Re: Electrical Gizmos

[jlandry@domain.elided (John A. Landry)]

In a brilliant stroke of genius, tsm1@domain.elided (Tom Mandera) blurted out:

>When I start, the alt gauge doesn't move... I have to punch the throttle
>once, then the alt gauge swings to charge until it makes up for the starter
>effort.  I'm curious why it takes this throttle spike to "wake up" the
>alternator.. it'll then charge at idle *after* I hit the gas once.

This is because the alternator has a specific "cut-in" speed (non-technical
term), after which is begins to produce substantially higher output.  The
speed at which the alternator then cuts back out is lower than the cut-in
speed.  So the alternator will usually stay engaged once it's been speed up
past its initial cut-in speed.  Once the speed drops below a certain level,
it cuts back out again.

The output curve *might* look something like this (view in a fixed font)...


    |                     
    |                 * * * * * *
 O  |              *
 U  | Cut In     *
 T  |    |     *
 P  |    |    *
 U  |    |   *
 T  |    |  * 
    |     \*
    |    **
    |***____________________________
    0      1      2      3      4

           Engine RPM x 1000

John
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