# EV200 contactor economizer circuit with broken component



## mora (Nov 11, 2009)

Hello,

few days ago I happened to fry one of my EV200 contactors. I was remounting contactors and contactor coil positive wire happened to touch shunt terminal. Shunt was connected to controller and there was some voltage present at the capacitors. Both battery pack leads were disconnected from the pack. There was a small spark and contactor made clicking sound as it would have been activated normally. I quickly noticed the contactor would remain open even if I fed it with +12V. Miraculously nothing else went bad.

Contactor coil is rated for max 36V DC I believe. Today I thought I'd see what happened and where so I took the small cover off from the side and noticed one broken component very near the wires.

I think I could replace that component if I happen to know what it is. I haven't played around with this small stuff much but I could take a guess about it being a diode. There is no writing on top of this component.

Does this contactor work without this circuit? In case component replacement doesn't help I might use it without this economizer board.

The cracked component is the only component above the black wire in right side. You can see a crack on it from the second picture.


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## major (Apr 4, 2008)

mora said:


> Does this contactor work without this circuit? In case component replacement doesn't help I might use it without this economizer board.


Hi mora,

Yes, it does work without the economizer. But the coil is about 3 ohms. So it will draw a lot of current from a 12 or 24V circuit. Perhaps enough to burn up the contactor coil. I think the hold current with the economizer is less than 1 amp. So if you can pull-in the contactor at 4A or higher and then reduce it to 1A, it will work. It might work at 4A just fine, but 48W is a lot just to keep the circuit closed.

Regards,

major


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## gaminde (Sep 18, 2011)

mora said:


> Hello,
> 
> few days ago I happened to fry one of my EV200 contactors. I was remounting contactors and contactor coil positive wire happened to touch shunt terminal. Shunt was connected to controller and there was some voltage present at the capacitors. Both battery pack leads were disconnected from the pack. There was a small spark and contactor made clicking sound as it would have been activated normally. I quickly noticed the contactor would remain open even if I fed it with +12V. Miraculously nothing else went bad.
> 
> ...


Well here is a guess

if its wired across the red and black leads and these leads go to a contactor then yes it could be a kick back diode for the coil off kickback

if its wired just one lead or the other in series then maybe a fuse

any other config could be any two lead device resistor, capicator, how is it wired ???


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## gaminde (Sep 18, 2011)

mora said:


> Hello,
> 
> few days ago I happened to fry one of my EV200 contactors. I was remounting contactors and contactor coil positive wire happened to touch shunt terminal. Shunt was connected to controller and there was some voltage present at the capacitors. Both battery pack leads were disconnected from the pack. There was a small spark and contactor made clicking sound as it would have been activated normally. I quickly noticed the contactor would remain open even if I fed it with +12V. Miraculously nothing else went bad.
> 
> ...


Well here is a guess

if its wired across the red and black leads and these leads go to a contractor then yes it could be a kick back diode for the coil off kickback

if its wired just one lead or the other in series then maybe a fuse

any other config could be any two lead device resistor, capacitor, how is it wired ???

*Also trying to look at the traces the red wire goes to a component that looks the same put an ohm meter on it there maybe fuses 
*


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## poprock (Apr 29, 2010)

major said:


> Hi mora,
> 
> Yes, it does work without the economizer. But the coil is about 3 ohms. So it will draw a lot of current from a 12 or 24V circuit. Perhaps enough to burn up the contactor coil. I think the hold current with the economizer is less than 1 amp. So if you can pull-in the contactor at 4A or higher and then reduce it to 1A, it will work. It might work at 4A just fine, but 48W is a lot just to keep the circuit closed.
> 
> ...


Same fate for two of mine. Being unknowledgeable (read dumb ) I removed the economiser and have used them on my 12v go-kart, so far without flames. #1 black power in; #2 black power out to on/off throttle switch.
They hold ok at 12v.


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## qdlaty (Jul 26, 2010)

This "economizer" is sort of a chopper/quick switch that shutters the current keeping the contactor closed on and off quick enough to not open it. This is why you see decreased current consumption after initial close.
Simply reducing the supply current won't work - Czonka will open.
As around is someone has welded EV200 and he is willing to share the economizer with you or try to find out which part was fried on your PCB.


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## Coulomb (Apr 22, 2009)

mora said:


> I think I could replace that component if I happen to know what it is.


I don't think it's a fuse; I don't believe a fuse would fail in that particular way. My guess is a resistor, diode, or surge suppressor.

It would help us guess if you can tell whether the component is across the 12 V input, or in series with it (by inspection and/or buzzing with a multimeter, possibly after removing the part, which may well be shorted).

Even better would be a 3-alphanumeric code (sometimes 4) that might be found on a good unit, possibly on the underside. These codes often replace a full part number on surface mount components. (Though this one seems to have plenty of room for a full part number).

The final option is to remove a good part from a good economizer, and test it to see what its resistance is at various voltages. My guess would be a transient absorber, which means you'd have to apply at least 40 V, possibly more, with a resistor in series (say 1K to 10K, value is not critical) before you see it conduct. You'd have a multimeter across the device under test. It may also be a zener diode, so 0.7 V drop in one direction and around 40 V in the other.

A simple test might be to remove the bad component first, and see if the contactor pulls in with 12 V. If so, it's a protective device, and can be replaced with a suitable protective device, say a 2 W 18 V zener diode (cathode to +12 V input, of course).


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## mora (Nov 11, 2009)

I removed the broken component. Black wire is connected to that component. Nothing else connects to that end of component. Black wire doesn't connect to any other component or via either. So if that component is missing circuit isn't complete. There was no writing on the other side but PCB had silkscreen printing "L2". Should I try bridging that component with some wire?


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## gaminde (Sep 18, 2011)

mora said:


> I removed the broken component. Black wire is connected to that component. Nothing else connects to that end of component. Black wire doesn't connect to any other component or via either. So if that component is missing circuit isn't complete. There was no writing on the other side but PCB had silkscreen printing "L2". Should I try bridging that component with some wire?


Here is what I suggested:

The black wire circuit has a blown part that is in series, now right next to the black wire is the red wire with what looks like the same component in series, put you ohm meter on that component both forward and reverse bias (switch leads) and read with all ohm settings. it most likely is not a serge suppressor as these connect to ground to short out the serge. measure that component and this may tell you what it could be. Ill bet on fuse or diode.


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## gaminde (Sep 18, 2011)

mora said:


> I removed the broken component. Black wire is connected to that component. Nothing else connects to that end of component. Black wire doesn't connect to any other component or via either. So if that component is missing circuit isn't complete. There was no writing on the other side but PCB had silkscreen printing "L2". Should I try bridging that component with some wire?


L2 could be a coil, where is the L2 marking, it could also be the leads going to the coil your trying to feed.


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## gaminde (Sep 18, 2011)

I just looked up smd coding and found a paper that talks about zener's and how there color coded with bands on the ends ??? its too large to upload on this site so a google search is in order.


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## Coulomb (Apr 22, 2009)

mora said:


> .. So if that component is missing circuit isn't complete.


Good. So we know it is in series with the negative input lead.



> There was no writing on the other side but PCB had silkscreen printing "L2".


Ah. I'd say it's 99% sure that this component is an inductor. 



> Should I try bridging that component with some wire?


You could do that, but I'd run it from a current limited source like a power supply that you can set the current limit on. I'd start with perhaps a 1 amp limit, even though it might not pull in at that current. There is a good chance that whatever caused L2 to overheat will still be causing way too much current to flow. If the power supply limits itself to a low voltage with 1A flowing continuously, you can say with reasonable certainty that there is still a fault there.

[ Edit: one amp at 12 V is still plenty of power to let smoke out of components. So be very watchful still; don't imagine that the 1 A limit will prevent all possible adverse events, like components burning up. ]

If it all works, [ edit 2: and you don't get a better clue about the value of L2, e.g. by measuring the inductance from a good economizer ] you could do worse than replacing L2 with a surface mount inductor that is capable of handling 3.8 A peak. It looks like a 1515 (4mm x 4mm) component to me, but it's hard to tell from the photo. Any inductance in the range 5 to 50 microhenries would be appropriate, I'd guess. Perhaps less, perhaps down to one microhenry, because of the rather large currents involved.

It will probably work fine with L2 shorted permanently; it's just that a little more of a spike may find its way back into the 12 V circuits that way. But consider that L2 acted as a kind of fuse last time; replacing it with another inductor may prevent worse burning up of components if this sort of thing happens again. It doesn't have to be an accident with a cable; voltage spikes in cars are a fact of life. The inductor will also help protect the economizer circuit from moderate spikes on the 12 V line from elsewhere. (The accidental cable connecting would be considered a jumbo spike  .)


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## mora (Nov 11, 2009)

That was some great info again. I measured resistance from red wire to that other similar looking component. Multimeter reads something like one ohm to both ends of component. Also components resistance seems to be very low. It is hard to tell where tracings go but I'd say that similar component is in series with red wire.

I'll try replacing the broken component with similar sized (physically) inductor.


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## gaminde (Sep 18, 2011)

So did you try anything yet


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## mora (Nov 11, 2009)

Nothing yet. I'll try to source that component locally first. I don't want to order full reel of inductors just to try if one of them works for me.


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## Coulomb (Apr 22, 2009)

mora said:


> I don't want to order full reel of inductors ...


You should be able to buy a single inductor from the likes of Mouser or Digikey, etc. Freight will cost 10x or 100x the cost of one SMD part, so perhaps buy 10 (for a dollar or two) and have a lifetime supply of spares. There may be a minimum order quantity of 5 or 10 anyway. If the MOQ is something like 1000 or 2000, then just find a similar part number that has a lower MOQ; there will almost certainly be one.

They'll come on a short piece of tape, designed for a pick and place machine, but you can easily peel off the plastic by hand and get them out one component at a time.

[ Edit: re "sourcing locally": there are so many variations of SMD parts (at least 5 main sizes, different maximum currents for inductors, and so on) that usually you can only buy them on-line from companies with large warehouses. There are a few exceptions in my country (Australia), and there may be more in the USA, but I still find it unlikely that you will find an SMD inductor of roughly the right specifications (remember, this one has to withstand the surge current of over 4 A, possibly without saturating) at somewhere "local". Then again, a place like Fry's is pretty big; I haven't been to one recently enough to know what the chances are. ]


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## mora (Nov 11, 2009)

Yea, I took a look at Digikeys online product index. Now I'll just have to find right one. Or some more with different values and have spares too. Those weren't that pricey anyway.

Local store most likely wouldn't have had anything like this in stock but they will order me anything.


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## gaminde (Sep 18, 2011)

mora said:


> Yea, I took a look at Digikeys online product index. Now I'll just have to find right one. Or some more with different values and have spares too. Those weren't that pricey anyway.
> 
> Local store most likely wouldn't have had anything like this in stock but they will order me anything.


Well for a test I would get a finish nail and wind my own coil arround it for a nice round coil and then solder it in. Don't spend any money just yet

Oh yea remove the nail when soldering it in its just a form.


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## gaminde (Sep 18, 2011)

size ohm per 100' ohm per 10'

Solid Wire for
Wire Wrap 30 10.32000 1.03200


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## gaminde (Sep 18, 2011)

Mora sorry I just cracked myself up at your expense,, I see your from Finland and I said use a (finish nail) this is a real small nail in USA for doing wood trim work.

Coulomb you can use a gator tooth


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## mora (Nov 11, 2009)

Hehehe, that was funny. Finnish nails might be good for finishing coil turning.

But should there be some ferrite or other material inside the coil? Or would open coil do? 30 awg, right?


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## gaminde (Sep 18, 2011)

mora said:


> Hehehe, that was funny. Finnish nails might be good for finishing coil turning.
> 
> But should there be some ferrite or other material inside the coil? Or would open coil do? 30 awg, right?


For a test should work what resistance were you reading on the one connected to the red wire .5 ohm or 1 ohm, 1 ohm = 10 feet. 

wonder how they can get that much wire in a SMD part. guess you can wind more than one layer. so you need a real small Finnish girlie nail. or you could wrap it arround another piece of #30. What is the current when in low power mode. I just went out and tried to wind some #26 wire on a small screw GEEZ looked like three pieces of wire your going to need a magnifying glass for sure, size of wire will amount to ohm's and current needed maybe not inrush.


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## mora (Nov 11, 2009)

I measured the other component. It is 4,4mm x 3,1mm. Didn't measure thickness. Uni-T multimeter showed 0.1ohm resistance. Mouser seems to have a good selection of inductors. Digikey didn't seem to have ones with high enough amperage rating. 

I've wound some brushless rc motors before and have some #26 wire left. I could make a crude inductor out of it for testing purposes.


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## Taylorcarter (Oct 8, 2011)

It will work...I guess


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## mora (Nov 11, 2009)

2.5 feet of #26 wire wound around a 3mm metal rod. Soldered in place and applied 12V for less than a second. Flames came through a small chip which was at the other end of the board. I suppose I let the magic smoke out of that chip. Hehe.


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