny or are you direct drive?

BTW the parking brake went overcenter on my EV once -- I couldn't get the parking brake to release. I was able to drive it off the trailer and into my garage against the parking brake without drama. That was with 48V on my Kostov sepex, the "controller" was just a switch... No Amp limit! Since there was no PWM there was no current multiplication, though.



________________________________
 From: Bruce Lawton <[hidden email]>
To: [hidden email]
Sent: Saturday, April 21, 2012 4:50 PM
Subject: [EVDL] How To Burn Up Your DC Motor
 
Maybe this is common knowledge for this group, but I recently learned how to burn up my motor.

I was returning home, thinking about the prospect of working on the car and bumping the accelerator. I was working under the dash recently, on the heater core. If it were in gear and on, who would win: the motor or the parking brake? Some of you see where this is headed. I parked the car in the garage, set the brake and pressed the accelerator for at least 2 seconds, probably 4 or 5 seconds. The battery delivered 25A during this. The brake won, I turned everything off and went inside. The next day, as the car began to roll, there was a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A LOT of motor amps had heated it when it wasn't turning.

The Zilla has stall protection; my Soliton apparently does not.

Lesson learned.  :-\

BTW, Steve and Audrey from Green Shed Conversions drove up from Florida on short notice and brought a spare motor so I could show the car for Earth Day. Wow! Kudos and a big thank you!

Bruce

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120422/04461c89/attachment.html
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Jeffrey Jenkins
In reply to this post by Bruce Lawton
Bruce Lawton wrote
... I parked the car in the garage, set the brake and pressed the accelerator for at least 2 seconds, probably 4 or 5 seconds. The battery delivered 25A during this. The brake won, I turned everything off and went inside. The next day, as the car began to roll, there was a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A LOT of motor amps had heated it when it wasn't turning.

The Zilla has stall protection; my Soliton apparently does not....
As of version 1.5.1 of the Soliton code that is correct - we do not prevent you from pushing current through the motor even when stalled.

We did contemplate adding this function at one time but did not because it has a high annoyance potential (ie - stall detect triggering while trying to drive up onto a trailer would infuriate me - I certainly wouldn't be "thanking my controller" for its overzealousness), and, frankly, we feel it is the motor manufacturer's responsibility to provide adequate specifications and warnings for their products, rather than it be entirely up to use to protect their products from abuse.

I should also point out that you are the only person I am aware of that has damaged a motor by stalling it in the 3.5 years we've been selling Soliton controllers, so I'd say this is a very rare problem. In contrast, we have destroyed 7 motors ourselves by pushing too much current through them for too long but I rather suspect that no one wants us to lower our current ratings or otherwise thermally-cripple our controllers to protect against that kind of abuse...

But if protecting against a stall seems really important to people - particularly people that already own our controllers - then we'll add it to the 1.6 release of the code.

We are about to roll out an intermediate version, 1.5.2, to correct the bug in the start button function (failing to idle the motor) and add a couple of minor functions: block throttle when signal is above calibrated range and a somewhat convoluted reverse switch function to protect against reversing the field polarity when the motor is already spinning. Coincidentally, both functions are being added because someone did something dumb with their controllers.

Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Cor van de Water
Can the stall protection be configurable,
so you have it default "off" but if someone
needs it, it can be configured "on" and that
person must take care when loading the car on
a trailer that he may instantly lose traction
and catapult backwards due to this feature?
(the safe way would be to use a winch or at least
a protection that can be ratcheted so the car
does not uncontrolledly leave the trailer...)

I deal with products being deployed in a
wide variety of environments with conflicting
needs on a daily basis, so this is one of the
escapes - keep it compatible (default = old behavior)
and allow it to be "upgraded" to the new feature...

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Jeffrey Jenkins
Sent: Monday, April 23, 2012 5:23 PM
To: [hidden email]
Subject: Re: [EVDL] How To Burn Up Your DC Motor


Bruce Lawton wrote
> ... I parked the car in the garage, set the brake and pressed the
> accelerator for at least 2 seconds, probably 4 or 5 seconds. The
> battery delivered 25A during this. The brake won, I turned everything
> off and went inside. The next day, as the car began to roll, there was

> a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A

> LOT of motor amps had heated it when it wasn't turning.
>
> The Zilla has stall protection; my Soliton apparently does not....
>

As of version 1.5.1 of the Soliton code that is correct - we do not
prevent you from pushing current through the motor even when stalled.

We did contemplate adding this function at one time but did not because
it has a high annoyance potential (ie - stall detect triggering while
trying to drive up onto a trailer would infuriate me - I certainly
wouldn't be "thanking my controller" for its overzealousness), and,
frankly, we feel it is the motor manufacturer's responsibility to
provide adequate specifications and warnings for their products, rather
than it be entirely up to use to protect their products from abuse.

I should also point out that you are the only person I am aware of that
has damaged a motor by stalling it in the 3.5 years we've been selling
Soliton controllers, so I'd say this is a very rare problem. In
contrast, we have destroyed 7 motors ourselves by pushing too much
current through them for too long but I rather suspect that no one wants
us to lower our current ratings or otherwise thermally-cripple our
controllers to protect against that kind of abuse...

But if protecting against a stall seems really important to people -
particularly people that already own our controllers - then we'll add it
to the 1.6 release of the code.

We are about to roll out an intermediate version, 1.5.2, to correct the
bug in the start button function (failing to idle the motor) and add a
couple of minor functions: block throttle when signal is above
calibrated range and a somewhat convoluted reverse switch function to
protect against reversing the field polarity when the motor is already
spinning. Coincidentally, both functions are being added because someone
did something dumb with their controllers.



--
View this message in context:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/How-To-Burn
-Up-Your-DC-Motor-tp4577309p4580199.html
Sent from the Electric Vehicle Discussion List mailing list archive at
Nabble.com.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Mark Warner
I would suggest an "override" feature that could be triggered by a
momentary switch that the operator has to push if he wants to do something
out of the norm, like drive the EV up onto a trailer. During normal
operation, there would be normal stall protection. Voila, the best of both
worlds.


On Mon, Apr 23, 2012 at 5:01 AM, Cor van de Water <[hidden email]> wrote:

> Can the stall protection be configurable,
> so you have it default "off" but if someone
> needs it, it can be configured "on" and that
> person must take care when loading the car on
> a trailer that he may instantly lose traction
> and catapult backwards due to this feature?
> (the safe way would be to use a winch or at least
> a protection that can be ratcheted so the car
> does not uncontrolledly leave the trailer...)
>
> I deal with products being deployed in a
> wide variety of environments with conflicting
> needs on a daily basis, so this is one of the
> escapes - keep it compatible (default = old behavior)
> and allow it to be "upgraded" to the new feature...
>
> Regards,
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: [hidden email]    Private: http://www.cvandewater.com
> Skype: cor_van_de_water     XoIP: +31877841130
> Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Jeffrey Jenkins
> Sent: Monday, April 23, 2012 5:23 PM
> To: [hidden email]
> Subject: Re: [EVDL] How To Burn Up Your DC Motor
>
>
> Bruce Lawton wrote
> > ... I parked the car in the garage, set the brake and pressed the
> > accelerator for at least 2 seconds, probably 4 or 5 seconds. The
> > battery delivered 25A during this. The brake won, I turned everything
> > off and went inside. The next day, as the car began to roll, there was
>
> > a tick-tick sound. I'd overheated the commutators and lifted 4 bars. A
>
> > LOT of motor amps had heated it when it wasn't turning.
> >
> > The Zilla has stall protection; my Soliton apparently does not....
> >
>
> As of version 1.5.1 of the Soliton code that is correct - we do not
> prevent you from pushing current through the motor even when stalled.
>
> We did contemplate adding this function at one time but did not because
> it has a high annoyance potential (ie - stall detect triggering while
> trying to drive up onto a trailer would infuriate me - I certainly
> wouldn't be "thanking my controller" for its overzealousness), and,
> frankly, we feel it is the motor manufacturer's responsibility to
> provide adequate specifications and warnings for their products, rather
> than it be entirely up to use to protect their products from abuse.
>
> I should also point out that you are the only person I am aware of that
> has damaged a motor by stalling it in the 3.5 years we've been selling
> Soliton controllers, so I'd say this is a very rare problem. In
> contrast, we have destroyed 7 motors ourselves by pushing too much
> current through them for too long but I rather suspect that no one wants
> us to lower our current ratings or otherwise thermally-cripple our
> controllers to protect against that kind of abuse...
>
> But if protecting against a stall seems really important to people -
> particularly people that already own our controllers - then we'll add it
> to the 1.6 release of the code.
>
> We are about to roll out an intermediate version, 1.5.2, to correct the
> bug in the start button function (failing to idle the motor) and add a
> couple of minor functions: block throttle when signal is above
> calibrated range and a somewhat convoluted reverse switch function to
> protect against reversing the field polarity when the motor is already
> spinning. Coincidentally, both functions are being added because someone
> did something dumb with their controllers.
>
>
>
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/How-To-Burn
> -Up-Your-DC-Motor-tp4577309p4580199.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120423/8e37ffdc/attachment.html 
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Jeffrey Jenkins
Mark Warner wrote
I would suggest an "override" feature that could be triggered by a
momentary switch that the operator has to push if he wants to do something
out of the norm, like drive the EV up onto a trailer. During normal
operation, there would be normal stall protection. Voila, the best of both
worlds.
This isn't practical because the owner would have to 1) foresee the need to override stall detection in the first place; 2) install a switch to do so; 3) remember to use the switch when the motor is inadvertently stalled!

Also, this still wouldn't have protected the OP from damaging his motor, as he *intentionally* stalled it.




Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Peri Hartman
In reply to this post by Mark Warner
The Leaf seems to have a bit of this problem.  If parallel parking on a
hill, and you're using the brake, I think it's ignoring the accelerator
pedal till you take you foot off the brake.  This results in a small surge
causing a small bump into the vehicle in front (or back).  Not sure of the
best way to solve this, but something to think about.

Peri

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Mark Warner
Sent: 23 April, 2012 7:02 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] How To Burn Up Your DC Motor

I would suggest an "override" feature that could be triggered by a momentary
switch that the operator has to push if he wants to do something out of the
norm, like drive the EV up onto a trailer. During normal operation, there
would be normal stall protection. Voila, the best of both worlds.


On Mon, Apr 23, 2012 at 5:01 AM, Cor van de Water <[hidden email]> wrote:

> Can the stall protection be configurable, so you have it default "off"
> but if someone needs it, it can be configured "on" and that person
> must take care when loading the car on a trailer that he may instantly
> lose traction and catapult backwards due to this feature?
> (the safe way would be to use a winch or at least a protection that
> can be ratcheted so the car does not uncontrolledly leave the
> trailer...)
>
> I deal with products being deployed in a wide variety of environments
> with conflicting needs on a daily basis, so this is one of the escapes
> - keep it compatible (default = old behavior) and allow it to be
> "upgraded" to the new feature...
>
> Regards,
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: [hidden email]    Private: http://www.cvandewater.com
> Skype: cor_van_de_water     XoIP: +31877841130
> Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Jeffrey Jenkins
> Sent: Monday, April 23, 2012 5:23 PM
> To: [hidden email]
> Subject: Re: [EVDL] How To Burn Up Your DC Motor
>
>
> Bruce Lawton wrote
> > ... I parked the car in the garage, set the brake and pressed the
> > accelerator for at least 2 seconds, probably 4 or 5 seconds. The
> > battery delivered 25A during this. The brake won, I turned
> > everything off and went inside. The next day, as the car began to
> > roll, there was
>
> > a tick-tick sound. I'd overheated the commutators and lifted 4 bars.
> > A
>
> > LOT of motor amps had heated it when it wasn't turning.
> >
> > The Zilla has stall protection; my Soliton apparently does not....
> >
>
> As of version 1.5.1 of the Soliton code that is correct - we do not
> prevent you from pushing current through the motor even when stalled.
>
> We did contemplate adding this function at one time but did not
> because it has a high annoyance potential (ie - stall detect
> triggering while trying to drive up onto a trailer would infuriate me
> - I certainly wouldn't be "thanking my controller" for its
> overzealousness), and, frankly, we feel it is the motor manufacturer's
> responsibility to provide adequate specifications and warnings for
> their products, rather than it be entirely up to use to protect their
products from abuse.

>
> I should also point out that you are the only person I am aware of
> that has damaged a motor by stalling it in the 3.5 years we've been
> selling Soliton controllers, so I'd say this is a very rare problem.
> In contrast, we have destroyed 7 motors ourselves by pushing too much
> current through them for too long but I rather suspect that no one
> wants us to lower our current ratings or otherwise thermally-cripple
> our controllers to protect against that kind of abuse...
>
> But if protecting against a stall seems really important to people -
> particularly people that already own our controllers - then we'll add
> it to the 1.6 release of the code.
>
> We are about to roll out an intermediate version, 1.5.2, to correct
> the bug in the start button function (failing to idle the motor) and
> add a couple of minor functions: block throttle when signal is above
> calibrated range and a somewhat convoluted reverse switch function to
> protect against reversing the field polarity when the motor is already
> spinning. Coincidentally, both functions are being added because
> someone did something dumb with their controllers.
>
>
>
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/How-To-Bu
> rn -Up-Your-DC-Motor-tp4577309p4580199.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.sjsu.edu/mailman/private/ev/attachments/20120423/8e37ffdc/attac
hment.html
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev



_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Roger Stockton
In reply to this post by Jeffrey Jenkins
Jeffrey Jenkins wrote:

> This isn't practical because the owner would have to
> 1) foresee the need to override stall detection in the first place;
> 2) install a switch to do so;

It seems these could be handled by an appropriate section in the controller owner's/installation manual.

> 3) remember to use the switch when the motor is inadvertently stalled!

The suggestion was that stall protection is active by default and the switch/button is an override to temporarily defeat it.  It seems to me that if I had read the manual and installed the switch, that I would probably remember it reasonably soon after the stall protection interfered with my loading or unloading my EV from the trailer ;^>

It is the converse that is an issue: i.e. only motor damage will remind the user to turn off the switch should they neglect to re-enable stall protection.

Some SW intelligence could certainly help here, for instance rather than considering the open or closed position as enabling or disabling stall protection, instead consider a transition between the two states as disabling the protection for a short time.  At the very least, the SW should re-enable the protection after a fixed amount of time, regardless of the switch position, and perhaps indicate a warning.

> Also, this still wouldn't have protected the OP from damaging his motor,
> as he *intentionally* stalled it.

True, but is there really anything you can do to protect the motor from intentional abuse?

Cheers,

Roger.


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Lee Hart
In reply to this post by Cor van de Water
On 4/23/2012 7:01 AM, Cor van de Water wrote:
> Can the stall protection be configurable,
> so you have it default "off" but if someone
> needs it, it can be configured "on"

I think that would ba good plan.

To avoid having it suddenly cut all power, it could be configured like
an RPM limiter or current limiter, which back off the power gradually
rather than suddenly cut out completely.

The main reason for a stall limiter is to stop ignorant drivers from
attempting to hold the car motionless on a hill (at a stop light, for
instance). I know quite a few motors have been murdered that way!

--
Opportunity is missed by most people because it is dressed in overalls
and looks like work. -- Thomas A. Edison
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Lee Hart
In reply to this post by Mark Warner
On 4/23/2012 9:02 AM, Mark Warner wrote:
> I would suggest an "override" feature that could be triggered by a
> momentary switch that the operator has to push if he wants to do something
> out of the norm, like drive the EV up onto a trailer. During normal
> operation, there would be normal stall protection. Voila, the best of both
> worlds.

It's also important to note that the motor fails because it is
completely motionless. If one comm bar sits right under the brush for
many seconds at high current, it overheats.

A movement of even one comm bar per second is enough to prevent this
failure. There won't be a problem from creeping onto a trailer. But
there *will* be from holding the car motionless with the parking brake,
or holding the car on a hill for 30 seconds until the light turns green! :-O

--
Ingenuity gets you through times of no money better than money
will get you through times of no ingenuity. -- Terry Pratchett
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Lee Hart
In reply to this post by Peri Hartman
On 4/23/2012 9:48 AM, Peri Hartman wrote:
> The Leaf seems to have a bit of this problem.  If parallel parking on a
> hill, and you're using the brake, I think it's ignoring the accelerator
> pedal till you take you foot off the brake.  This results in a small surge
> causing a small bump into the vehicle in front (or back).  Not sure of the
> best way to solve this, but something to think about.

Burnout at stall is less of a problem with an AC motor. In a DC motor,
the commutator bar is what overheats and fails. It is physically so
small that this can occur in seconds at high currents.

In an PM AC motor at stall, one winding and one transistor (of the 6 in
a 3-phase inverter) is getting all the current. These too can fail, but
they are physically much bigger so will take longer for them to overheat.

In an AC induction motor, there is no particular problem at stall. The
rotor will get terrifically hot at stall, but it is pretty massive and
can stand it for minutes on end.

The worst case for an induction motor is if it being forced to rotate
backward while the controller is commanding forward. If the reverse
speed is exactly the slip speed, the phase windings are again stopped so
all the current is applied to one winding and one transistor, and you
have the same problem as the PM AC motor. However, it's pretty unlikely
you would stumble into this situation.

All these problems, for all types of motors, can (and should) be handled
by the controller.
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!    -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Jeffrey Jenkins
In reply to this post by Lee Hart
Lee Hart wrote
...
To avoid having it suddenly cut all power, it could be configured like
an RPM limiter or current limiter, which back off the power gradually
rather than suddenly cut out completely.
Great idea... but how much current should I allow through the motor when it is stalled? And how much time should I let pass between tach pulses before activating the stall detection function in the first place? What about if the commutator is already hot? What about different size motors - surely a big GE 11" can take more stall current than a little 6.7 incher?!

Etc. and so on.




Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Morgan LaMoore
It seems like some reasonable percentage (15-25%?) of your motor
current limit would be a good stall current, or else add that as a
configurable value: "Stall current limit" next to the stall detect
enable checkbox.

The time between tach pulses probably won't be too critical - if a
brush covers 3 comm bars, one comm bar overheats in two seconds and
the motor had 37 comm bars, then even three RPMs (one rotation in 24.6
seconds) would be sufficient to prevent stall failure. But since you
can't reasonably measure three RPMs fast enough to protect the
commutator, one pulse per second would give you fast enough response
and limit "nuisance trips" to only be possible below 30 RPMs (if you
have two pulses per rotation).

I don't think you need special code to handle an already hot
commutator: you don't reduce the drive current limit for a hot
commutator either. That would fall under your examples of
over-limiting it and causing problems.

I'm not one of your customers; I'm just brainstorming what controller
behavior would be a decent compromise between reasonable effort to
implement, protecting the motor, and avoiding nuisance trips.

-Morgan LaMoore

On Mon, Apr 23, 2012 at 12:56 PM, Jeffrey Jenkins
<[hidden email]> wrote:

>
> Lee Hart wrote
>>
>> ...
>> To avoid having it suddenly cut all power, it could be configured like
>> an RPM limiter or current limiter, which back off the power gradually
>> rather than suddenly cut out completely.
>>
>
> Great idea... but how much current should I allow through the motor when it
> is stalled? And how much time should I let pass between tach pulses before
> activating the stall detection function in the first place? What about if
> the commutator is already hot? What about different size motors - surely a
> big GE 11" can take more stall current than a little 6.7 incher?!
>
> Etc. and so on.
>
>
>
>
>
>
> --
> View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/How-To-Burn-Up-Your-DC-Motor-tp4577309p4581224.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Cor van de Water
In reply to this post by Peri Hartman
Peri Hartman said:
> The Leaf seems to have a bit of this problem.
> If parallel parking on a hill, and you're using the brake,
> I think it's ignoring the accelerator pedal till you take
> you [sic] foot off the brake.  This results in a small
> surge causing a small bump into the vehicle in front
> (or back).  Not sure of the best way to solve this,
> but something to think about.

Hi Peri,
I doubt that this is a stall detect feature, it sounds to
me like they made sure to never get the problem that Toyota
struggled to dismiss - the unintended acceleration.
This problem cannot occur if the brake overrides the
accelerator, which is what I see in your description.
This was actually already present on the Prius (you could
hit both accelerator and brake, though there was some effect,
the engine would still rev up higher at standstill, which can
be (mis-)used to fast-charge the battery pack.

When I made a short trip in a Leaf thanks to a local owner
who let me, I forgot to check if it has a hand (parking) brake
because that is the usual way to manage movements on an incline
so you do not need to move your foot between throttle and brake
(or worse - drive with 2 feet).
There was a reason that my driving instructor referred to those
two pedals as "water and fire".

Another observation - parallel parking, if performed with
enough space between two other vehicles, can be done in
one single movement, so you do not need to alternate
between acceleration and brake, unless there is limited space
and you need to make it a 2-point manouvre, then I was taught
to use the hand (or parking) brake on an incline, which should
avoid the accelerator override - though I did not test it.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Peri Hartman
Yes, one could use the parking brake - it is strictly physical brakes.  I
haven't tried it for parking and my foot is plenty fast enough on hills not
to need it.  

The reason I haven't tried the parking brake for parallel parking is that it
is controlled by a servo, not by a lever.  So you cannot feel when it is
engaging or disengaging.  Thus, and I may be wrong, it seems it would be
hard to know how much and when to push the accelerator.  I'll try it and
see.

Parking is tight in the city, so one movement parking is usually not
possible.  Sometimes it takes 4 or 5 times back and forth.  Don't always
have to park on a 20% grade, though.

Peri

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Cor van de Water
Sent: 23 April, 2012 12:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] How To Burn Up Your DC Motor

Peri Hartman said:
> The Leaf seems to have a bit of this problem.
> If parallel parking on a hill, and you're using the brake, I think
> it's ignoring the accelerator pedal till you take you [sic] foot off
> the brake.  This results in a small surge causing a small bump into
> the vehicle in front (or back).  Not sure of the best way to solve
> this, but something to think about.

Hi Peri,
I doubt that this is a stall detect feature, it sounds to me like they made
sure to never get the problem that Toyota struggled to dismiss - the
unintended acceleration.
This problem cannot occur if the brake overrides the accelerator, which is
what I see in your description.
This was actually already present on the Prius (you could hit both
accelerator and brake, though there was some effect, the engine would still
rev up higher at standstill, which can be (mis-)used to fast-charge the
battery pack.

When I made a short trip in a Leaf thanks to a local owner who let me, I
forgot to check if it has a hand (parking) brake because that is the usual
way to manage movements on an incline so you do not need to move your foot
between throttle and brake (or worse - drive with 2 feet).
There was a reason that my driving instructor referred to those two pedals
as "water and fire".

Another observation - parallel parking, if performed with enough space
between two other vehicles, can be done in one single movement, so you do
not need to alternate between acceleration and brake, unless there is
limited space and you need to make it a 2-point manouvre, then I was taught
to use the hand (or parking) brake on an incline, which should avoid the
accelerator override - though I did not test it.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev



_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Lee Hart
In reply to this post by Jeffrey Jenkins
On 4/23/2012 12:56 PM, Jeffrey Jenkins wrote:
Lee Hart wrote
>> To avoid having it suddenly cut all power, it could be configured like
>> an RPM limiter or current limiter, which back off the power gradually
>> rather than suddenly cut out completely.

> Great idea... but how much current should I allow through the motor when it
> is stalled? And how much time should I let pass between tach pulses before
> activating the stall detection function in the first place? What about if
> the commutator is already hot? What about different size motors - surely a
> big GE 11" can take more stall current than a little 6.7 incher?!

The perfect is the enemy of the good. You'll do nothing if you try for
perfection. Aim for good instead. :-)

As a first try: Assume the RPM sensor produces something like 4-8 pulses
per revolution, and your current limit is set to 1000a. When you apply
current to the motor, if there are no RPM pulses for 1 second, start
ramping down the current limit. Ramp it down 100a every 0.1 second, so
at 1.9 seconds it will be down to 100a current limit.

If the motor moves and you see a pulse, then increase the current limit
20% (100a + 20% = 120a) and hold it there for another second before you
start ramping it down again.

A 4 pulse/rev RPM sensor that pulses 1 per second thus gives you the
full 1000a current at 1 second/pulse (4 sec/revolution = 15 RPM), half
current at 1.1 seconds/pulse (14 RPM), and 100a current at stall (0
RPM), and smoothly transition between them.

--
*BE* the change that you wish to see in the world.
        -- Mahatma Gandhi
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Jeffrey Jenkins
Lee Hart wrote
The perfect is the enemy of the good. You'll do nothing if you try for
perfection. Aim for good instead. :-)
I admit I'm often guilty of that. In this case, though, I'm mainly trying to avoid instilling a *false* sense of security. I distinctly remember George Hamstra telling me that "hill holding" was really hard on the motor, but I only vaguely remember any numbers (this conversation took place over 4 years ago).

Lee Hart wrote
As a first try: Assume the RPM sensor produces something like 4-8 pulses
per revolution, and your current limit is set to 1000a. When you apply
current to the motor, if there are no RPM pulses for 1 second, start
ramping down the current limit. Ramp it down 100a every 0.1 second, so
at 1.9 seconds it will be down to 100a current limit.
Sounds reasonable for a WarP-9. I think it might be dangerous to extrapolate too far afield, though. For example, a Kostov 9" motor certainly can't take 1000A for 1 second when stalled. A GE 13", however, might just be able to take the full 3000A output of a Soliton Shiva before the comm explodes. All I know for sure is that obtaining good data on this is *expensive*.

I appreciate the suggestion all the same. I'll give it some (unpaid) thought and see if I can come up with a way around the various issues. That said, adding Yet Another Warning to the Fine Manual might be in order.



Reply | Threaded
Open this post in threaded view
|

Re: How To Burn Up Your DC Motor

Lee Hart
On 4/23/2012 4:55 PM, Jeffrey Jenkins wrote:
> Lee Hart wrote... As a first try...

> Sounds reasonable for a WarP-9. I think it might be dangerous to extrapolate
> too far afield, though. For example, a Kostov 9" motor certainly can't take
> 1000A for 1 second when stalled. A GE 13", however, might just be able to
> take the full 3000A output of a Soliton Shiva before the comm explodes. All
> I know for sure is that obtaining good data on this is *expensive*.

I agree that a Kostov isn't likely to survive 1000a at stall for second.
But then, it wouldn't survive 1000a running, either. The user has to set
his current limit to a value reasonable for the motor he's running.

This is all about protecting the comm bars. You could get a rough idea
of how much current and for how long by looking at the physical size of
the comm bars in each motor.

> I appreciate the suggestion all the same. I'll give it some (unpaid) thought
> and see if I can come up with a way around the various issues. That said,
> adding Yet Another Warning to the Fine Manual might be in order.

Definitely in order. People are too used to cars with automatic
transmissions. It is common practice for people to hold the car on a
hill with the engine. Unless told not to do it, they will try it on
their EV (with bad results)!
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!    -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
123