[EVDL] Which contactor for 70V?

David Nelson <[email protected]> wrote:

> I was testing out a logic board for someone today and unfortunately I
> didn't disconnect the line contactor so the 12V coil got 67V for a bit
> too long. Dissection showed that the coil wires melted the insulation
> and then shorted. The contacts weren't looking too good either,
> probably from not having a precharge setup for most of its life. The
> contactor was a White Rodgers/RBM type 586-105111-3 with a 12V coil.
> The spec sheet lists this as a 200A continuous, 600A inrush contactor
> for 24&36VDC. Max safe coil voltage is 110% of nominal coil voltage
>
> My Gizmo was originally a 48V nominal system. The Sevcon Controller
> has a contactor driver circuit which has three modes. One mode is pack
> voltage to the contactor coil, one is 24V continuous through the
> controllers PWM circuit, and the one I've been running is 24V for 1
> sec and then 16V continuous through the PWM. The PWM is at 650Hz so it
> is audible.
>
> Two things, it looks like this contactor is undersized for a 64V
> nominal LiFePO4 setup with a 500A controller. Second, it looks like
> the coil has been over driven its whole life.
>
> For the time being I installed a White-Rodgers/RBM type 586-120111
> with a 48V coil with a 100ohm power resistor in line with the coil. It
> looks like this will keep the coil voltage within reason for the time
> being. I'm still concerned, however, that this contactor isn't rated
> for 70V.
>
> I've been looking around for a replacement but think the safe thing to
> do would be to get a properly rated contactor. I like the quiet of a
> contactor run from the pack voltage but am willing to live with one
> with a 24V/16V coil and go back to hearing the 650Hz buzz.
>
> I've found looked at a Tyco LEV100A4ANG but it only gives a 100A
> continuous current rating. Periodically have a drive of 30-45 min with
> a battery current of 135A and I don't want to burn out the contactor.
>
> Any suggestions?
>
> --
> David D. Nelson
> http://evalbum.com/1328
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20110306/c7729600/attachment.html
_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

Lee Hart <[email protected]> wrote:

> On 3/7/2011 7:44 PM, David Nelson wrote:
> > I just need to decide if I want to have the constant buzz from the
> controller's PWM
> > circuitry and not have to worry about an economizer circuit or get a
> > 32-95VDC coil and have to come up with an economizer circuit.
>
> The simplest economizer is a resistor and capacitor in parallel, placed
> in series with the coil. Simple, reliable, and silent. Size the resistor
> for the desired holding voltage (typically 1 to 3 times the coil
> resistance, giving 1/2 to 1/4 of the coil's rated voltage to hold it in.
> Size the capacitor for about a 0.05 second time constant with the resistor.
>
> > The 9-36VDC coil has a max inrush current of 3.8A but the contactor
> > circuit in the controller has a limit of 2A. Any way to estimate the
> > inrush current at 24V?
>
> Measure it, or ask the manufacturer.
>
> My guess would be that the actual coils is about 12v. A 12v coil will
> pull in at 75% of rated voltage, or 9v. At 9v, the internal PWM circuit
> would just be fully on.
>
> As the voltage goes higher, the PWM allows an initial "hit" of full
> voltage, then backs the duty cycle off to get 6v or whatever to hold it
> in. As a guess, the initial "hit" is 3.8 amps at 36v, meaning the actual
> coil is R = 36v/3.8a = 9.5 ohms.
>
> The trouble with "clever" electronics is that what the "smart" contactor
> does is not coordinated with what the "smart" controller does. The
> contactor's designer assumes you're switch it with a dumb old switch or
> relay. The controller's designer assumes you're using a dumb old
> contactor. The two electronic circuits can fight and argue over who is
> in control.
>
> So, the controller's electronics may current-limit at 2 amps, which will
> mess up the contactor's circuit. Or that the controller has no
> higher-current surge capability, and will fail if asked to supply more
> than 2 amps.
>
> Your choices to avoid this kind of argument between "smarts",
>
> - Use a dumb contactor with a smart controller.
> - Or a smart controller with a dumb contactor.
> - Or drive a small relay with the smart controller, and
> use the relay's contact to switch the smart contactor.
> - Or take a chance and experiment. The drawback is that
> if it fails, you break an expensive controller or
> contactor!
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20110308/df994601/attachment.html
_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

David Nelson wrote:
> I did find an eBay seller selling the EV200AAANA for $132 for a
> pair. This contactor has an electronic economizer circuit attached.
> My Sevcon controller will PWM the pack voltage at 24V for 1 sec and
> then drop the voltage to 16V. What I'm wondering about is if this
> PWM signal at 650Hz will likely be a problem for this economizer
> circuit.

I would assume that the EV200's internal economizer and the Sevcon's
economizer will interfere with each other. Both are trying to do the
same thing; switch the coil on/off rapidly to keep its average current
lower.

The EV200 coil is rated for 9-36vdc. The coil itself wouldn't care if
the Sevcon pulsed it at 64vdc at a duty cycle that averaged 24v; but the
EV200's economizer is likely to fail due to the high peak voltage.

You could experiment; but it's a pretty expensive part to experiment
with. Failures could also create safety problems; the transistors
driving this coil will fail *on*!

> The other issue is that the data sheet lists 3.8A as the max inrush
> current and the controller is only rated up to 2A.

My guess is that the EV200 has a coil that measures about R = 36v/3.8a =
9.5 ohms. The peak current would only be 3.6 amps if you powered it at
the full 36vdc.

To get the peak current below 2 amps, you would have to keep the peak
voltage below V = IR = 2a x 9.5ohms = 19 volts.

> Maybe I'd be better off putting a power resistor in series with the
> coil and using pack voltage which is <70V (~64V nominal).

I don't think a series resistor is a good approach. The EV200 economizer
is likely to be a transistor and a freewheel diode. The transistor turns
on fully when first powered, then cycles on/off to reduce the average
coil current. With a resistor in series, when the transistor turns off,
it gets hit with your full pack voltage. They probably didn't use a high
enough voltage transistor to withstand this.

You could try a power zener diode in series. A 51v zener would keep the
voltage to the EV200 at 19v peak even if the pack is at 70v. But if the
pack dips below 60v, you'd have less than 9v on the EV200 coil and it
won't pull in. The power dissipation in that zener is also quite high.

> I don't really have room to install another relay to control the
> contactor. Ask Lee. He knows how little room is in a Gizmo.
> Suggestions?

I know, it's crowded. But I don't see any way to use your EV200 as-is
unless you power it from a tap the pack so it won't see over 36vdc.
Unfortunately, that creates problems for the pack.

An extra relay probably *is* the smallest, most efficient way to handle
this situation. This relay can be pretty small; less than 1 cu.inch.

Use the controller to drive the relay coil. The relay can have a 24vdc
coil used with the Sevcon's economizer (you're not likely to hear the
650 Hz in a small enclosed relay). Or, use a 72vdc coil relay and let
the Sevcon power it directly. Use the contacts of this relay to switch
the EV200 coil to the 12vdc system.

> Finally, just to clarify, the + terminal on the contactor needs to be
> toward the positive end of the circuit, right? My circuit is +
> battery - fuse - contactor positive - contactor negative - the rest
> of the stuff - negative battery terminal. I assume that is so that
> the magnetic blow outs work properly.

The + and - on the contacts indicates the preferred direction of
*current* flow (assuming it flows from + to -). If the contactor is
between motor controller and battery, then contactor + goes to battery
+. (Or if the contactor is in the negative side, then contactor - goes
to battery -).

If the contactor is used to connect a charger to the battery, then
contact + goes to charger + (or contact - goes to charger -).
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

Mark Grasser <[email protected]> wrote:
> I have two on my desk at home. Not there now but I have opened it up. The
> board is accessible and I would imagine could be reverse engineered.
>

It looks like it would be easy to wire directly to the coil and bypass
the circuit entirely.

> Sincerely,
> Mark Grasser
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of Lee Hart
> Sent: Tuesday, March 22, 2011 11:47 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Which contactor for 70V?
>
> David Nelson wrote:
>> I did find an eBay seller selling the EV200AAANA for $132 for a
>> pair. This contactor has an electronic economizer circuit attached.
>> My Sevcon controller will PWM the pack voltage at 24V for 1 sec and
>> then drop the voltage to 16V. What I'm wondering about is if this
>> PWM signal at 650Hz will likely be a problem for this economizer
>> circuit.
>
> I would assume that the EV200's internal economizer and the Sevcon's
> economizer will interfere with each other. Both are trying to do the
> same thing; switch the coil on/off rapidly to keep its average current
> lower.

That was what I was wondering when I saw the economizer circuit board.

>
> The EV200 coil is rated for 9-36vdc. The coil itself wouldn't care if
> the Sevcon pulsed it at 64vdc at a duty cycle that averaged 24v; but the
> EV200's economizer is likely to fail due to the high peak voltage.
>

So it sounds very likely that hooking directly to the coil wires with
the Sevcon pulsing 24V for 1 sec and then dropping back to 16V would
be just fine. I would just have very short coil leads. Is there a good
chance that the 650Hz PWM would be audible?

> You could experiment; but it's a pretty expensive part to experiment
> with. Failures could also create safety problems; the transistors
> driving this coil will fail *on*!
>
>> The other issue is that the data sheet lists 3.8A as the max inrush
>> current and the controller is only rated up to 2A.
>
> My guess is that the EV200 has a coil that measures about R = 36v/3.8a =
> 9.5 ohms. The peak current would only be 3.6 amps if you powered it at
> the full 36vdc.
>
> To get the peak current below 2 amps, you would have to keep the peak
> voltage below V = IR = 2a x 9.5ohms = 19 volts.
>
>> Maybe I'd be better off putting a power resistor in series with the
>> coil and using pack voltage which is <70V (~64V nominal).
>
> I don't think a series resistor is a good approach. The EV200 economizer
> is likely to be a transistor and a freewheel diode. The transistor turns
> on fully when first powered, then cycles on/off to reduce the average
> coil current. With a resistor in series, when the transistor turns off,
> it gets hit with your full pack voltage. They probably didn't use a high
> enough voltage transistor to withstand this.

Ok, so with the PWM off cycle the voltage would climb rapidly and
likely burn up the diode before the PWM on cycle pulled it back down.

>
> You could try a power zener diode in series. A 51v zener would keep the
> voltage to the EV200 at 19v peak even if the pack is at 70v. But if the
> pack dips below 60v, you'd have less than 9v on the EV200 coil and it
> won't pull in. The power dissipation in that zener is also quite high.

That wouldn't be good. Under a heavy load with cold batteries the I've
seen the voltage drop to 56V so then the contactor would drop out. Not
good on the life of the contacts or of the driver if it happened at
the wrong time.

>
>> I don't really have room to install another relay to control the
>> contactor. Ask Lee. He knows how little room is in a Gizmo.
>> Suggestions?
>
> I know, it's crowded. But I don't see any way to use your EV200 as-is
> unless you power it from a tap the pack so it won't see over 36vdc.
> Unfortunately, that creates problems for the pack.
>
> An extra relay probably *is* the smallest, most efficient way to handle
> this situation. This relay can be pretty small; less than 1 cu.inch.
>
> Use the controller to drive the relay coil. The relay can have a 24vdc
> coil used with the Sevcon's economizer (you're not likely to hear the
> 650 Hz in a small enclosed relay). Or, use a 72vdc coil relay and let
> the Sevcon power it directly. Use the contacts of this relay to switch
> the EV200 coil to the 12vdc system.

I was hoping to not have to use the 12vdc system to power the
contactor. It is sounding like the only to change this is to either
power the coil directly with the Sevcon PWM circuit which might be
pushing the limits of the Sevcon or get an EV200 with a different coil
rating. I'll start looking for a 24V or 70V relay. Any suggestions off
hand?

Thank you for all your help. I'll rest easier when I have a properly
rated contactor in place.

--
David D. Nelson
http://evalbum.com/1328

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

David Nelson <[email protected]> wrote:
> On Tue, Mar 22, 2011 at 8:02 AM, Mark Grasser <[email protected]> wrote:
>> I have two on my desk at home. Not there now but I have opened it up. The
>> board is accessible and I would imagine could be reverse engineered.
>>
>
> It looks like it would be easy to wire directly to the coil and bypass
> the circuit entirely.
>
>> Sincerely,
>> Mark Grasser
>>
>>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]] On Behalf
>> Of Lee Hart
>> Sent: Tuesday, March 22, 2011 11:47 AM
>> To: Electric Vehicle Discussion List
>> Subject: Re: [EVDL] Which contactor for 70V?
>>
>> David Nelson wrote:
>>> I did find an eBay seller selling the EV200AAANA for $132 for a
>>> pair. This contactor has an electronic economizer circuit attached.
>>> My Sevcon controller will PWM the pack voltage at 24V for 1 sec and
>>> then drop the voltage to 16V. What I'm wondering about is if this
>>> PWM signal at 650Hz will likely be a problem for this economizer
>>> circuit.
>>
>> I would assume that the EV200's internal economizer and the Sevcon's
>> economizer will interfere with each other. Both are trying to do the
>> same thing; switch the coil on/off rapidly to keep its average current
>> lower.
>
> That was what I was wondering when I saw the economizer circuit board.
>
>>
>> The EV200 coil is rated for 9-36vdc. The coil itself wouldn't care if
>> the Sevcon pulsed it at 64vdc at a duty cycle that averaged 24v; but the
>> EV200's economizer is likely to fail due to the high peak voltage.
>>
>
> So it sounds very likely that hooking directly to the coil wires with
> the Sevcon pulsing 24V for 1 sec and then dropping back to 16V would
> be just fine. I would just have very short coil leads. Is there a good
> chance that the 650Hz PWM would be audible?
>
>> You could experiment; but it's a pretty expensive part to experiment
>> with. Failures could also create safety problems; the transistors
>> driving this coil will fail *on*!
>>
>>> The other issue is that the data sheet lists 3.8A as the max inrush
>>> current and the controller is only rated up to 2A.
>>
>> My guess is that the EV200 has a coil that measures about R = 36v/3.8a =
>> 9.5 ohms. The peak current would only be 3.6 amps if you powered it at
>> the full 36vdc.
>>
>> To get the peak current below 2 amps, you would have to keep the peak
>> voltage below V = IR = 2a x 9.5ohms = 19 volts.
>>
>>> Maybe I'd be better off putting a power resistor in series with the
>>> coil and using pack voltage which is <70V (~64V nominal).
>>
>> I don't think a series resistor is a good approach. The EV200 economizer
>> is likely to be a transistor and a freewheel diode. The transistor turns
>> on fully when first powered, then cycles on/off to reduce the average
>> coil current. With a resistor in series, when the transistor turns off,
>> it gets hit with your full pack voltage. They probably didn't use a high
>> enough voltage transistor to withstand this.
>
> Ok, so with the PWM off cycle the voltage would climb rapidly and
> likely burn up the diode before the PWM on cycle pulled it back down.
>
>>
>> You could try a power zener diode in series. A 51v zener would keep the
>> voltage to the EV200 at 19v peak even if the pack is at 70v. But if the
>> pack dips below 60v, you'd have less than 9v on the EV200 coil and it
>> won't pull in. The power dissipation in that zener is also quite high.
>
> That wouldn't be good. Under a heavy load with cold batteries the I've
> seen the voltage drop to 56V so then the contactor would drop out. Not
> good on the life of the contacts or of the driver if it happened at
> the wrong time.
>
>>
>>> I don't really have room to install another relay to control the
>>> contactor. Ask Lee. He knows how little room is in a Gizmo.
>>> Suggestions?
>>
>> I know, it's crowded. But I don't see any way to use your EV200 as-is
>> unless you power it from a tap the pack so it won't see over 36vdc.
>> Unfortunately, that creates problems for the pack.
>>
>> An extra relay probably *is* the smallest, most efficient way to handle
>> this situation. This relay can be pretty small; less than 1 cu.inch.
>>
>> Use the controller to drive the relay coil. The relay can have a 24vdc
>> coil used with the Sevcon's economizer (you're not likely to hear the
>> 650 Hz in a small enclosed relay). Or, use a 72vdc coil relay and let
>> the Sevcon power it directly. Use the contacts of this relay to switch
>> the EV200 coil to the 12vdc system.
>
> I was hoping to not have to use the 12vdc system to power the
> contactor. It is sounding like the only to change this is to either
> power the coil directly with the Sevcon PWM circuit which might be
> pushing the limits of the Sevcon or get an EV200 with a different coil
> rating. I'll start looking for a 24V or 70V relay. Any suggestions off
> hand?
>
> Thank you for all your help. I'll rest easier when I have a properly
> rated contactor in place.
>
> --
> David D. Nelson
> http://evalbum.com/1328
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>



--
http://www.evalbum.com/2149

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

dave cover <[email protected]> wrote:
> You can find 48v Curits-Albright contactors on eBay all the time. IIRC
> they occasionally show up with higher voltage coils from time to time.
>
> DAC
>


--
David D. Nelson
http://evalbum.com/1328

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...

Dave Nelson wrote:
> It looks like it would be easy to wire directly to the coil and bypass
> the circuit entirely.

That would keep the two economizer circuits from fighting. But it
doesn't solve the problem that the 9.5 ohm coil in the EV200 will draw
way over the 2 amp peak current limit of the Sevcon's coil driver.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

Click to expand...