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I agree with you that there are inefficiencies. The thing is you have assumed some specific kind of (albeit reasonable, but not exclusive) system and proceeded to knock it down.
I'm not going to call you on it other than that. I agree that many of the current popular offerings in the market mostly match what you are saying to some extent + so fair enough. I don't want to imply a perfect world + I don't want to say that the current offerings are necessarily good, or a smart buy in terms of $/value, etc.
What is more interesting to me is what might be achievable going forward, and this is why I keep bringing up that wheel motor example. I have no idea whether it will be viable in the marketplace (having 4 motors does increase cost + complexity + it really depends a lot on the design and manufacture among other things)... but, to address your "men"...
"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;"
iirc, PML (at the time) claimed that they do not need conventional brakes on their motors - they can optionally provide them as a parking brake or to satisfy manufacturer or government requirements but braking performance meets requirements without. The motor/generator is directly bolted to the wheel. Even if they did have a small pad in there we don't know about, the amount of energy going from 5mph to 0mph is pretty small compared to the rest of stopping from 40mph. The actual % lost there would depend on the lowest speed before applying friction (my 5mph was hypothetical).
"2. Regenerative braking is only available on driven wheels;"
4 wheel drive?
"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."
For the first half, see answer to 1, though you are correct that it does depend on the sizing of the system + weight of the car and it is more critical that 60-0 be fast than 0-60*. A hybrid can have any ratio of fuel/battery or EV/ICE... If one is using a small ICE as a generator to extend range it may only need to provide the cruising hp, which is surprisingly low if the top speed is limited (ie racing Bugatti Veyrons is out).
As to the other items, who said regenerative braking needs to recharge a Li-ion battery? Who said there needs to be a transmission or extended drive train? I agree that there are inefficiencies in the system. The trouble is you are trying to do a system budget for an adhoc/unknown/made up system with numbers that may or may not be accurate... so it's pretty easy to knock down... classic strawman...
* a little aside here: electric motors have very different torque curves than ICE... the torque spec for that mini was insane. something like 2000lb-ft of torque and it all switches on from 0... this was of course electronically limited + controlled (can you imagine the smoke + loss of rubber? ha!). This would go a long way in terms of improving stopping power. How much of PML's "specs" are unsubstantiated claims, I don't know, but it is an interesting idea... certainly the claims are very impressive. That we haven't seen much of the Mini being driven makes one wonder, but Volvo (and others) have worked with this technology, so there is something interesting there...
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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