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Re: 12V source for lighting

From:          es61@prism.gatech.edu (Eric Schumacher)
Subject:       Re: 12V source for lighting
To:            raf40@oes.amdahl.com (Richard Funnell)
Date:          Fri, 5 Jan 1996 11:09:04 -0500 (EST)
Cc:            quattro@coimbra.ans.net (Quattro)

I concur

Also, the voltage should not change much at the alternator, but the
amperage definitely will.  If the voltage varied that much at the
alternator, it would also vary everywhere else in the system and fry the
car each time you drive it.  Capacitors help regulate CURRENT, they should
have little effect on VOLTAGE.  

Eric Schumacher

> I will admit that I haven't actually tried both methods, but I find the
> argument about varying voltage difficult to accept.  There is a very heavy
> gauge wire connecting the two devices; at least on the urQ it is the same
> gauge as the connection to the starter.  The voltage variation you see on
> the voltmeter should be the same, within a fraction of a volt, measured at
> either the battery or the alternator.
> Richard Funnell,
> San Jose, California
> '83 urQ
> '87 560 SL
Capacitors and Batteries are not the same thing. They are
both energy storage devices. The capacitor stores energy 
in an electrostatic field on the inner surface of its plates. The
battery stores energy electro-chemicaly. The cap will either
store or release energy depending whether the cap's voltage is
greater or less than that of what is connected to it. Caps oppose
a change in voltage.  The battery's emf is determined by the 
the type of anode/cathode material, the terminal voltage is
different than the emf, since there is internal resistance in the
battery and associated voltage drops that are influenced by the
current flow in the battery circuit.


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