Re: conversion is quite efficient..... - Saab General Bulletin Board - Saabnet.com
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Re: conversion is quite efficient.....
Posted by Reality (more from Reality) on Thu, 14 Jun 2012 19:38:28
In Reply to: conversion is quite efficient....., Mark from Toronto, Thu, 14 Jun 2012 15:48:29
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Less than half the vehicle's kinetic energy can be turned into electricity (before storage) in typical regenerative braking, because:
1. Regenerative braking can only be used on driven wheels;
2. Regenerative braking can not be used at very low speed, because there is not enough braking force to stop the vehicle;
3. Regenerative braking can not be relied upon when significant amount of braking force is called for either, because the drive train power capacity is much much less than the braking force that can be applied by the tire contact patch, and the electrical part only accounts for a small percentage of the drive train in a typical hybrid. It would be quite absurd for a car to take as long to do 60-0 as it does for 0-60; would be ploughing through people with that long of a braking time. Not to mention typical hybrids' best 0-60 is achieved with help of ICE not on electric motor alone.
After that half is cut out, we are looking at what is essentially a system comparable to an alternator for converting mechanical energy to electric energy, only the range requirement would be even wider / more hostile than the typical alternator. The typical alternator has an efficiency of 50-62%
Lithium battery charging efficiency is 80-90% under the most ideal conditions. In-car application certainly is not ideal. Let's take 80%.
Lithium discharging efficiency is 80-90% under the most ideal conditions. In-car application certainly is not ideal. Let's again take 80%.
Other types of battery typically have lower charge/discharge efficiency. NiMH battery charge/discharge efficiency is around 66% each way. So giving 80% for each is rather generous, considering that up to this point most hybrid electric car models on the market with Lithium batteries face fire threats (Volt and Karma)
Then finally the electric energy is used to drive wheels again, so after drive train losses, let's say again 80% efficient. So let's tally Up
50% x 50% x 80% x 80% x 80% = 13%
posted by 75.67.1...
Posts in this Thread:
- 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 <-- Viewing This Message
- 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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