# how to add coil economiser



## itchyback (May 28, 2014)

Hi,
I have a GV200 from a Model S p85. I somehow need to add a 'coil economiser'. Im fitting the battery and motor from P85 using the VCU by Advantics, Elias says i need it so i'll get it. 
I've been reading up on this and understand its purpose. I've also read conflicting information about using one diode, two, a mixture of a special diode and regular diode or even a capacitor and a resister. Kilovac seems to come with a small circuit board rather than single component. Im honestly way out of my depth to be able to decipher under what conditions and for what reasons i should use any particular solution and even, what type/size diode/capacitor/whatever. 

The best solution i have at this time is buying another contactor with the economiser in it, like the Gigavac GV200-PA EV Contactor from EV west. Hower i think there is a cheaper and faster solution somewhere. 

I'd be very grateful if someone could provide a solution or point me in the right direction of some information that may help me devise my own solution?


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## MattsAwesomeStuff (Aug 10, 2017)

Bottom line...

From what I can tell it doesn't matter and you don't need one, so it's not worth worrying about too much.

An economizer's job, far as I can tell, is to reduce the load on the coil that actuates the contactor. As in, it's hard to pull the switch shut, but after you do, it doesn't take as much power to hold it shut, so you might as well back off a bit.

The entire benefit would be to slightly reduce the energy wasted holding the contactor closed, and maybe reduce heat. If you skip it, you'll lose, I dunno, a few watts? At worst it'll be like a very small lightbulb left on?

On the bad side, anything you do to taper off the power, means you might slow down how fast the contactor moves, which means more arcing and worse contact life. So it seems to me that you're better off using no economizer than one poorly designed.

If the contact was designed to need an economizer (i.e. I cannot withstand a current that doesn't back off once it's closed), that would be odd, but, maybe there are some out there.

http://www.diyelectriccar.com/forums/showthread.php/evdl-coil-economizer-13711.html <-- Does this help?



...

Is that what you're talking about, or are you talking about flyback diodes to prevent the contactor terminals from arcing when they're disconnected and the motor's still spinning?


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## kennybobby (Aug 10, 2012)

It depends whether your contactor has one coil or two coils already built in.
Some GIGA units have 2 coils, pull-in and hold, and they use a timer to turn off the current to the Pull-in, which just leaves the hold coil doing its thing.

The economizer circuit can also be done using PWM for a single coil version, and this can be either current or voltage regulated. It does create electrical noise that might interfere with other circuitry.

In any case you will want to know or measure the R and L of the coil(s) that you will be driving so you can try to match the output parameters of the drive amplifier to the load parameters (e.g. impedance).

there are good discussions here on this site, searching coil economizer circuit.


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## itchyback (May 28, 2014)

Thanks MattsAwesomeStuff. I'm guessing the controller managing the contactors cant handle the few amps needed to keep them open/shut. 
I read that thread 'coil economiser' but got lost in the arguments about the use of a simple resistor across the terminals or resister and capacitor (in my original post). It seems using a zener/mosfet is a better choice than a simple diode, so you dont slow down the separation of the contactor. How that is wired in and sized, i dont know. 

Thanks KennyBobby. I read some of the 'contactor control circuit' thread, that was my reference to 'special diodes' aka Zener diodes. Most of it is above my comprehension. While i have a basic understanding of how a diode, resister, MOSFET etc work alone. I'm having difficulty understanding how they function together in the circuit and why one should be used instead of another and how to size them for my purpose. I'm happy with the learning curve but I'm feeling pretty disheartened trying to comprehend it all. 

The GV200 i have is single coil. Unfortunately though I dont have a multimetre that can measure inductance :/.
I cant seem to find a way to measure this otherwise, seems i might be resigned to buying some contactors, bummer


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## steveob (Nov 10, 2017)

while it isn't a lot of power in the big picture, there is a passive version, just get the right resistor and capacitor and put them in series with the coil.










discussion here:
http://www.diyelectriccar.com/forums/showthread.php/evdl-coil-economizer-13711.html


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## Jimbo69ny (Feb 13, 2018)

Ive been dealing with contactors a lot lately.


Matt isnt correct about not needing them though. You either need one attached to the contactor, or you need a PWM circuit. I know this as a fact because I just tested it. I gave a Kilovac Czonka 3 EV200 A1ANA contactor 12 volts for an hour and it burnt up. Did the same for a contactor with an economizer and it was fine, not even hot. The EV200 was HOT!


I dont use any diodes in my contactor applications but your needs might be different. I dont know what you are doing. Maybe someone else can give you advice on that one.


Dont buy the contactors from EVWest. Too much money. I looked around A LOT and the best deal I found was from this seller on ebay. https://www.ebay.com/itm/Tyco-TE-Re...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649


He sells used contactors with economizers and I have had good luck with them, they just take 20+ days to arrive.


I needed 2 more quickly so I purchased some from this guy. https://www.ebay.com/itm/TE-Connect...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
He just reduced his price and its a great deal. They arrived within 3 days and worked perfectly. They are brand new.


Hope this helps


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## Jimbo69ny (Feb 13, 2018)

PS I looked all over for an economizer circuit to add to a non economized contactor and I couldnt find any affordable options. It was a while ago but I think I found one on mouser but it was something like $70. 



Buy contactors from one of the two links I posted above and move on.


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## steveob (Nov 10, 2017)

Jimbo69ny said:


> PS I looked all over for an economizer circuit to add to a non economized contactor and I couldnt find any affordable options.


Please refer to post 5, unless a resistor and a capacitor are cost prohibitive in your country.


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## Jimbo69ny (Feb 13, 2018)

steveob said:


> Please refer to post 5, unless a resistor and a capacitor are cost prohibitive in your country.


 lol now you want to come over to another thread and start more shit.


I was talking about the economoizer circuit board that is attached to contactors. Not some home built thing. I was looking for something a little more professional for my project. But if it works for you thats great.


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## steveob (Nov 10, 2017)

you just implied there was no cost effective solution while ignoring the post above you (which many people have laying in their parts bin), telling folks to go buy something, then accuse me of starting shit.

feeling persecuted again?


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## Jimbo69ny (Feb 13, 2018)

steveob said:


> you just implied there was no cost effective solution while ignoring the post above you (which many people have laying in their parts bin), telling folks to go buy something, then accuse me of starting shit.
> 
> feeling persecuted again?



LOL you a such a troll. I simply said that *I *couldn't find one. I in no way implied anything by that. In actuality, I gave two very cost effective options. If someone cant afford a $30 contactor they probably shouldn't be working on any battery related projects. A contactor is a pretty major component for safety and functionality. If you want to cheap out on it thats on you.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimmy said:


> If someone cant afford a $30 contactor they probably shouldn't be working on any battery related projects. A contactor is a pretty major component for safety and functionality. If you want to cheap out on it thats on you.


Oh, so, people with limited resources or who don't want to spend as much aren't allowed to have the same hobbies as you. Gotcha.

Also, you're not really one to lecture people on cutting corners for safety considering how you shunned everyone's safety advice on your own build.

Jeez, just running from thread to thread stirring up trouble.


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## steveob (Nov 10, 2017)

Jimbo69ny said:


> I simply said that *I *couldn't find one.


IMMEDIATELY after a post, made hours before yours, describing exactly a cheap economizer, in a thread about adding economisers... And when it is pointed out to you, you get weird. It was right before the post you made about not being able to find one, and I'm the troll.

I'm gonna do duncan a favor and just block you and your nonsense, have fun.


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## itchyback (May 28, 2014)

That got feisty. Written communication is great that it lasts forever, but lacks the nuances of tone and expression that may help clear up any miscommunications. I appreciate both ideas and input. 

I had seen the idea for a capacitor and resistor wired together. 
The maths for how to work out what sizes to use was not clear to me, or if it was explained, i lack the knowledge at this moment to understand it. Looking around on other websites, i did not see the idea widely. My parts bin is also pretty skinny, i bet the bits are only a few dollars and i was pretty keen to try it. However, my goal is for the car to be very highly polished construction, I had made a offroad dirt buggy before this. its was pretty rough but it suited the purpose, although my friends teased me a bit for that. I want this to look almost OEM. I spent $240AUD fixing a mistake of 5mm for my battery box for example, i want this perfect. 

The contactors look much more affordable than EV west so i'll probably go with those. 

This has been a valuable experience learning about Coil economisers and electronics in general, the entire purpose of my build to learn more about electronics. Thank you!


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