I gave 3 reasons why the kinetic energy available for recapture is 50% or less, what makes you assume I think 2 of the 3 are not contributing factors? The passive wheels take a cut into the energy available because they have brake pads there. If you are driving hilly route, rear wheel braking while going down the hill has to be non-trivial in brake force distribution because otherwise front wheel braking alone would spin the car in many situations.
Sure, I believe you drive up and down the hill, stop-and-go all the time, and never use more than 25% of your vehicle braking capacity, and hardly ever needing to coming to a full stop (regenerative braking can't do full stop on its own). Pigs fly too, and I was born yesterday.
Drive motors have to deal with even wider rpm range than the alternator, which is strapped directly to the ICE engine. That means, regeneration efficiency is probably comparable to and likely lower than alternators.
The 33-50% regeneration quoted for Prius further supports my contention. That's the first ratio, percentage of mechanical energy available for regeneration before it is turned into electricity, before it is stored in chemical energy, before converted back to electricity, before driving wheels again. In my earlier analysis, I assumed the upper limit 50% for this stage.
Where is your earlier assertion about 85% efficiency for the overall system coming from? Overall efficiency is the product (multiplication) of all stages, not average of all stages.
Regenerative braking technology is certainly not in its infancy. It has been used on railways since the 1930's. There, the percentage of energy available for recapture is much higher because the wheel friction on road surface is much less, and trains literally rarely have to come to an unscheduled full stop. Regenerative braking there is used to control trains going down hill for tens of miles (after having climbed for tens of miles). The energy captured there is often fed directly into the local electric grid because the trains run on fixed routes and are wired into the grid.
5kW gas turbine is still 5kW, or about 7hp. That makes for a car that can sustain a top speed of about 30mph, if that.
posted by 75.67.1...
Posts in this Thread:
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- On board the UK's first fast-charge electric bus, JohnA , Wed, 13 Jun 2012 19:31:04
- Tesla Model S: 'If Apple Made A Car, This Would Be It', JohnA , Sat, 23 Jun 2012 07:17:05
- Won't work. Steering wheel is on wrong side, Used to be Chaz, Fri, 15 Jun 2012 12:43:03
- Foreign Policy Mag photoessay on electrics, JohnA , Thu, 14 Jun 2012 06:39:11
- Neil Young - e-car tinkerer, JohnA , Thu, 14 Jun 2012 12:28:20
- Show me the batteries, JerseySaab , Thu, 14 Jun 2012 07:02:30
- I got yer batteries, No Snaab , Thu, 14 Jun 2012 17:02:34
- don't be a Luddite!, JohnA , Thu, 14 Jun 2012 07:10:11
- I like electric motors, batteries are the problem, JerseySaab , Thu, 14 Jun 2012 07:44:25
- don't be so gullible, JerseySaab , Thu, 14 Jun 2012 07:18:47
- Don't be so narrowminded, ELaw , Thu, 14 Jun 2012 07:45:08
- Re: don't be so gullible, Steve T., Thu, 14 Jun 2012 07:43:49
- EV vs hybrid, Snowmobile , Thu, 14 Jun 2012 07:41:59
- The one thing I don't get:, ELaw , Thu, 14 Jun 2012 08:02:58
- Re: The one thing I don't get:, Snowmobile , Thu, 14 Jun 2012 08:14:58
- Regenerative braking is grossly over-rated, Reality, Thu, 14 Jun 2012 10:03:09
- Very poor math....what about efficiency?, Mark from Toronto, Thu, 14 Jun 2012 12:40:28
- Re: Very poor math....what about efficiency?, Snowmobile , Thu, 14 Jun 2012 13:12:17
- More like 20-30% efficient, Reality, Thu, 14 Jun 2012 13:12:08
- at WOT only!, Siegfried, Thu, 14 Jun 2012 14:57:27
- and within a certain (and limited) RPM range, Siegfried, Thu, 14 Jun 2012 15:07:49
- conversion is quite efficient....., Mark from Toronto, Thu, 14 Jun 2012 15:48:29
- Re: conversion is quite efficient....., Reality, Thu, 14 Jun 2012 19:38:28
- Re: conversion is quite efficient....., Mark from Toronto, Thu, 14 Jun 2012 21:12:09
- Strawman tactic, Reality, Fri, 15 Jun 2012 03:46:58
- Think this out please...., Mark from Toronto, Fri, 15 Jun 2012 08:54:56
- Re: Strawman tactic, ELaw , Fri, 15 Jun 2012 07:00:41
- Strawman tactic vs Triple Strawman tactic, Snowmobile , Fri, 15 Jun 2012 06:27:37
- Say what??, ELaw , Fri, 15 Jun 2012 05:13:20
- apples and oranges, Siegfried, Thu, 14 Jun 2012 17:35:26
- Very good points..., Snowmobile , Thu, 14 Jun 2012 12:13:10
- Fuel consumption during idling, Kristjan, Thu, 14 Jun 2012 13:00:43
- corrected..., Snowmobile , Thu, 14 Jun 2012 12:44:11
- bah, I made the error, not you!, Snowmobile , Thu, 14 Jun 2012 12:21:49
- Correct but biased..., ELaw , Thu, 14 Jun 2012 11:43:40
- Yes, hybrids can be practical, JerseySaab , Thu, 14 Jun 2012 07:49:41
- eAAM, Snowmobile , Thu, 14 Jun 2012 08:03:07
- Re: eAAM, Mark from Toronto, Thu, 14 Jun 2012 21:16:30
- Turbo!, ELaw , Fri, 15 Jun 2012 06:06:04
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