I have a 88 Ford Tempo that I've recently been having a problem with. In
the morning when I go to start it the battery has drained out overnight. I
can jump start the car and it starts up and drives just fine. Drive it
around for awhile and the battery seems to charge back up. I can start the
car numerous times throughout the rest of the day.
However, when I come back out in the morning the battery is dead. I put in
a new battery two months ago so it's still new. I've checked to make sure
nothing is being left on overnight. Does anyone have any ideas what could
be draining the battery out overnight? How do I go about fixing this?
Thanks for any thoughts...
Glove box or trunk light switch, maybe. Try unhooking the battery
overnight to see if it holds a charge that way; if not, replace battery.
If battery's OK, rent/borrow a clamp-on ammeter and clamp it over the
positive battery cable & observe current draw (s/b in milliamps with
engine & lights off; if more than that, probable alternator diode or
VR). Start pulling fuses, observing ammeter after each pull. That will
locate the circuit that's causing the draw.
Alternative, a test light made up of an interior bulb, installed between pos
term and its cable. If it glows, drain is active - the brighter, the higher
the current drain.
Disc alternator first, then check doors/trunk glove box, then fuses
- Yes, I'm a crusty old geezer curmudgeon.. deal with it! -
the car is at rest. Have the battery charged and tested. If ok, then check for
draw with an ammeter at the battery "POS" terminal. Make sure the doors are
all accessories are off. Connect an ammeter between the post and the cable. The
should be .05 amps or less. If more, remove all of the dome, courtesy, hood,
and glovebox light bulbs. Recheck your current draw. If one of these lights is
on it will drain the battery, although usually not overnight.
Also, disconnect any aftermarket lamps, radios,amplifiers, or other add on
accessories and recheck.
A very likely culprit is the voltage regulator on the alternator. They often
internally and cause a drew when the engine is not running. An easy check for
to unplug the connector on the side of the alternator when you park the car for
night. If the battery is ok in the morning, the regulator is shorted.
Might have a 'parasitic' loss somewhere. It's easy enough to check...
Remove the negative battery cable, and install a 12V incandescent test
light in series between the Neg battery post and removed cable.
Be sure the key and everything is off, and doors closed. The test light
should be off.
Should it be on, remove fuses one at a time till it goes off... the
problem is powered by that fuse. Don't forget about keeping the door/s
closed during the test/s or the dome light will give you a false
Glove compartment and trunk lights that stay on are prime candidates.
You could have a bum battery too... new doesn't mean good.
You have to be careful doing it this way. There will always be parasitic draw
the PCM, Radio, Clock, etc. memory circuits. Many test lights will light
in series with even this low current. That's why an ammeter should be used.
I'd agree with all the above - check for a draw, but don't be
surprised if you don't find one.
Better to find a shop with a Midtronics battery tester and have the
battery tested. I've never seen a Midtronics fail a good battery - and
only ONCE saw it pass a bad one.
I tested what I was sure was a bad battery (same symptoms as OP) and
it showed bad - but little brother, being the dealer, needed to
verify. He tested it and it passed - so I put it back into the
miserable Pontiac TransSport - and it failed to start the next
morning. I dragged little brother's ass out into the cold to test it
again, and lo and behold, it failed. Changed it under warranty, and
the problem has not returned.
Battery Probably has a dead cell and needs replacing or you have a problem
w/ the alternator, voltage regulator. test the electrolyte in the battery's
cells first. add distilled water to cells if needed. if the electrolyte is
no good replace the battery. if it is still being drained test the
alternator and voltage regulator and replace if necessary. Also check the
belts for slipping. if that doesn't work then you have an open short
somewhere in the wiring that is draining the system--Good luck!
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