On 24 Jun 2015 at 10:56, Lee Hart via EV wrote: > This creates a ground fault, and the GFCI turns off!
Clever! I wonder though how a household GFI would handle thousands of cycles. They're designed to be tested once a month (does anyone actually do that?) and to shut off a few ground faults. But then, they're pretty cheap to replace. I'm not an engineer (and Lee is), but here's an early draft of the circuit I used to shut off a 24v charger for my Electro-Ped. http://evdl.org/images/charger_shutoff_24v.tif By posting this I am laying bare my utter ignorance of electronics (I'm a EE dropout). It's been a long time, but I vaguely recall starting with a basic charger control circuit, probably from one of the Mims books, and hacking until I had something usable. I also apologize for the crude drawing and lack of detail; it's from my notes of the time. I haven't yet found the final drawing, sorry. Maybe I gave it away when I sold the Electro-Ped. I used this with a Dayton 12v / 10a battery charger I'd modified by replacing the push-pull rectifier with a bridge, and adding a regulator. I set the regulator so that when the battery reached 28.6v, the current was ~C20/50. I then calibrated my circuit to shut off the charger at 28.6v. I used this for about 5 years, and it did OK for me. The points marked "chg" are in series with the original charger's transformer primary. The transformer, bridge rectifier, and filter cap shown are a separate power supply just for my circuit; I think I actually used a 12v wall wart from my junkbox. The circle with an R in it is a generic regulator IC, probably 12v. The pot looks like 20k (?). The relay is probably 12v, SPST. The Start and Stop switches are momentary contact NO. IIRC the transistors were items from my junkbox; I think probably any switching transistors of sufficient current capacity to drive the relay would work. It's pretty crude, but maybe you can use it as a starting point. I guarantee that you can improve it. ;-) David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ 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)
