On 20 Oct 2015 at 19:34, Mike Nickerson via EV wrote: > I've seen 20A circuits, but only in commercial installations.
You'll see plenty of 20a branch circuits in homes - all newer homes are wired this way - but 20a receptacles on them are indeed pretty rare. This is because the code has an exception allowing cheaper 15a-rated receptacles on a 20a branch circuit, as long as there's more than one outlet on the circuit. If there's only one receptacle on the circuit, it must be a 20a-rated recept. (Code experts argue over whether a duplex receptacle counts as one or two outlets.) IIRC, the code ALLOWS but doesn't REQUIRE 20a-rated receptacles on a multiple-receptacle 20a branch circuit. I installed 120v 20a recepts on the branch circuit in my garage to allow for better EV charging, though I'm not 100% convinced that (once you're beyond the 50 cent bargain bin junk receptacles) there's much difference between the guts of a 15a-rated recept and those of a 20-a rated recept. One more note about this. Because code limits sustained load on a branch circuit to 80% of its maximum, you can charge at no more than 1920 Watts from a 120v 20a residential branch circuit. If your EV gets 250 Wh/mi and has a typical 80% charging efficiency, you gain just over 6 miles of range per hour of charging. If you sleep 8 hours and charge while you sleep, that's 48 miles you can drive per day. It could be more than that, since some switchmode chargers do better than 80% efficiency. Also, staying below 80% SOC increases battery charging efficiency. But that's a pretty good rule of thumb. You're much better off going with a 240v circuit and charger. A 240v 20a circuit gives you 3840 Watts, for over 12 miles of range per hour of charging - 96 miles overnight. A 50a range / welder circuit is an even better bet, as long as your charger has the guts to use it. That recept allows 9.6kW charging. At that rate the EV described above gains over 30 miles of range for each hour of charging - about 245 miles overnight. 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 Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
