Oh and BTW, Ground leakage through a non-isolated charger and some leakage path (motor or battery pack or otherwise) or a bad Power Factor (no PFC) will make it impossible to charge from a J1772 compliant EVSE. (going back to the subject of this email chain)
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 Cor van de Water Sent: Wednesday, January 30, 2013 4:06 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Level-2 on-board charger off a J1772 Chuck, You probably measured 30 mA with the clamp-on Amp meter, 300 mA will *blow* a 7W 120V bulb. (as you need approx 600V to send 300mA through a 7W bulb because it has a nominal resistance of approx 2k Ohm) More likely - since it was glowing - it was colder and only 1k Ohm, which jives with the 30V and 30 mA figures. If you increase the voltage from 30V to 120V (In the worst case that the ground leak is on the end of the pack and the opposite end of the pack is grounded through an unisolated charger) then the current will increase with the voltage: 4x voltage, also 4x current: 120 mA instead of 30 mA. Indeed, these currents are above GFCI limits (and certainly above safe limits - I prefer to work on a pack that is clean enough that I can touch any connection without even feeling a current! I do have a 120V pack of floodeds myself, but I can touch any interconnection without trouble. Otherwise I would not feel safe working on (watering) the pack. 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 Chuck Hursch Sent: Wednesday, January 30, 2013 2:08 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Level-2 on-board charger off a J1772 On 1/28/2013 5:17 PM, Bruce EVangel Parmenter wrote: > [ref Elcon PFC-2500 thread] > > My S10 Blazer EV (with a 132VDC pack of 6V T145s) had metal battery > racks from its creation which were grounded to the chassis. In the 15+ > years I enjoyed the heck out of my EV conversion, charging and driving > anywhere and everywhere, I never had a GFI trip from leakage current > through the metal battery racks, whether I was charging using a: > > K&W BC-20 with a boost transformer for up to 144V > Zivan K2 or NG5 > Manzanita Micro PFC 20, 40, or 50 > +more I swear I have a memory of looking at your engine bay some 10-15 years ago, and it had polypro (or similiar) cases for the front pack(s). If you had metal racks actually touching the tops of your batteries, I would certainly like to know how you managed to avoid GFI trips through unisolated chargers. I had some occasional GFI trips through the K&W BC-20 with my first battery pack (1994-2001). However, with the liberal use of elbow grease, I was able to bring the voltage between the most + post and chassis ground close to zero. During my second pack, I lost being able to do that - it would never go down. By that time I had a Zivan K2 (isolated), so GFI trips were a thing of the past. Since then, even with re-powder coated racks done in 2009 at the beginning of this 4th pack I'm on now, I've never been able to drive the voltage down. I even installed something similiar to what ElectroAutomotive was selling in an isolation kit for the hold-down racks - it didn't make much difference, although I found it rather difficult to ascertain if I didn't have metal touching through the hold-downs. Well, it could be through motor carbon tracking, as Roland has often mentioned. One of these times I may crawl under the car in my apt. carport and disconnect the motor. I don't have a contactor on the negative leg of my pack - the VoltsRabbit didn't come with one. With visions of Lee watching over me (since I think he has explained this a few times in the past), a few months ago I decided to find out just what the magnitude of the chassis leak is that I have. I figured measuring through a high-impedance digital voltmeter can pick up a lot of phantom readings, since it is so sensitive. So I got out my "light table", which contains eight screw-in light bulb bases rigged up in parallel. I hooked up this light table through 6-ga cables to the most + post and to chassis ground. The first bulb I tried, a 300W incandescent, I figured wasn't going to do anything, since the chassis leak resistance would be too high to light up this bulb, but it was a starting point. Wound my way down through 60W and so on to try and find the "sweet spot". Well, a 7W/120V incandescent got me to the sweet spot: it was something like a 30V drop across the bulb at some 300mA as measured with a clamp-on ammeter. Bulb was barely glowing. But that's about the magnitude of my chassis leak. So I wonder can I just multiply that voltage by four and say at 120V I have a 75mA leak (which is way over the typical 5mA GFI limit) as concerns an non-isolated charger? > [snip] _______________________________________________ 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) _______________________________________________ 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)
