In article m, geolemon wrote:
Also, there is a lag time for caps too, and it is a function of the
load
across the capacitors terminals. That is why manufacturers recommend
you
locate the caps closest to the amps.

The amount of charge stored in a capacitor is huge. There's a reason
the
directions advise you to charge the cap through a resistor with the
engine running. You're not going to drain a 1 or 1/2 farad cap so
that
it can't deliver at least 12 volts with a car audio system.
Yes, there's some ESR in a cap, that does create some lag time.
But, bear in mind, this takes the capacitor down from being a
"theoretically instantanious" device, to a "realistically just almost
instantanious" device.
Contrast that to a battery, whose transient response is inherently
slow. Slow not only to charge, but to discharge as well.
And the transient response of a deep-cycle battery is inherently
slower.. an intentional design trade-off, in using thicker, more
warp-resistant plates in the battery. Takes abuse.. but doesn't
transfer the electrons as fast.
The rise time of a capacitor may as well be the "theoretical
instantanious", compared to the slow milliseconds it takes for a
battery to respond.

The only time lag for a battery to respond that I know of it
its temperature. When it get warm with current draw, its
able to produce more current.


Transient response of a battery compared to the transient response of a
capacitor.

Yes, the charge stored in a capacitor is huge...
But we are only concerned with the amount of charge relative to a drop
from 14.4v down to 12v, the lowest a capacitor will discharge to in a
car... how much current it can provide as it drops between those two
voltages.
*

Another downside on an alternator (besides the high expense,
possibility of it being largely ineffective without setting your
idle
speed north of 2000RPM,

There's no need to idle up. A quality alternator is rated for output
at
idle. Otherwise, you can just slap a larger pulley on the
alternator.

No, most need at least 1500 RPM.


*That's been shown not to be true, quite often.
RPM does affect current capability, and often the ratings are taken at
higher RPM's. Do your homework before buying - I'm not the only one to
suggest that for alternators.
[b]

and installation considerations that have been
mentioned) is the fact that a bigger alternator is a bigger drag
on
your engine... and it's a bigger drag all the time, not just when
you
need it.

Mostly false. I loads with current draw.

Wrong. An alternator only requires more torque when the demand placed
on
it increases.
[b]
Yes, the electromagnetic forces will increase, increasing drag..
but there's a no-load increase in drag as well. The upgraded
alternator is larger than the non-upgraded unit... not necessarily
in terms of chassis dimensions... [b]
A larger alternator is more difficult to spin, inherently.
Bigger
rotor, larger magnetic forces... they can really impact your
car's
performance, robbing horsepower.

Most aftermarket alternators are no larger in size than their
stock
componants. The difference is in the number of turns in the coil,
and

There seems to be some more misinformation about current draws. The alternator
provides virtually all current untill the voltage gets down to below 13 volts at which time the
battery starts pulling. It does not really begin to draw significant current untill it gets
in the mid 12.5 volts range. At high current such as with starting currents, it dips well
below 12 volts.