Jerome Yuzyk wrote:
>
snip
>So, this means that a single instrument failure can stop the car from
>starting. Hmmm...
I would guess that an Alpine has many "single point failures". If you started
with the electrical system you might have the following:
component failure mode effect
battery cell short reduced voltage, current
battery cell open no electrical power
battery case crack same a cell open
battery cable open no electrical power
battery cable short to chassis multiple cases: smoke,
heat, fire, battery rupture,
no electrical power
alternator open charging system won't work
alternator short to chassis same as battery cable short to chassis
and on and on..... because of the Alpine's limited fuse system there are many
component and harness failures which can render an engine inoperative. In
other systems (engine, fuel) there is a single fuel pump, a single fuel line
which if crimped or blocked can stop an engine. A single oil pump, and oil
pump bypass. The list, if fully completed, would probably be several pages in
length.
If one were to continue this process you might then add in the likely
probability of the failure mode happening. Take the following two cases: 1)
the engine has a single crankshaft, but the probability of a failure in the
crank (like it suddenly breaks in two pieces) is pretty low for most people's
uses (not true necessaily for racing). Case 2) there is a single oil bypass
valve which, if it sticks open, results in very low oil pressure AND the
probability is not very low. (it has happened to me)
Which brings us to the question at hand: the ammeter is a single point
failure, what to do about that. A solution is, as Tom wrote, to wire a shunt
switch across the ammeter. Whether you choose to do this or not depends on
how nervous you are about this happening to you. How probable is an ammeter
failure ? I have never had an ammeter failure. I am not familiar with the
Lucas design, but if it is like the design I am familiar with it consists of a
shunt wire in parallel with the meter movement. Although the meter may be of
modest reliability, the shunt wire ought to be pretty high in the reliability
arena.
Anybody out there have their ammeter fail and disable their electrical system
?
-Roger
.
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 10:36:00 CDT