#387 of 395 ... Some Hands on Explanations by roland3

Feb 21, 2007 (8:22 pm)

#388 of 395 Would love to have theopportunity to try this myself... by lensman

Mar 21, 2007 (4:07 am)

I will try and post a sane distillation of whats in my head!
 
I know the major thing holding back all electric vehicles per se is battery technology, we can't get enough juice for the given size/weight to make an electric car go the distance we would want out of a family car (what about 350 miles on a tank) I also know that even the latest li-poly batteries still take a while to charge...
 
I also know that if we all made a slight change in our driving habits and if our workplaces would provide sockets for charging your car whilst at work and our respective governments help put in place the infastructure for charging your car at home(I live in an appartment without a garage, so running an extension cord out to the car would get me loads of more headache ) we could all live with and love the current best of breed electric cars (tesla roadster is an example of the right technology, but, the wrong application for most of us)
 
That said I also think a better more gradual change involves, hybrid cars that still run on petrol, but, eek out the most efficiency out of the fossil fuel and as a by product lower emissions drastically. Which brings me to the meat of my post, Ive posted some of this here before, but talked about a diesel engine powering a generator that charges an onboard battery and drives an electric motor that drives the wheels (a serial hybrid). I realise that by adding the conversion from fossil fuel to electricity and storing most if it then converting it back to motive power to the wheels involves a few losses of efficiency. But really how much are we talking here?
 
Im going to make some assumptions here: (these are not based in fact, just my guess)
Typical motor electricity to motive power efficiency: 85-90%
Typical generator motive to electricity efficiency: 80-90%
 
So a simple scenario where we replace the drive train (gearbox, clutch, drive shafts) with a generator coupled directly to our gasonline engine, which then powers a motor driving the wheels, would net us a lower estimate of about 68% of the engine output (85% * 80%).
 
With the original clutch/gearbox in place I know you lose some of the engine power too, what is this roughly, about 10-15%? Would this electric drivetrain be any lighter than the equivalent mechanical drive train(gearbox, clutch) I know drive shafts would be needed for the electric motor too, but with in wheel motors being talked about this too might not be needed!
 
How much loss in efficiency in using this electric drive train are we a talking about over the mechanical drive train? My of the top of the head guess would put it about 20%.
 
Now couldnt this be efficiency loss be made up in using a smaller lighter gasoline engine (3 cylinder, lean burn, 1-1.5 litre capacity) that has been tuned to run at a higher rpm with turbo charging if necassary?
 
Wouldnt focusing on a smaller lighter more efficient gasoline engine that dont need to provide a wide power band, just a very small highly efficient band of power producing electricity to power the motor. (you could even include some ultracapicators that could soak up the excess electricity produced if the car is moving too slowly for amount of electrical power the gasoline engine/generator combo is producing and if you were to use regenarative braking, this could then be used to provide extra power to the motor when needed, or when restarting the gasoline engine if its been shutdown)
 
Sorry that this post is long, but, Im fascinated by all of this, should have been an engineer instead of the desk bound computer programmer that I am !!!!
 
Any ideas, criticism is welcome as is any kind soul that can point out any huge holes in my understanding or concept.
 
Its all gone very quiet on this board of late!

Replies to this message:

• roland3 (Mar 25, 2007 7:55 pm)

#389 of 395 Re: GM Expertise in Diesel Hybrid transit [toyolla2] by toyolla2

Mar 21, 2007 (2:38 pm)

Replying to: toyolla2 (Nov 25, 2006 10:05 pm)

#390 of 395 Re: Would love to have theopportunity to try this myself... [lensman] by roland3

Mar 25, 2007 (7:55 pm)

Replying to: lensman (Mar 21, 2007 4:07 am)

#391 of 395 PHEV diesel !! Cool !! Go DC !! by larsb

Mar 27, 2007 (6:39 am)

#392 of 395 Hybrid-Atkinson by transpower

Mar 31, 2007 (9:14 am)

#393 of 395 Long Trip Fuel Economy by transpower

Apr 07, 2007 (9:21 am)

#394 of 395 A-B-O-U-T D-A-N-G T-I-M-E !!!!!!!!!!!! by larsb

Jun 13, 2007 (6:23 am)

#395 of 395 Another update on the Peugeot 308 by larsb

Aug 29, 2007 (8:27 am)