Keep in mind that if you have just gone up a long hill the motor and commutator will be hot and over-speeding it on the downhill run may still damage it even though the current is now low (or zero). I think it's probably best to keep the RPM in the safe range under the worst conditions rather than risk the expense of a damaged motor.
Lawrence Harris On Aug 5, 2014, at 12:46 PM, Dennis Miles via EV <ev@lists.evdl.org> wrote: > David, and others, the most fragile part, of a series DC motor, is the > commutator. And that is, because the copper segments are glued to an > insulating core. When the current is flowing, the segments heat up and > soften the glue, then they are subjecting to "lifting," away from that > insulating core, and causing problems with the brushes, resulting a need > for an extensive repair. But, with no (or very low) current, the glue > maintains its strength, and the motor can be spun to a higher RPM, without > damage. > > PS. added a new "You Tube" Link (Below) > > Dennis Lee Miles > > (*evprofes...@evprofessor.com <evprofes...@evprofessor.com>)* > > * Founder: **EV Tech. Institute Inc.* > > *Phone #* *(863) 944-9913 (12 noon to 12 midnight Eastern US Time)* > > *Educating yourself, does not mean you were **stupid; it means, you are > intelligent enough, **to know, that there is plenty left to learn!* > > * You Tube Video link: http://youtu.be/T-FVjMRVLss > <http://youtu.be/T-FVjMRVLss> * > > * NEW You Tube Video link: *http://youtu. be/Pz9-TZtySh8 > <http://youtu.%20be/Pz9-TZtySh8> > > > On Tue, Aug 5, 2014 at 5:25 AM, EVDL Administrator via EV <ev@lists.evdl.org >> wrote: > >> On 4 Aug 2014 at 18:14, Ben Goren via EV wrote: >> >>> He says it's okay to spin the motors faster than 8000 RPM so long as >>> it's not the controller that's sending the current to the motors that's >>> doing the spinning. >> >> I wonder why this would be. >> >> 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) >> >> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140805/05c618f3/attachment.htm> > _______________________________________________ > 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)
