On 11 May 2013 at 11:19, Morgan LaMoore wrote: > I would expect the charger to have a bridge rectifier at its input, > preventing the charger from supplying power.
I'm probably missing something - I'm the EE dropout, remember - but I don't see how this would make a difference. The EV charger was presumably connected across the 240v line (standard US setup with a tapped 240v transformer secondary, the tap grounded, and serving as a return for 120v loads). The 120v drill charger was in one of the 120v legs. If the breaker in that leg opened, only 120 volts to ground from the other leg would be available. Now the EV charger has no return to the full pole transformer secondary, so it seeks a return to the 120v tap by whatever means it can find. That's through the drill charger. Now you effectively have two loads in series across 120v. The high current EV charger has a lower effective resistance than the low current drill charger, so virtually all the voltage goes to the drill charger and very little to the EV charger. If I'm analyzing this right, the EV charger probably shut down for undervoltage. Then it presented a higher effective resistance to the series circuit than the drill charger, so it "saw" a more normal input voltage (IIRC these PFC chargers will use either 120v or 240v), and tried to start. This cycle repeated, which would explain why Steve "[heard] the charger cycling up and down." Most drill chargers I've seen have been supremely stupid gadgets, often little more than a slightly regulated wall wart. I wouldn't expect something like that to be damaged by this - it wasn't getting more than 120v, it was just getting intermittent 120v. But maybe this drill charger had more than the usual smarts. I have a new- ish cordless drill with a lithium battery, and its charger does seem a bit smarter than most. So, I suppose that rapid input power cycling might scramble such a charger's "brains." Others with better engineering chops than I might address this. > It's also definitely a good idea to have the breakers ganged together > in a 240V setup. It's not just a good idea, it's the electrical code. Steve might in theory have a legal reason to go after the former owner of his new shop/house, but it's probably not worth 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)
