Hi Michael, Since this is a theoretical experiment, we might just as well focus on that theory and indeed, at first blush is appears that the theory says that if you have a closes course, your *potential* energy level is identical at finish as when starting, so there is no net build-up or release of energy other than the friction and kinetic energy, since any height gain or loss must be made up by the end of the trip.
However, an electric motor works different than an ICE. Where the ICE motor has a weird efficiency change (weirder for petrol as for Diesel engines and the Prius' Atkinson cycle is again slightly different than a regular petrol ICE) the efficiency of the electric drivetrain is in theory perfectly linear falling with the amount of power delivered, since losses go up squared with the current (force) delivered. Result is that if half the drive causes you to use double the current and half the drive you can maintain the speed downhill at zero current, your total *loss* will have doubled. It is 4x as large during half the drive, compared to the 100% level ride. So, in theory, diving over hills and mountains at the same speed should consume more power than driving the same speed and distance on a level road. In an electric drivetrain, loss may be at or above 30% at full throttle, while at half throttle it is typically at or below 10% for the same reason. So, the total energy difference is not very big, you may go from the energy consumed at level road to an increase of around 8% for the example drive half uphill and half downhill. (level would be 92% energy to the wheels, 8% loss, for the doubled loss in the hills you would have 16% total loss so the energy consumption rises by 8%) Hope this clarifies, 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 Michael Ross Sent: Wednesday, November 20, 2013 4:36 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] EVLN: Kia Soul EV goes global and aimsfor120-miledrivingrange Cor, this is really a theoretical topic. Why should a level ride be easier than a hilly ride if it is a circuit? I disagree about regen saving anything except when used for braking, then you are trading waste heat for some charging.. If you use regen to slow down on hills you are causing an inefficiency. If you are on a hill that is too steep for safe coasting and brakes must be used, then regen is better than heating your brake rotors. If you take all this out of the thought experiment, then hilly and level are equal. On Wed, Nov 20, 2013 at 7:22 PM, Cor van de Water <[email protected]> wrote: > Michael, > How often do you encounter a steep road that is completely straight in > the mountains? All the roads in the surrounding mountains that I know > have sharp turns, for which you will *definitely* want to slow down. So > except if you are in roller-coaster country, having regen will save at > least part of the energy from the downhill run when you need to slow > down for the next turn... > > BTW, it may be that the information is skewed due to the redefinition of > electric vehicle by some manufacturers. I have noticed that my Prius can > get better mileage going over a large hill than when doing a steady > speed in flat terrain. This is probably similar to the "Pulse and glide" > hypermiling technique. This has of course nothing to do with pure > electrics, but since GM calls their plug-in hybrid an EV, that may be > where the confusion comes from... > > Regards, > > 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 Michael Ross > Sent: Wednesday, November 20, 2013 3:51 PM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] EVLN: Kia Soul EV goes global and aims > for120-miledrivingrange > > I am not talking about regenerating. The net change in gravitational > energy is zero on a round trip. I am talking comparing level to hilly, > and > that is all. Drive around the circuit, go steady on the level course, > only > brake at the end,; on the hilly course, coast down hills so you don't > waste > on regenerating (there is inefficiency if you regen, but if you just > reduce > power or coast that is fine). There is no difference between level and > hilly - except - if you hit higher speeds going downhill you have more > wind > resistance. Change in SOC ought to be the same either way. > > I am not sure why you want to regen on the downhills... that will queer > the > deal. Regen for braking that is what is for. > > > > > > > On Wed, Nov 20, 2013 at 6:17 PM, rayfellow <[email protected]> wrote: > > > What I've heard is that amount of energy captured going down hill > (regen) > > results in power to the wheel of about 30%. There's power lost at > each > > step > > along the way - generating electricity, storage, release and then > power to > > the motor. The net result is 30%. > > > > > > > > > > > > > > -- > > View this message in context: > > > http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Kia-So > ul-EV-goes-global-and-aims-for-120-mile-driving-range-tp4666302p4666339. > html > > Sent from the Electric Vehicle Discussion List mailing list archive at > > Nabble.com. > > _______________________________________________ > > 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) > > > > > > > -- > Put this question to yourself: should I use everyone else to attain > happiness, or should I help others gain happiness? > *Dalai Lama * > > Tell me what it is you plan to do > WIth your one wild and precious life? > Mary Oliver, "The summer day." > > To invent, you need a good imagination and a pile of junk. > Thomas A. > Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > > A public-opinion poll is no substitute for thought. > *Warren Buffet* > > Michael E. Ross > (919) 550-2430 Land > (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google > Phone > (919) 631-1451 Cell > (919) 513-0418 Desk > > [email protected] > <[email protected]> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131120/e78a > f08a/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) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do WIth your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131120/5906 2773/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)
