The resistor and capacitor are in parallel, then those two are connected to the contactor coil. There is no difference if they are connected at the positive or negative side of the contactor coil. The only thing to check is that the capacitor is oriented the right way, its positive side to the positive supply that supplies the coil. Just put it in series with the coil and measure the voltage drop, then verify that the capacitor + is higher than its negative side.
Do not put a capacitor across the coil, that will only reduce the speed of the contactor and cause severe arcing. You can measure the contactor coil resistance when it is not active - if it has a connector then you can pull the connector off and then measure the coil itself. I expect that as soon as the coil resistance is known, Lee or someone else can make this circuit for you (power resistor + large capacitor) and send it to you for a small fee. Regards, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mike Malmberg Sent: Wednesday, June 26, 2013 11:27 PM To: evdl Subject: Re: [EVDL] negative contactor heating up and BMS analogue control Date: Tue, 25 Jun 2013 22:13:00 -0500 From: Lee Hart <[email protected]> To: Electric Vehicle Discussion List <[email protected]> Subject: Re: [EVDL] EV Digest, Vol 8, Issue 39 Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Mike Malmberg wrote: my responses below and thank you so much > coil has 14 volts The Tyco LEV200 data sheet says it has a 12vdc coil, and is rated for 9.6v minimum, 13.2v maximum. 14v is more than its rated voltage, so it would get hot. My suggestion would be to add a series resistor, with a capacitor in parallel (called a "slugger" circuit). Choose the resistor to drop the steady-state voltage a few volts. Oddly, the data sheet doesn't give the coil resistance, so you'll have to measure it or experiment to find the right resistor value. --So a series resistor on positve or negative side of coil. coil resistance measured with an ohm meter across the coil while the coil is off or energized? Is there some math I need to do to calculate the resistor value that I need? Then, the capacitor in parallel initially applies the full voltage, to make the contactor pull in quickly. Something like a 10,000uF electrolytic capacitor rated at 6vdc or more will do it. --And this capacitor goes across the coil of the contactor, yes? > I realize that the BMS should have control over that contactor, and so my > charger negative should go on the other side of the contactor (controller > side rather than battery side). Will that affect the contactor heating? No. You aren't running enough current for its contact to produce any significant amount of heat. > Also, nobody responded on the bms control question, I flipped the diode > the other way around and I have no throttle at all. I can't help you there. Sounds like you had the diode the right way to begin with. Was it in fact limiting the throttle when the BMS sensed a low cell voltage? --no that was why I started asking questions, it had no effect on the current output at all. when checking it the original way I had it hooked up, I believe I had 5 volts on bms side of the diode and 1.2 volts after the diode. Does that sound right? I have gone through the check that Orion recommended which was to pull the current sensor to see if the BMS responded and it did drop to zero volts. so full pack 5 volts and no pack 0 volts (.03v ) -- For every complex problem, there is a solution that is simple, obvious, and wrong. -- H.L. Mencken -- Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
