I can assure you that the Model 3/Y Powertrain is way above 85% efficient. 85% might have been reasonable for a mechanically commutated DC motor, but even modern non-Tesla powertrains are better than that!
On Tue, Jan 4, 2022 at 3:27 AM Cor van de Water via EV <ev@lists.evdl.org> wrote: > 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 > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20220104/05448e62/attachment.html> _______________________________________________ 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