<SNIP>

Sounds like a battery problem but any good service station can do a
quick analysis to see that your alternator and regulator are working
well. I don't see much point in investing in a charger.

Chuck Fiedler

It sounds like a bad battery. I never even saw this sort of failure before
about 1980, but since then I've seen a bunch. The symptoms (if I'm
understanding yours right) are caused by a broken internal connection at one
terminal of the battery. The shadetree test - that's what I use most of the
time - is to turn on the headlights and watch them inbetween whacking the
battery posts with a hammer. No kidding! A modest whack, like cracking a
Brazil nut, will often jam the connection together. Being made of lead and
kept out of the air, the connection temporarily welds itself together
because of the headlight current and the lights come on. A better check is
to measure the actual voltage on the battery posts while doing the same
tests - any rise, even a volt, means a broken connection in the battery.
Hammering on a good battery doesn't make the voltage rise :-)

The other possibility is that the alternator is not charging. I imagine the
"battery" light has not come on. That leads to a quick test for the most
likely (and one of the least expensive) alternator failures: worn out
brushes. Turn the ignition switch to the "run" position so the warning
lights come on. The battery light should also be on. If not, the brushes are
not making contact. Brushes usually last about 150K miles - I don't know
what your odometer is. The brushes are part of a regulator assembly that
screws to the back of the alternator, making the repair quick and easy. I
paid $35 about ten years ago for a replacement regulator assembly so I
imagine they are $50 now. RockAuto.com lists the brush set (p/n GB299 by
Standard Motor Products) individually for $2.13, but the brush set can be
hard to find locally.

In any event, rather than buying a charger that - God willing - you probably
won't use again, most auto parts stores will check the battery and charging
system operation for free. I'd be inclined to replace the battery anyway
because if it is not intermittent (replace battery anyway) it has been
completely discharged a few times. Car batteries don't survive that very
well.

Mike

Well the battery is probably bad at this point too, but I would definitely
look at the charging system. Anyone with a volt meter can easily tell you if
that's working, if it's not, usually the brush pack/regulator in the
alternator is shot, the brushes do wear down over time.

Patricia,

I know you're not a mechanic, but you may feel a little more comfortable
about driving if you can deal with emergency situations. First off, you need
a set of jumper cables. The longer the better. They'll let you get a jump
start from a friendly passerby when you need one, or turn you into a
ministering angel when you see someone else with a flat battery. You can
also do nifty diagnostics with them.

Batteries store electric charge supplied by the alternator. The electrons
get pushed out one end of the alternator, travel through a wire, do some
chemistry inside the battery, and go back into the alternator through
another wire to repeat their cycle. Often the car's metal bits are used as
part of the circuit. A flat battery indicates a fault that could be anywhere
in that system -- battery, alternator, wires, or the connections between
them.

You can check most of your circuit with your jumper cable. Not an ideal way
of doing it, but better than nothing. Start the car and leave it idling. If
all is well, it should be charging the battery. Turn your headlights on low
beam. Even at idling, the alternator should be able to keep up with the
demand. If the headlights start to dim, you know there's a problem
somewhere. Let's start with the fat cable that connects between alternator
and positive battery terminal. Hold one of the jumper clamps onto the top of
the battery post (it's only 12-14 volts and won't bite you) at the same time
holding the other end away from the car. (If you touch the cable to any
metallic part of the car while it's connected to the battery, you'll get
quite spectacular sparks and may even damage your battery.) We're using only
one lead for this test, either the red or the black. At the back of the
alternator there's a short threaded rod and a nut that attaches the cable
that goes to the positive battery terminal. There should be a plastic
protector over this which you can push off with a screwdriver or nail file.
Now make good contact between the jumper clamp and the alternator connector,
at the same time pushing the other clamp firmly onto the positive battery
post. Watch your headlights. If they brighten, you've identified a problem
area.

Do the same thing between the negative battery post and any solid piece of
metal that bolts to the engine. Again, brightening lights indicate that
you've identified a problem area.

If the battery wires are the problem, start by turning off the engine. Try
to twist the connectors off the battery posts with your fingers. You
shouldn't be able to. If you can, clean the post with a metal brush,
metallic pot scrubber or sandpaper, and clean the inside of the connector in
whatever way you can. A small sharp knife works well. Slacken off the nut
that tightens the connector and push the connector hard onto the post. Then
tighten the nut. (You do have a set of wrenches, don't you?) Don't hammer
the battery post; the inside of a lead-acid battery is somewhat fragile, and
gets more so with age.

Tighten the connections at the back of the alternator and at the end of the
wire or woven strap that goes between the battery negative post and the
engine or chassis. Also make sure that the wires are held firmly in the
battery terminal connectors and haven't corroded away under the insulation
near the connector (you'll see it quite clearly if they have).

Purists put silicone jelly inside battery and alternator connections. It
tends to prevent corrosion. However, right now, we're more interested in
getting you going.

Start the engine and see what success you've had so far. If all's well, you
should be good for many more miles. If not, and you've eliminated the
connections and cables as culprits, we need to check the alternator. Three
questions:

1.  Does the battery light on your instrument cluster light up when you turn
on the ignition? This light is critical; the current flowing through it
creates a small electromagnetic field inside the alternator which enables it
to start producing current -- kind of a bootstrap operation. No light, no
current. And if there's no light, you'll need to get it fixed.

2.  Before the problems started, did you notice an increase in static in
your radio, perhaps accompanied by crackle when you went over a bump? That's
the sound the alternator brushes make when they're worn to the point where
they're barely making contact, and a sure sign that replacement is just
around the corner. If someone you know is handy with a soldering iron -- and
has done this kind of job before -- s/he can replace the brushes without
replacing the regulator board on which they're mounted. That'll save you $40
or thereabouts. The regulator itself is pretty hefty and rarely gives
trouble.

3.  With the engine running and the hood up, can you hear the alternator
from more than a few feet away? (Think, grinding howl.) If so, that probably
means new bearings or, more practically, a rebuilt alternator for around
$150.

If you can lay your hand on a multimeter (dirt cheap and perfectly
serviceable from places like Harbor Freight) you should check the output
voltage from the alternator across the battery terminals. 14V is  the target
but it needn't be spot-on. A multimeter also lets you check for voltage drop
across connections -- a much better method than using jumper cables but
beyond the scope of these get-you-home diagnostics.

Finally, before blaming your battery, do a quick check for abnormal current
drain -- shorted wires, courtesy lights left in the On position, that sort
of thing. A fairly reliable check is simply to switch everything off,
disconnect the negative battery lead and check for voltage/current between
it and the battery. A multimeter is the ideal tool, but you can also use a
small flashlight bulb. The only flow should be through a radio alarm circuit
or some such other device that is constantly on.

Good luck!

Pete (fP)