There is no issue here. The OP brought up the continuous rating of the motor at certain RPM, which just says something about the ability to sustain a certain current at a certain speed indefinitely, but which does NOT limit the motor to that power, so accelerations (which by definition are not limited by continuous ratings anyway) are certainly possible at *much* higher power levels - as long as the current limit on the *controller* allows for them. Note that current limits *can* play a part in the acceleration, especially at lower speeds. My previous EV had a very low (250A) motor current limit, combined with 200A battery current limit. That was OK since it was a 312V pack, but the motor current limit caused the launch of the vehicle to be somewhat slow, but at modest speeds the acceleration picked up because the power to the motor continued to rise with increasing RPM (voltage on motor) so there is an effect of motor current limiting that affects the way the EV behaves.
Regards, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.com Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Peri Hartman via EV Sent: Saturday, July 26, 2014 3:37 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Hybrid Mustang: batteries Yep, areo drag is proportional to square of the speed: 1/2 * Cd * A * air density * speed^2 where Cd == drag coefficient (you can look this up for many car models) A == frontal area: the area of the vehicle as viewed in 2D from the front, in meters^2 air density = roughly 1.2 kg/m^3 at standard temperature and pressure. speed: in meters/second will give you the resistance (i.e. force) in N (newtons). Peri ------ Original Message ------ From: "EVDL Administrator via EV" <ev@lists.evdl.org> To: "Electric Vehicle Discussion List" <ev@lists.evdl.org> Sent: 26-Jul-14 2:23:20 PM Subject: Re: [EVDL] Hybrid Mustang: batteries >On 26 Jul 2014 at 8:24, Ben Goren via EV wrote: > >> At 55 MPH with the 4.11 is 3000 RPM; with a single AC-51, that's 22 >>hp. >> The single motor would be okay... At the slow end...1000 RPM is ~19 >> MPH. Five horsepower might not cut it by itself, and 15 MPH school >> zones might be a problem... > >IIRC, aero drag increases proportional to the square of the speed, and >it's >going to be pretty minimal at 15mph, no? So something just doesn't >quite >ring true here. > >In fact I've driven some pretty underpowered cars, DC EV, AC EV, and >ICEV. >I've encountered some that could maintain 15-20mph just fine, but could >barely (in some cases just couldn't) make 55mph. NEVER vice versa. > >David Roden >EVDL Administrator >http://www.evdl.org/ > > >_______________________________________________ >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)
