Help with battery drain

J

Jayant

Just bought a 2000 Forester L with automatic transmission. The car
has 67,000 miles on it but was well maintained and runs good. However,
I have my first challenge. The car cranks very slowly first thing in
the morning. I load tested the old battery and it tested weak so I replaced
the battery. The other day my wife tried to start the car and it did not
start (cold mornign about 3degrees F). I measured the battery voltage
and got only 9.95 volts. After putting the charger on it the car started
fine and the alternator voltage was 14.45 volts at idle. Looks like
the alternator and the regulator are fine. After running the car for
about 15 minutes the battery voltage came up to 12.65V.

Something is draining the battery. The only thing that could be active
when the car is off and the security system is armed is the security
system. Can someone help me with diagnosing the problem? Is there a
fuse (or fuses) I can remove and measure the current drain? What should
it be? Any help will be appreciated. I apologize if this has been
discussed before.

TIA,
Jay
 
Have you tried not setting the alarm, or is that not an option in your area?
Are all the dome lights off? Check the obvious first.
 
Jayant said:
Just bought a 2000 Forester L with automatic transmission. The car
has 67,000 miles on it but was well maintained and runs good. However,
I have my first challenge. The car cranks very slowly first thing in
the morning. I load tested the old battery and it tested weak so I replaced
the battery. The other day my wife tried to start the car and it did not
start (cold mornign about 3degrees F). I measured the battery voltage
and got only 9.95 volts. After putting the charger on it the car started
fine and the alternator voltage was 14.45 volts at idle. Looks like
the alternator and the regulator are fine. After running the car for
about 15 minutes the battery voltage came up to 12.65V.

Something is draining the battery. The only thing that could be active
when the car is off and the security system is armed is the security
system. Can someone help me with diagnosing the problem? Is there a
fuse (or fuses) I can remove and measure the current drain? What should
it be? Any help will be appreciated. I apologize if this has been
discussed before.

TIA,
Jay

Jay,

A useful technique is to connect an ammeter with a range giving a
full-scale reading of about 10 amps (such as a suitable VOM meter) in
series between the battery and the battery cable and then observing the
meter as various circuits are disabled by disconnecting fuses, etc.

The important point to understand is that various circuits, such as the
computer and alarm will draw some current with the car turned OFF so the
question is whether there is excessive current draw. Additionally, some
circuits may initially draw a higher current and then drop back to a
continuing, but acceptable, parasitic level. On a 10 amp scale, normal
parasitic current draws will not visiably move the needle but problem
draws will be immediately apparent.

Attempts to measure "draw" with a volt meter or a test light from
battery terminal to disconnected battery cable likely will not be
meaningful.

Ed P
 
Greg,
I did all of these things first. Not setting alarm is a good point and I did
try it but no difference.
The car was parked for a week at the airport and it cranked slowly but started
up OK. Then when I drove it home it got worse!

Thanks for responding. I will plod along and try to find the source of drain.
Jay
 
Ed,
I am aware of the things you point out. I am an electronic engineer. Not having
service manual or a schematic is a big brawback.

What I was looking for is someone to point out that fuse number so and so feeds
the keyless entry and fuse so and so feeds the security system. It would narow
down the troubleshooting to a limited number of devices. You do not have wiring
diagram do you?

I will plod along and pull each fuse and relay and see If I can find the
cuprit. I do not even know where the security module is mounted. I would
appreciate if you can provide additional help.

Thanks for responding,
Jay
 
It may not have any bearing on your situation, or perhaps it
will spur an idea:

I once had similar symptoms on a '86 Old
The retractable antenna had stopped
retracting which I knew, and THOUGHT was o.k. Only after
fighting the weak/dead battery symptom for weeks, one day I
happened to be sitting in my car after I turned the key
off to hear an faint, intermittent click, which turned out to
be the motor continuing to try and retract the antenna.
Removing the relay solved that problem.

Jim
 
Jayant said:
Ed,
I am aware of the things you point out. I am an electronic engineer. Not having
service manual or a schematic is a big brawback.

What I was looking for is someone to point out that fuse number so and so feeds
the keyless entry and fuse so and so feeds the security system. It would narow
down the troubleshooting to a limited number of devices. You do not have wiring
diagram do you?

I will plod along and pull each fuse and relay and see If I can find the
cuprit. I do not even know where the security module is mounted. I would
appreciate if you can provide additional help.

Thanks for responding,
Jay

Jay,

On my 96 Outback the keyless remote controller is is suspended by two
plastic tiewraps under the dash on the extreme left side and near the
firewall. There is a button hanging from the wiring harness an inch or
two from the controller.

Ed P
 
Do you have an aftermarket radio? Sometimes those are not installed
correctly and cause battery drain. In any case, try pulling the radio fuse
and see if that helps the problem. I doubt the alarm has anything to do
with it.
 
No, everything on the car is Subaru and was instslled by the dealer.

Intresting thing is that since I started 'poking around' it has not done it!
may be something was stuck 'on' or some wire pinched somewhere. I hate it when
things fix themselves.
 
I have the same problem with my 2000 Outback limited. I just took it into
Sears to get a new battery because the car was starting slowly on cold
mornings and a parking lot notified me that my car had a dead batttery when
they tried to start it on my return. Sears did a number of tests on the
battery and alternator and said it was fine but that I had a drain on the
battery when the car was off.

I haven't a clue where to begin to troubleshoot this drain. The only
coincidential item is that I changed car chargers for a cell phone about the
time the problem started cropping up, but since the lighter is off when the
car is off, that doesn't make any sense, though I have pulled the plug on
the charger just to see if it makes a difference. I also had a problem over
a year ago with the moon roof motor activating itself one rainy afternoon
when I was driving along.

Any suggestions on how to troubleshoot this problem?
 
JDC,

I am going to keep after this problem until I find the problem. I will post the
details of the fix when I find it.
The basic process is to put and ammeter in series with the battery and pull
fuses one by one and if one of them removes the drain you have found a circuit
that is causing the drain. Then if there are more than one devices on that
fuse, you either disconnect them one by one or trace a short in the wiring. It
is a tedious job but that's the way you do it.
There might be devices that have this tendency to short but I do not know of
any. I just got the car a few short weeks ago.

HTH,
Jay
 
We had battery drain on a 93 impreza, a healthy4 or so amps. heard clicking
when connecting the battery terminal and traced it to the rear door lock
solenoid. Our solution was to pull the fuse for the door locks.
Dave.
 

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