scootz
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| posted on 23/12/08 at 07:57 PM |
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Running Alternator Off Half-Shafts
Saw this on a Formula racing car at the weekend... is there any benefit (other than space-wise)?
Does the 'normal' Alternator to Pulley assembly sap more engine power than driving the same Alternator off the half-shaft?
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blakep82
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| posted on 23/12/08 at 08:00 PM |
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mmm all well and good on a race car i think which is constantly moving, but imagine being stuck in traffic, like i was in the floods on friday nite,
took me 2 hours to move 2 miles, with that progress your battery would be dead i think
my car kept overheating....
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scootz
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| posted on 23/12/08 at 08:03 PM |
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Ah... good point!
I'll get me coat!
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blue2cv
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| posted on 23/12/08 at 08:07 PM |
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You'll probably find that the alternater on driveshaft trick is an easy way to get over the problem of extra battery drain (inj pumps etc) when
using the racers total loss electrics
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DIY Si
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| posted on 23/12/08 at 08:08 PM |
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Also, good luck getting the gearing right for it! Would you want peak voltage at 30, 40, 60, 100 mph?
Either way, not a brilliant idea unless racing. Even then, you might get away without running one at all!
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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rusty nuts
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| posted on 23/12/08 at 08:17 PM |
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If space is a problem it may be possible to run a drive shaft from the engine to drive the alternator like the Focus diesel?
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britishtrident
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| posted on 23/12/08 at 08:26 PM |
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I am pretty you will find it was fitted purely to satisfy the scrutineers --- it must have been running in a class that required a generator to be
fitted.
Most single seaters run toothed belt water pump drives (idea is the pump turns more slowly to reduce the drive power required and reduce cavitation)
which make driving an alternator in the conventional postion difficult.
In the old days you used to see cars in some classes with a bicycle dynamo (unlikely to actually be connected of course) that could in theory be
swung down to run on the outside of the fan belt 
[Edited on 23/12/08 by britishtrident]
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JoelP
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| posted on 23/12/08 at 09:14 PM |
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quote:
Originally posted by DIY Si
Also, good luck getting the gearing right for it! Would you want peak voltage at 30, 40, 60, 100 mph?
Either way, not a brilliant idea unless racing. Even then, you might get away without running one at all!
Wouldnt the regulator sort that out, to regulate the voltage?!
within reason i mean, obviously you'd have to make it spin a lot faster than the driveshaft.
[Edited on 23/12/08 by JoelP]
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Canada EH!
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| posted on 23/12/08 at 09:24 PM |
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They used to do that in NASCAR, but now with all the fans and pumps for brake and driver cooling the small alternators that ran off the drive shaft
are not adequate. They mounted the alternator on a bracket off the differential. It would be hard to keep the belt on the pulley on a half shaft, more
up and down movement.
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ss1turbo
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| posted on 25/12/08 at 11:35 PM |
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I'm thinking that driving an alternator off the drivetrain would be more power sapping - as it would take the same amount of power to drive it,
but you're adding your transmission losses as well. May be only a few percent, but most of the time those last few percent of power from the
engine cost the most.. OK we're only talking Watts for power (say 50, 0.05kW), but that could thoertically mean the difference between 1st and
2nd in a race..
Long live RWD...
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