Lee, this even works remotely without control wires, brilliant. Please note that you should adjust the "ground fault resistor" value based on the current that the GFCI detects. In Europe the standard household GFCI is rated for 30mA so the typical test resistor value there is 7k to create more than 30mA at the 230V nominal outlet voltage. If you use a 20mA detecting GFCI in the USA, you need a resistor not bigger than 5k6 to detect the current at the 120V nominal outlet voltage. Note that this resistor can get hot and even burn out if your GFCI fails to trip.
Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of Lee Hart via EV Sent: Wednesday, June 24, 2015 8:57 AM To: damon henry; Electric Vehicle Discussion List Subject: Re: [EVDL] Voltage sensing shut off switch damon henry via EV wrote: > Has anyone ever made a circuit to shut off a switch once a > predetermined voltage limit has been hit while charging. I would love > to work on something small that is easy to carry. It would plug > directly into a standard Nema 15 120 volt 15 amp receptacle and have > it's own Nema 15 receptacle for a charger to plug into. It would have > a voltage sensing input I could use to monitor my pack voltage and > once a predetermined voltage limit was hit, the circuit would open and > latch so that the charger stopped charging until everything was > manually reset. I'm sure there are a million simple ways to get this > done. Yes; this is indeed an easy problem to solve. :-) Charge your EV with an extension cord with a built-in GFCI (Ground Fault Circuit Interrupter). Or, put a GFCI in an outlet box with a male plug on the back and the female socket (that's part of the GFCI) on the front. The circuit that senses pack voltage will generate a ground fault, which orders the GFCI to turn off. It looks like this (here comes some bad old ASCII art -- view it with a fixed-width font like Courier): pack+___. . . ____/\/\___ . . . . . . . . . . . . . . . . . . . \/\/\/ | . R2. . | . . . . . . . . . . . . . . . . R1 1K . ^ . .| . 1K. ._|_/ D1 one or more zener diodes that . trimpot |____|. . . .//_\ . . add up to a few volts less your . to adjust voltage . . .|. . . desired turn-off voltage . where it switches . . .|_ . . . . . . . . . . . . . . . . . . . . _|. K1 a small relay with a . . . . . . . . . . . . . _|. 5-12vdc, 10-20ma coil. It . . . . . . . . . . . . . _|. will pull in at about 2-5vdc. pack-____________________| AC hot_____/\/\____||____AC ground . . . . . . R3 . . || . . . . . . 10K. . K1's normally-open contact The dots are just there to keep smart-alec email programs from replacing multiple spaces with a single space. If you can't figure out how to view anything with a fixed-width font, the circuit is very simple. It's a trimpot R1, a fixed resistor R2, a zener D1, and a relay coil K1 all in series. When the pack reaches the desired shut-off voltage, the zener conducts, current flows in the relay coil, and it pulls in. The normally-open contact of K1 closes, connecting R3 from AC hot to ground. This creates a ground fault, and the GFCI turns off! -- The greatest pleasure in life is to create something that wasn't there before. -- Roy Spence -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ 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)
