Yes I see your point regarding starter motors on the crankshaft - many piston engined aircraft engines have the starter in the propellor boss and start the engine at high revs. The major drawback with this option is the very high current draws from the battery that this will entail and the problems of recharging such a draw will require.

The second point regarding altenator speeds is not so clear cut - as the altenator is currently driven, in the vast majority of vehicles, from the crankshaft by a belt and pulleys you can actually gear it to run above crankshaft speed should you wish to, once again very few manufacturers have chosen this option

I understand
Sorry

It's the size of the thing, they are gigantic. You can imagine the size of the thing bolted directly to the crank having to turn the engine over. That's where the idea of generating 42 volts come from.

I think that the starter on the end of the crank will happen on a big scale, emissions will drive the issue.
Alternator as well? Personally, I think so just on the grounds of economics alone. You might as well make good use of those large windings and magnets and ditch the stand alone alternator. You could generate 12/24 or 42 volts and put a whooping charge to the battery or batteries. Another member of the failed FL2 clutch/DMF club, twice.

If you put 42 volts into a 6 cell lead acid battery, it may require frequent topping up with distilled water....

Citroen dabbled with a starter alternator in the late 90's, (last time I went to the motor show), dont know if it ever came to production, tis a good idea and could also be a regenerative brake in a hybrid vehicle (which are not) At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

Combined starter/generators were not unknown in the 1930s/194040s (I think Clement Talbot used them).

In some ways a good idea but with the rev range of modern engines it would be a significant amount of weight wizzing around at great speeds. Maybe you could do away with the flywheel and build a DMF device into the starter/generator!.... be easier to fix.  John
07 HSE Narvick Black
Land Rover Series One
Triumph Rocket 111 (sadly gone!)

Don't even think about it

Can you imagine the bill when you "fry the clutch" as opposed to actually it's not fit for purpose but we're bigger than you so

Rather than a friction plate and pressure plate - which several parts suppliers could manufacture, its new generator and clutch £3,000?


That will have you buying sensible autos in your droves  Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Plenty of stop start today for me and the outside gauge reading never got above 1, let alone 4 (must check if the handbook has changed from earlier extract in this thread).

"Eco" on the dash display comes on when the engine is stopped; light on the Eco switch on the console is on when selected even if not actually operating

Stop-start did not work for quite a while after cold start. Gone... 2013 XS TD4 Manual Firenze Red
Gone... 2008 (09MY) XS Td4 Manual Stornaway Grey
Prior... 2003 G4 Discovery 2, 1998 Disco 1 and 1997 Disco 1 Company car before that
Also gone in Nov'13, after 7.5 yrs, to new owners with time for more TLC - 1980 Series III 88
Current 2015 Discovery Sport HSE 2.0

Eco Stop/Start works down to 0 degrees C