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Discussion Starter #1
I am in the process of building my first EV. I will have 72V and will be
using an Altrax 7245 controller and as such will pull up to 450 amps. As I
am laying out the system it seems prudent to install an emergency cutoff or
a contactor just in case there is a failure and I end up with a runaway
electric motor.



Do you think this is prudent to design in or do most EV'ers go "naked" so to
speak with no emergency cut out? If you do have an emergency cut off do
most use a manual kill switch or contactor? It looks like a contactor will
be a lot easier to design in.



Thank you



David J. Hrivnak

<http://www.hrivnak.com> www.hrivnak.com

Personal Account WWJD?



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Discussion Starter #2
Hello David,

There should be a main contactor which is normally on one side of the
battery pack power lead that is control by ignition switch. As a back up to
the ignition switch circuit that controls the main contactor and controller
circuit, I have the ignition switch back up with two more on console kill
switches.

Some motor controllers require a 12 volt ignition and 12 volt power control.
I also have a big red flag 12 volt shut down switch that kills the main 12
volt power.

For maximum safety, there should be two more contactors to kill the negative
and positive side of the battery pack. These are also control by two more
console switches and all three contactors are also control by ignition
switch and back up ignition switches.

These battery contactors are known as safety contactors, and they provide
isolation from the battery charger voltage, that may be higher than the
controller rating. Also, in some controllers, you may have a battery pack
line go directly to the motor, and when charging the battery, you may be
applying the higher charging voltage to the motor. I took out a accessory
drive motor one time, because there was only one contactor on one battery
line. This motor was arcing to ground cause by the inductive path of the
brush dust while the battery charger was on.

These large contactor's coils may draw up to 5 amps on 12 vdc and has taken
out driver circuits in a controller that may control a main contactor. It
is best to use a Zener Overvoltage Transient Suppressor across all the
contactor coils. I use NTE 4933 for 12 V circuits and NTE 4999 for 180 V.

To reduce my 12 volt load on these contactors, I use line voltage
contactors, meaning the contactor coils use the battery pack voltage to
operate these coils. Line voltage contactors design for a EV are size for
the battery pack, where they will take a overvoltage or more than the
equalize charging voltage of the battery and the contactor will stay open
even if the battery pack drops below the LOW VOLTAGE LIMIT SET BY THE
CONTROLLER. My 12 V ignition turns on 250 VDC relays that is rated for 10
amps and only use 0.1 amp on a 180 volt battery pack voltage to turn on
these contactors.

Roland






----- Original Message -----
From: "David Hrivnak" <[email protected]>
To: <[email protected]>
Sent: Wednesday, October 17, 2007 7:27 PM
Subject: [EVDL] Contractor/Manual disconnect/Naked?


> I am in the process of building my first EV. I will have 72V and will be
> using an Altrax 7245 controller and as such will pull up to 450 amps. As
> I
> am laying out the system it seems prudent to install an emergency cutoff
> or
> a contactor just in case there is a failure and I end up with a runaway
> electric motor.
>
>
>
> Do you think this is prudent to design in or do most EV'ers go "naked" so
> to
> speak with no emergency cut out? If you do have an emergency cut off do
> most use a manual kill switch or contactor? It looks like a contactor
> will
> be a lot easier to design in.
>
>
>
> Thank you
>
>
>
> David J. Hrivnak
>
> <http://www.hrivnak.com> www.hrivnak.com
>
> Personal Account WWJD?
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Discussion Starter #3
All answers are 'yes'.


Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Hrivnak
Sent: Wednesday, October 17, 2007 6:28 PM
To: [email protected]
Subject: [EVDL] Contractor/Manual disconnect/Naked?

I am in the process of building my first EV. I will have 72V and will be using an Altrax 7245 controller and as such will pull up to 450 amps. As I am laying out the system it seems prudent to install an emergency cutoff or a contactor just in case there is a failure and I end up with a runaway electric motor.



Do you think this is prudent to design in or do most EV'ers go "naked" so to speak with no emergency cut out? If you do have an emergency cut off do most use a manual kill switch or contactor? It looks like a contactor will be a lot easier to design in.



Thank you



David J. Hrivnak

<http://www.hrivnak.com> www.hrivnak.com

Personal Account WWJD?



_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Discussion Starter #4
Hehe...I have a related question I suppose. It was always my
understanding that the emergency breaker was considered necessary for
just the reason you cite. And indeed my (recently acquired) truck has a
big 220v breaker in the dash, matching up with the emergency cutoff
shown on the schematics. I can see the wires that seem to go to/from it
through the firewall. But the other day I figured it'd be a good idea to
test...and when I flipped the breaker nothing happened. I could still
drive the truck, the accessories still worked, nothing seems different.

Anybody know why this might be, other than someone simply bypassing it?
Is there a realistic possibility of a runaway condition? Should I be
worried?

Don't mean to hijack your thread, David...but thanks to anybody who has
some advice.

Hunter

David Hrivnak wrote:
> I am in the process of building my first EV. I will have 72V and will be
> using an Altrax 7245 controller and as such will pull up to 450 amps. As I
> am laying out the system it seems prudent to install an emergency cutoff or
> a contactor just in case there is a failure and I end up with a runaway
> electric motor.
>
>
>
> Do you think this is prudent to design in or do most EV'ers go "naked" so to
> speak with no emergency cut out? If you do have an emergency cut off do
> most use a manual kill switch or contactor? It looks like a contactor will
> be a lot easier to design in.
>
>
>
> Thank you
>
>
>
> David J. Hrivnak
>
> <http://www.hrivnak.com> www.hrivnak.com
>
> Personal Account WWJD?
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Discussion Starter #5
You may have contact freeze. If a breaker frame is not large enough to
interrupted or make the circuit under load, it melt the contacts together.
A circuit breaker should have a large enough frame, (more spacing) and arc
suppression with air vents and magnetic trips instead of thermo trips. This
type of circuit breaker should be mounted vertical for cooling. It has
bottom and top vents.

A good industrial breaker, will have a removable cover and you can perform
maintenance on the contacts or even replace the contacts with a contact kit
when needed. Can change the overload ratings of the circuit breaker in a
certain range.

Roland




----- Original Message -----
From: "Hunter Cook" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, October 17, 2007 10:12 PM
Subject: Re: [EVDL] Contractor/Manual disconnect/Naked?


> Hehe...I have a related question I suppose. It was always my
> understanding that the emergency breaker was considered necessary for
> just the reason you cite. And indeed my (recently acquired) truck has a
> big 220v breaker in the dash, matching up with the emergency cutoff
> shown on the schematics. I can see the wires that seem to go to/from it
> through the firewall. But the other day I figured it'd be a good idea to
> test...and when I flipped the breaker nothing happened. I could still
> drive the truck, the accessories still worked, nothing seems different.
>
> Anybody know why this might be, other than someone simply bypassing it?
> Is there a realistic possibility of a runaway condition? Should I be
> worried?
>
> Don't mean to hijack your thread, David...but thanks to anybody who has
> some advice.
>
> Hunter
>
>
David Hrivnak wrote:
> > I am in the process of building my first EV. I will have 72V and will
> > be
> > using an Altrax 7245 controller and as such will pull up to 450 amps.
> > As I
> > am laying out the system it seems prudent to install an emergency cutoff
> > or
> > a contactor just in case there is a failure and I end up with a runaway
> > electric motor.
> >
> >
> >
> > Do you think this is prudent to design in or do most EV'ers go "naked"
> > so to
> > speak with no emergency cut out? If you do have an emergency cut off do
> > most use a manual kill switch or contactor? It looks like a contactor
> > will
> > be a lot easier to design in.
> >
> >
> >
> > Thank you
> >
> >
> >
> > David J. Hrivnak
> >
> > <http://www.hrivnak.com> www.hrivnak.com
> >
> > Personal Account WWJD?
> >
> >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Registered
Joined
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Discussion Starter #6
Maybe it is the breaker for charging?

If this is indeed supposed to be your battery
disconnect, then I would quickly inspect what is
wrong - either its contacts overheated and welded,
or it nuisance-tripped too often and a previous
owner or installer bypassed it....

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Hunter Cook
Sent: Wednesday, October 17, 2007 9:12 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Contractor/Manual disconnect/Naked?

Hehe...I have a related question I suppose. It was always my understanding that the emergency breaker was considered necessary for just the reason you cite. And indeed my (recently acquired) truck has a big 220v breaker in the dash, matching up with the emergency cutoff shown on the schematics. I can see the wires that seem to go to/from it through the firewall. But the other day I figured it'd be a good idea to test...and when I flipped the breaker nothing happened. I could still drive the truck, the accessories still worked, nothing seems different.

Anybody know why this might be, other than someone simply bypassing it?
Is there a realistic possibility of a runaway condition? Should I be worried?

Don't mean to hijack your thread, David...but thanks to anybody who has some advice.

Hunter

David Hrivnak wrote:
> I am in the process of building my first EV. I will have 72V and will
> be using an Altrax 7245 controller and as such will pull up to 450
> amps. As I am laying out the system it seems prudent to install an
> emergency cutoff or a contactor just in case there is a failure and I
> end up with a runaway electric motor.
>
>
>
> Do you think this is prudent to design in or do most EV'ers go "naked"
> so to speak with no emergency cut out? If you do have an emergency
> cut off do most use a manual kill switch or contactor? It looks like
> a contactor will be a lot easier to design in.
>
>
>
> Thank you
>
>
>
> David J. Hrivnak
>
> <http://www.hrivnak.com> www.hrivnak.com
>
> Personal Account WWJD?
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Registered
Joined
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70 Posts
Discussion Starter #7
It is certainly a good idea to have a manual disconnect switch. Not
only as an out in a runaway situation (which is very rare), but also as
a convenient safety disconnect when working on the system.
EV Parts has some here:
http://www.evparts.com/shopping/index.php?id=669

Personally, I have had a full-on runaway experience, but it was not on
an EV. It was my 69 Nova hot rod. It was (and still is) a very serious
muscle car making an easy 300+ horsepower. I was crossing an
intersection on a fairly steep hill with a dip just on the other side.
At the green light I took off and noticed a car that was running the
light so it pressed a bit harder. When I was on the upside of the dip,
the left motor mount broke. This let the engine raise up on that side
which pulled the mechanical throttle wide open. It also pulled the
clutch pivot rod out of socket, so now I have full throttle and no
clutch. Now, in a full scream burnout, I am trying to keep it straight
as the rear end wants to be in front and there is traffic ahead of me.
The tac is pegged and I realize something's gotta give! The brakes are
helping a bit, but not enough. Finally, I gained enough sense to turn
the key off. Life is full of surprises. I certainly could have used a
Big Red Button at that time!

Ken



-----Original Message-----
From: Cor van de Water <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Fri, 19 Oct 2007 1:41 am
Subject: Re: [EVDL] Contractor/Manual disconnect/Naked?



Maybe it is the breaker for charging?

If this is indeed supposed to be your battery
disconnect, then I would quickly inspect what is
wrong - either its contacts overheated and welded,
or it nuisance-tripped too often and a previous
owner or installer bypassed it....

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of
Hunter Cook
Sent: Wednesday, October 17, 2007 9:12 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Contractor/Manual disconnect/Naked?

Hehe...I have a related question I suppose. It was always my
understanding that
the emergency breaker was considered necessary for just the reason you
cite. And
indeed my (recently acquired) truck has a big 220v breaker in the dash,
matching
up with the emergency cutoff shown on the schematics. I can see the
wires that
seem to go to/from it through the firewall. But the other day I figured
it'd be
a good idea to test...and when I flipped the breaker nothing happened.
I could
still drive the truck, the accessories still worked, nothing seems
different.

Anybody know why this might be, other than someone simply bypassing it?
Is there a realistic possibility of a runaway condition? Should I be
worried?

Don't mean to hijack your thread, David...but thanks to anybody who has
some
advice.

Hunter

David Hrivnak wrote:
> I am in the process of building my first EV. I will have 72V and will
> be using an Altrax 7245 controller and as such will pull up to 450
> amps. As I am laying out the system it seems prudent to install an
> emergency cutoff or a contactor just in case there is a failure and I
> end up with a runaway electric motor.
>
>
>
> Do you think this is prudent to design in or do most EV'ers go
"naked"
> so to speak with no emergency cut out? If you do have an emergency
> cut off do most use a manual kill switch or contactor? It looks like
> a contactor will be a lot easier to design in.
>
>
>
> Thank you
>
>
>
> David J. Hrivnak
>
> <http://www.hrivnak.com> www.hrivnak.com
>
> Personal Account WWJD?
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev


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