I have a 92 Honda civic ex the car runs fantastic but in the last
couple of days my battery has been draining. I disconnect the battery
and the car dyed I heard that this means that it is the alternator
could it be?
Also I find that I am burning my headlights out fast. They are
sealed, there is no moisture or cracks they are single bulbs. It
seems that I am burning running & high beams alot, like every 2nd 3rd
month I am changing them. Any advice on this would be appreciated.
Thank you in advance.
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Check battery and alternator as described at
How old are the battery and alternator?
Have you ever had the red warning lamp with the battery icon
(= actually the charging system warning lamp, typically
indicating a faulty alternator) come on?
1- Never disconnect the battery on a vehicle with the engine running.
2- You may have neglected to squeeze the tiny triangles on the headlight
connectors, then yanked the connector off. You'll have to repair the
'grip' that the brass lugs are supposed to exert on the lamp's prongs.
Since they have overheated now, replacement of the whole connector is
probably required. When the connectors get hot they contribute to the
lamp burning out since they stop conducting heat (away from the lamp)
and start generating it.
3- If overvoltage was the cause of your headlamps burning out, your
radio would be toast too.
4- Test your dash warning lights per the owner's manual to be sure all
Elle is on the right track here; Curly is on glue.
Definitely sounds like an alternator issue. Your first test of disconnecting
the battery was the right one; you don't want to run that way for very long, but
it's still a valid way to isolate battery from alt problems.
Your best bet is probably to go to a shop that can properly test and repair (if
necessary) your alternator, but if you want to diagnose it yourself, the first
thing you're going to need is a multimeter, preferably digital. Most auto-parts
stores should have basic ones starting at around $15-$20. With that, you can
perform some of the tests in this document:
http://assets.fluke.com/appnotes/automotive/beatbook.pdf (note that they show
Fluke meters, since this is Fluke's document, but any meter with the same
functions will do the job).
Check for overvoltage first - connect the meter across the battery posts and rev
the engine; watch that it doesn't go above 15 volts DC. Turn all the
accessories on (rear defrost, lights, fan, etc.) and watch the voltage. In
normal conditions, it should be around 13V at idle with everything off, down to
12-12.5 with accessories on, and around 14.5V when revved up.
If it is in fact overvoltage that's killing your lights (and despite Curly's
assertion, a slight overvoltage can easily shorten the lifespan of your
headlights without killing the radio), it's possible that it's also damaged your
battery, and that's not holding a full charge anymore. If you find the reading
too high, have your battery tested as well (any auto shop should do this for
I agree with Curly; the risks of disconnecting the battery with the engine
running are terrible. With a good alternator it is a little risky, with one
that has bad diodes (you do suspect the alternator is bad, right - why else
do the test?) you seriously risk huge spikes to all the electronics in the
car. It's not a big deal with a car made before about 1970, but don't *ever*
do it with a modern car. It never was a very good test, either; alternators
with bad diodes would still run the car but would fail to keep up with loads
like driving at night with the heater fan on.
The way to determine whether the alternator is working is with tests as Elle
describes. Personally, I also check for AC voltage with a digital voltmeter
under the same test conditions. Good diodes will produce less than 0.1 volt
AC, while bad diodes will produce 1/2 volt AC or more. The last bad
alternator I've seen (in a friend's Taurus) had two bad phases and the AC
voltage was 1.7 volts! An oscilloscope is even more definitive, as the
waveform of a bad phase is unmistakable, but in practice I've never seen
high AC voltage from an alternator that didn't have bad diodes. Alternators
with bad diodes will also fail Elle's test #3.
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