Regenerative braking can only recover a very small percentage of the total kinetic energy of the vehicle, because:
1. Regenerative braking is not operative at very low vehicle speed; conventional brake pads have to be used in order to make the vehicle stop;
2. Regenerative braking is only available on driven wheels;
3. In braking where the braking performance is crucial, the braking force is matched to the maximum that the wheel contact patch can generate, which is many times the output of the typical drive train. In a hybrid, the electric motor/generator is only sized to be a small fraction of the total drive train output.
Counting on regenerative braking to provide the entire braking force is a little like using "engine braking" only without ever using the brakes. Not exactly practical if you don't want to be a serial murderer.
I was sloppy in the sample. The typical high traffic vs. no traffic driving is the not the mad driver making up the lost stop time, but instead the 30min of 1200rpm (360000Rev) becomes a one-hour drive like I initially mentioned before I gave the wrong time segments. That one hour will consist of 30min of idling at 800rpm, 28min of 1200rpm 30mph driving, and 2min of 3000rpm accelearation. The heavy traffic does not allow for high speed driving. Total engine rotation is 63600Rev, or about 75% more gas consumption for a trip that takes twice as long in time. That's the difference between 30mpg smooth highway driving vs. 18mpg stuck in city traffic. The long idling is what kills the gas mileage, and something that the hybrids help the most (cutting out 24000revs in this example).
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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