# [EVDL] Reversing Contactor



## EVDL List (Jul 27, 2007)

Any issues if some these burnt out at the same time?



> Mike Willmon <[email protected]> wrote:
> 
> > Or you could use 4 of the smaller LEV-200's for a smaller application.
> > I would be sure to use ones with aux contacts so you use the Forward Aux
> ...


----------



## EVDL List (Jul 27, 2007)

Right. (of course, that would require two more contactors one for both the
plus and minus!)



> Jeff Major <[email protected]> wrote:
> 
> >
> > --- On Tue, 1/5/10, m gol <[email protected]> wrote:
> ...


----------



## EVDL List (Jul 27, 2007)

Not really, you can effectively isolate the pack from the controller by 
breaking only one of the battery feeds.
What I do for the Mitsubishi is break one with the contactor and one 
with the breaker. So in the Off/Parked state, both leads are actually 
isolated.

Mike




> m gol wrote:
> 
> > Right. (of course, that would require two more contactors one for both
> > the
> ...


----------



## EVDL List (Jul 27, 2007)

For a single motor application the worst you could do if two get welded 
closed while the other two came on is run current through only one set 
of coils. It could potentially make smoke is you stay on it to long 
before you investigate. If a contactor just fails to actuate then 
nothing would happen, and the motor wouldn't move.

In my case for dual motors I add two more of these to get parallel. 
However the extreme case where you have a reverse contactor closed at 
the same time as a parallel contactor, boom direct short across the 
controller output. I have the Reverse/Parallel state interlocked 3 
different ways. It ain't gonna happen.

I still suggest you employ interlocks by using the aux switches on the 
contactors, its the easiest physical assurance that the opposite 
contactor will not close when its counterpart is also closed.

HTH
Mike




> m gol wrote:
> 
> > Any issues if some these burnt out at the same time?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Can you use a reversing contactor if your controller doesn't have an A2 with
a DC series motor? Like a logi?



> Jeff Major <[email protected]> wrote:
> 
> >
> > --- On Tue, 1/5/10, m gol <[email protected]> wrote:
> ...


----------



## EVDL List (Jul 27, 2007)

> m gol wrote:
> > Can you use a reversing contactor if your controller doesn't have an A2 with
> > a DC series motor? Like a logi?
> 
> ...


----------



## EVDL List (Jul 27, 2007)

I'm working on an electric ATV (four-wheeler).
We are doing this as part as my 2-week electric car conversion course in
Fairbanks, AK.
We have the Warp7 all mounted up, and one week to go.

Could someone explain what plug breaking is? In that how does it feel to the
operator?
I would like to duplicate how the original ATV is used. In that there is
usually a momentary switch that is depressed in order to put the quad into
reverse.
It would seem dangerous if it went it to reverse unknowingly.

I have two possible controllers for this project. A 400 amp curtis that has
A2 and a 1100 amp logi that does not have the A2. Both 48-72 volt models.

We plan on using 16 of the 40ah TS from evcomponents.com. I was lucky they
had some in stock...

thanks in advance...
Michael Golub
Fairbanks, AK




> Lee Hart <[email protected]> wrote:
> 
> > m gol wrote:
> > > Can you use a reversing contactor if your controller doesn't have an A2
> ...


----------



## EVDL List (Jul 27, 2007)

Plug breaking is where you switch out the energy driving the motor and
instead let the motor deliver power (as a generator) to an electrical load.
The feeling you get is that of braking. The greater the delivered current
from the motor/generator, the greater the braking effect. As the car slows,
the braking effect quickly becomes less and less effective.
This was a very common method of braking with electric cars build in the
1910-1924 timeframe.
-Myles

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of m gol
Sent: Saturday, January 09, 2010 6:07 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Reversing Contactor

I'm working on an electric ATV (four-wheeler).
We are doing this as part as my 2-week electric car conversion course in
Fairbanks, AK.
We have the Warp7 all mounted up, and one week to go.

Could someone explain what plug breaking is? In that how does it feel to the
operator?
I would like to duplicate how the original ATV is used. In that there is
usually a momentary switch that is depressed in order to put the quad into
reverse.
It would seem dangerous if it went it to reverse unknowingly.

I have two possible controllers for this project. A 400 amp curtis that has
A2 and a 1100 amp logi that does not have the A2. Both 48-72 volt models.

We plan on using 16 of the 40ah TS from evcomponents.com. I was lucky they
had some in stock...

thanks in advance...
Michael Golub
Fairbanks, AK




> Lee Hart <[email protected]> wrote:
> 
> > m gol wrote:
> > > Can you use a reversing contactor if your controller doesn't have an A2
> ...


----------



## EVDL List (Jul 27, 2007)

> m gol wrote:
> > Could someone explain what plug braking is? In that how does it feel
> > to the operator?
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Thank you.
I still haven't found a reversing diagram using a reversing contactor with
no "A2" on the controller.





> Jeff Major <[email protected]> wrote:
> 
> > --- On Sat, 1/9/10, m gol <[email protected]> wrote:
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Reversing a series motor is fairly easy, a dpdt relay reverses the
connections to the field winding connectors ONLY . Or to the Armature
connections ONLY. Not both! that makes the motor reverse when the relay
is energized by your control circuitry. The reversing relay contacts usually
are not strong enough to operate with power applied to the motor so the
sequence is cut off power, activate rev.relay, apply power, cut off power
again when de-energizing rev.relay.
the "A-2" isn't part of the reversing circuit.
Regards,
Dennis Miles



> m gol <[email protected]> wrote:
> 
> > Thank you.
> > I still haven't found a reversing diagram using a reversing contactor with
> ...


----------



## EVDL List (Jul 27, 2007)

...or motor RPM ;-)




> Jeff Major wrote:
> 
> ... The Hairball (Zilla) controls the reversing contactors and I
> suspect will not allow them to activate if there is motor current.
> ...


----------



## EVDL List (Jul 27, 2007)

Why? If you are rolling you can't engage a different gear?
That would be a safety problem or at least a very inconvenient
feature that you *have* to make a full stop before gear change
backwards or forwards.
I like the way the Prius solved this - the motors simply cause
a torque in the selected direction after changing the stick
position, no matter which direction the car is moving in.
So if you are rolling forward, you can brake electrically and
immediately backup just with pedal control.
If you are already rolling backwards, you can increase the
speed with the accelerator.
Moving the stack back to D (Drive) will allow you instantly
to start accelerating forward, if you were still moving 
backwards that means you first go slower backwards.
It is the same as done using clutch and accelerator in a
stick-shift car.

What would be the problem with switching while there is
still motor RPMs? Back-EMF from the motor?
Should the RPMs be below a certain level (say, no more
than 500 or 1000 RPM before allowing the switch?

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Wednesday, January 13, 2010 1:58 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Reversing Contactor

...or motor RPM ;-)




> Jeff Major wrote:
> 
> ... The Hairball (Zilla) controls the reversing contactors and I
> suspect will not allow them to activate if there is motor current.
> ...


----------



## EVDL List (Jul 27, 2007)

> Jeff Major wrote:
> > ...The Hairball (Zilla) controls the reversing contactors and I
> > suspect will not allow them to activate if there is motor current.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

The Hairball will not switch to reverse when it senses any motor RPM, 
motor current or any amount of throttle input.
You have to be stopped with your foot off the accelerator before the 
reverse input will operate.
I have tested this feature while rolling forward, flipped the reverse 
switch, nothing happens but as soon as you reach a complete stop...click 
click, forward contactor drops and reverse contactors come on. THEN you 
may hit the accelerator.

Now if you are not using a Zilla, then you have to design all this 
"Reverse Safety Interlock" yourself. I suspect that most home builders 
will not design all these safety checks in (if any). But this IS the 
reason that paying the little extra for the Zilla is worth it. And the 
wiring is actually way simpler (not more complex like some have 
mentioned) than having to implement your own safety interlock designs. 
The Hairball was designed to make it simpler. And installs typically 
look cleaner than most where all the external safetys have been 
implemented.

Mike




> Lee Hart wrote:
> 
> > Jeff Major wrote:
> >> ...The Hairball (Zilla) controls the reversing contactors and I
> ...


----------

