Hi There
Mike, Sorry if I`m failing you here, though I`ve never been one
to give up (-:
Have I got this right........ the problem for you is that you have
difficulty in understanding the relationship of electrical to mechanical
loading ?
Is your thought that the engine is turning the alternator at a speed
relative to the engine therefore the alternator gets something for nothing
?
Screeching belts......... The belt screeches because it is unable to take
the extra loading, it will screech for as long as that is the case. Extra
loading can be increased by trying to accelerate the alternator at a given
load or by increasing the load, if the belt drive were in good condition
properly adjusted and the alternator was working within it`s expected
loading range, the belt should not slip. a slipping belt is one that is
destined to fail, the more it slips and screams the more it wears the
slacker it gets and on and on until adjusted, by this time its operating
surface has a polished appearance and more than normal tension is required
to stop it slipping, this results on further loading on the alternator
bearings and the engine output.......... It`s an efficiency kinda thing ?
I guess that there is an ideal temperature for a belt to work at and that is
unlikely to be at freezing point when the elasticity of the belt is greatly
reduced, though a belt manufacturer is likely to understand that his belt
will have to perform under maximum load in just these sort of conditions ?
When it is cold and the belt has to work hard from start up it seems simple
that working hard will make it heat up quickly to normal design operating
temperature ? Just think of those big cars with loads of accessories seat
heaters screen defrosters loads of headlights and the wipers clearing the
snow on a cold morning, those alternators place a large load on the engine
in a bid to keep it all running. or in the summer when the aircon cuts in
when the car is at idle in traffic !
So you are driving along at a constant speed say 30mph, to do this you hold
the throttle steady, you come to a hill, if you hold the same throttle
position you will slow down by an amount relative to the incline of the
hill.......Or you will alter your accelerator to maintain speed, altering
accelerator position will use more fuel+air to give a bigger explosion
within the cylinder to push the piston harder etc.etc. Now I know you will
have no difficulty with that ? So the engine has to work harder to get up a
hill and how much harder is dependant on how steep the incline is. So if
there is extra work to do more power is required ? It is the same for the
alternator, it has more work to do on a flat battery than on a fully charged
one the motive force for the alternator is derived from the engine, the
engine see`s the alternator as a variable load if the battery is fully
charged the load is light if it is flat then there is the maximum load of
the generators output on the engine. .
I dislike to involve formula or math, as they baffle many folk, me
included.(-: If we got you to pedal a bicycle that had a generator in stead
of a rear wheel and attached to that generator we had a 10 watt lamp the
power you would have to produce to light it at full brilliancy would be 10
watts that is say 1/74 of a horse power, now I am sure you could manage that
?
If I added another 73, 10 watt lamps you would never manage that, you may
be able to pedal a little though it would take the power of a horse to do
the job, the formula involved is approx. 746 watts +1 Horse Power (HP), Now
I sure don`t know what size of horse they used to determine this formula
though it sure as H*ll is stronger than most men. So I do not fancy your
chances at matching it head to head. look at it another way if you like, an
electrical standard size in the UK for an electric fire heating element is
1KW or 1000watts....... A horse does not have the power to bring that up to
full heat as it can only manage 746 watts.
Again there ways that you could generate more power even if you ain't as big
as a hoss, though talk of gearing and efficiency would cloud the issue.
A simple test is to have your engine running and warm at idle watch the rev
counter, if you switch on as much electrical load as possible it will slow
down, because it has more work to do. Were there a means of generating any
amount of electricity with the output having little or no relationship to
the input, the laws of physics would have to be re written, and If I knew
how to do it, I`d be a real happy chappy, something for nothing or near to
it is an ideal I cherish as a Scotsman (-:
Don, If you feel I`m perhaps talking rubbish, jump in....... I come here to
learn. though I stress, I`m all for keeping it simple.
Cheers, George.
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