RE: '86 C-GT Alternator repair?/short in system? (long)

[Aleksander Mierzwa <alex@matrix.com.pl>]

Allan wrote:

	>	I have a discharged battery and it will not hold a
charge. The car
	>showed signs of losing its charge over a period of a day or two
and then
	>died. I_can_jump the car and the engine_will_idle and rev
showing
	>no_battery_idiot_light and showing a_reading_of_13 on the
digital volt
	>display. But after shutting down, it will not re-start. Before
jump,
	>there is nothing but a very_dim_battery_light and there is
no_digital
	>dash display and no reading on the lower gauges(volts/oil temp)
at all
	>until a few seconds have passed with the key in the start
position, and
	>then digital display comes on and a reading of only_8 volts
shows up on
	>the gauge. So battery is very low and does not hold a charge.
Alt.?
[...]

Allan, one can think of three possible causes of our problem:

1. Dead battery ( most likely )
2. Bad alt
3. A short in the electrical system causing battery to discharge quickly
or an open circuit/bad ground between alt and battery

>From what you've described your alternator is probably working OK. Try
switching all major electricity receivers with engine running.
Headlights, AC, rear window defroster. Are your headlights bright? Or do
they dim at idle and get brighter when you rev the engine? If your car
seems to operate properly with the engine running, your alternator is
OK. Now the battery. Did you try charging your battery from an external
source? I would recommend to charge it overnight with a battery charger
( with the battery disconnected from the car ), wait another 24 hours or
so and then try to start the car - preferably not your car ( we want to
exclude the possibility of major short causing your problems ). If the
car starts, your battery is good ( or at least good enough to hold
charge for 24 hours ). If both the alternator and battery prove to be
OK, check the wiring. Don't overlook the obvious, are the battery clamps
free of oxidation? What about the ground strap? If you still can't find
the problem, have the electrician check the current draw ( or do it
yourself if you have suitable amperometer ). Good luck!

						Alex