Reason you can't drive as conservatively as you'd like is simply: other traffic. If you are alone on a 45MPH road, nobody cares if you want to do 35, but if 2 lanes of traffic are storming at you doing 55-60 then it is mightily inconvenient if someone is blocking the road at 35. The other reason of course is your own time. While it makes hardly any difference if you are doing 55 iso 60 on a freeway in time difference, you are still taking an extra 5 min on an hour trip and sometimes that means missing appointments, so a higher speed may be necessary at times.
BTW, I question the 85% efficiency. Not at max (acceleration) power, but I am under the impression that the majority of the driving is not done at max acceleration and at lower power levels, the efficiency of the drivetrain is usually higher. For example, doing a constant 55 on a flat freeway takes only 15kW while max acceleration is about 6 times that amount. 15kW is about 40 Amps while max current is either 200 or 250A depending on the vehicle. Running at 20% of max also means a Voltage drop of 20% so resistive losses drop to 4% of max losses when running at 20% power, so I presume that if max losses are 15% (=85% efficiency) then the losses at 20% must be much lower, as long as the *fixed* losses are orders smaller. Cor, happily regenning before every traffic light that is not green and for sharper turns. On Tue, Jan 4, 2022 at 3:04 AM EV List Lackey via EV <ev@lists.evdl.org> wrote: > > On 4 Jan 2022 at 22:40, Bill Dube via EV wrote: > > > Whatever the drivetrain losses, they at least double when you > > regeneratively brake. > > I see your point, but I think it's a bit academic. Assuming your 85% > efficiency number, you aren't losing 30% on regen, you're losing 15%. > You've already spent that other 15% by the time the energy gets to the > wheels, so it's gone anyway. And 15% loss is a lot better than the 100% > loss that you get burning it off in the friction brakes. > > > If you drive a bit more conservatively, you can avoid expending that > > energy extra energy in the first place, > > Here I agree with you completely. Not using the energy in the first place > is better than using it and then recovering some of it. Unfortunately, you > still have to use energy to move, unless your trips are all downhill. :-) > > My point is that regen id like partly smoothing out the hills and valleys. > With good strong regen, properly used, your energy use for a given hilly > route is only slightly more than if it were flat. > > If you're not in a hilly region, I agree that regen is of less value. But > as you say, with modern controllers, you get it essentially free, so it's > always worth including and using. > > One other often forgotten benefit of regen is that it reduces friction brake > wear. That not only saves you money, it has environmental benefits in > reducing vehicle particulate emissions. > > David Roden, EVDL moderator & general lackey > > To reach me, don't reply to this message; I won't get it. Use my > offlist address here : http://evdl.org/help/index.html#supt > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > We don't devote nearly enough scientific research to finding > a cure for jerks. > > -- Bill Watterson, "Calvin and Hobbes" > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/ > LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/ LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
