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If I had to guess, I'd say it's probably a bad battery. If you can jump-start
the car and the alternator light doesn't illuminate while the engine's running,
that's a good sign that it is indeed the battery. However if it was me, I'd
probably follow these steps to verify:
Fast test: jump-start the car. With the engine running, turn on one of the
interior lights. Note the brightness of the light. Turn off the engine. If
the dome light dims at least a small amount, the charging system is probably
working, and the problem is probably a bad battery (although it's possible it
might be a bad connection).
More exhaustive test; for this you'll need a voltmeter:
(1) Measure the battery voltage by putting the probes directly on the center of
each battery post (to eliminate any drops caused by bad connections). Have a
helper try to crank the starter while you're measuring. My guess is that the
voltage will either stay right around 12.6 volts (indicating a bad connection -
go to Step 2) or will drop *way* down to 8 volts or less (indicating a bad
battery or bad charging system - go to Step 3).
(2) If you've determined in Step (1) that you have a bad connection, move the
probe that was on the negative of the battery to a bolt or some other metallic
point on the engine or car's chassis. If the voltage is now noticeably below
12.0 volts while the starter is engaged, then there's a bad ground connection.
If it's still 12.6, try moving the probe that was on the battery positive to
one of the screws on the positive battery terminal; again if it drops, the
positive battery terminal connection is flaky.
(3) If you've determined in Step (1) that the battery or charging system is
bad, try to jump-start the car. If that succeeds, at least we know that your
starter and its associated wiring are probably OK. Keep the engine running,
disconnect the jumper wires, and measure the battery voltage again. If the
voltage drops below 12.6 volts, then your battery is not being properly
charged. (If the engine stalls when the jumpers are disconnected, then it's
*definitely* not being charged!) That could be a bad alternator, or a bad
connection going to the alternator. However if the voltage is 13.5 volts or
higher, your charging system is probably OK and the problem is a bad battery.
If the voltage is right around 13 volts, that's a tough call, but I'd still
blame it on the battery. In that case, you should probably drop the bucks for
a new battery, and measure the charging voltage with the new battery installed.
Note that even if the problem is with the charging system and not with the
battery, the battery might be damaged by being so deeply discharged so you may
want to be prepared to replace that pretty soon too.
Good luck,
- Bob T.
Konuas wrote:
> I think my battery has gone dead on me. When i go to start the car, the
> lights on the dash are dim and after trying to start the car, the clock
> reset to 12:00...
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