This analysis is missing something when it implies that more and more energy is recoverd when more and more stops are made along the same 10 miles. This is voodoo economics. Yes, the perecentages of energy recovered go up but there is no mention of how drastically the total energy goes up with the more and more stops.
I could drive with one foot on regen and one on the acceperator continuously and maybe force 30% recovered energy, but at a huge overall loss. Bob -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of Al via EV Sent: Saturday, November 08, 2014 11:02 PM To: tomw; Electric Vehicle Discussion List Subject: Re: [EVDL] Range vs Speed Nice explaination Tom. Al ----- Original Message ----- From: "tomw via EV" <[email protected]> To: <[email protected]> Sent: Saturday, November 08, 2014 10:36 AM Subject: Re: [EVDL] Range vs Speed >I looked at the effect of acceleration and deceleration rates on energy >used > per acceleration-deceleration cycle a while back. To simplify the > calculation I assumed the same rate for acceleration and deceleration. > You > do get more energy into the pack stopping faster with regen. For example, > at a faster deceleration rate, 6 mph/sec, 7.7% of the vehicle K.E. is lost > to work against drag and rolling resistance forces, and at a slower > deceleration rate, 2 mph/sec, 23.1% is lost. If you assume a combined > motor/controller loss of 20% and drive train loss of 10%, then for the > faster deceleration rate 100 – (20 + 10 + 7.7) = 62% of vehicle kinetic > energy goes into the battery pack, and at the slower deceleration rate > 100 – > (20 + 10 + 23.1) = 47% goes into the battery pack. > > However, you don't get a lot of difference in energy into the pack as a > percentage of total energy used when considering a trip with travel at > constant speed and a number of acceleration-deceleration cycles. For > Example: > > (1) My car accelerates at 6 mph/sec to 60 mph, drives 10 miles, then > decelerates at the same rate to a stop, estimated percent of total energy > used that is regained with regen is: 2.7% > > (2) Acceleration at 6 mph/sec to 35 mph and deceleration at same rate 10 > times in 10 miles: 12.7% > > (3) Acceleration at 6 mph/sec to 35 mph and deceleration at same rate 20 > times in 10 miles: 20.7% > > At 3 mph/sec, or 1.34 m/s (0 to 60 mph in 20 sec). Then the same three > scenarios give 2.4%, 12%, and 20%, so a factor of 2 slower rate doesn’t > change the result that much. At 2 mph/sec acceleration/deceleration rate > the > three scenarios give 2.2%, 11%, and 19%. > > Increasing total miles traveled, d, to 30 in scenario (1) gives 0.9%. > Increasing stops in this scenario to 3, with 30 miles total, gives 2.7%. > > Increasing vehicle mass increases the percentage of energy recovered, but > it’s a small effect for larger number of stop/starts. For example the > first > scenario goes from 2.7% to 3.8%, second goes from 12.7% to 14.7%, third > goes > from 20.7% to 23.2% if vehicle mass is doubled. > > Decreasing losses in the motor/controller and drive train of course > increases the energy recovered. For example, decreasing motor/controller > loss to 15% in scenario (2) increases the energy gained from 12.7% to > 16.5%. > > > > > > > -- > View this message in context: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/Range-vs-Speed-tp4672366p4672477.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) > > _______________________________________________ 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)
