Battery keeps discharging, help needed diagnosing problem

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PunjabiMc (PunjabiMc) 2012-01-13 11:13:07 +0500 #1

Salam all.
My car is having a problem right now where it's battery keeps discharging.
After i bought it, i had an aftermarket security system installed the next day. After a day or two, the battery became very weak and i had to start the car using jumper cables multiple times.
Then i was away for a week and on my return took it to the mechanic(for some other work too). The electrician opened the starter and replaced the armature. He told me some cables were crossed which was causing the battery to continuously discharge when the car was off.
The electrician charged the battery and i brought it back. The car worked perfectly fine for a day, it was starting perfectly. The following day i went to get my RPM meter connected (as it had been disconnected somehow) in the morning. Then i had to make multiple short trips in the evening to and from from my house. After a while when i started the car again it took some extra 'salf'. And then again, and again. Finally i got home, parked the car. In the morning the battery was completely dead again.

What could the problem be? Faulty wiring? Alternator issue? Alarm system? I will take it again tomorrow but wanted to have other opinions too.

dr3vil (Maalik ) 2012-01-13 12:33:16 +0500 #2

which car it is?

takko (takko) 2012-01-13 12:37:57 +0500 #3

something wrong with the wiring.. see if u have left any untaped wiring,

ToxicDevil (ToxicDevil) 2012-01-13 13:06:46 +0500 #4

Is the battery new? wet or dry?

capsat (ومن شر حاسد إذا حسد) 2012-01-13 13:28:31 +0500 #5

the after market system is draining the battery. test it by disconnecting the system straight 24 hours.

Xulfiqar (Xulfiqar) 2012-01-13 15:58:18 +0500 #6

remove the battery negative terminal and connect your digital multimeter between the battery and the negative cable, set your DVOM to measure amps.

use a 7.5 or 8 amp inline fuse to protect the DVOM, check the amps with everything off, it should be a very small amount if your car is EFI and has a radio too. something about 10 to 20 milliamps. If you see 1 amp or more you have a problem, if the fuse blows you have a draw of more than the fuse you used.

Start by disabling certain circuits like the aftermarket security system, you will find your problem as soon as the draw drops by removing the culprit.

PunjabiMc (PunjabiMc) 2012-01-17 11:26:01 +0500 #7

Just an update:
It rained heavily in Islamabad over the weekend so i was unable to take the car to the mechanic. Today the electrician opened the starter and showed that the new armature's 'tankay' were open. Also he replaced the grease type.
Thank you all for posting. Inshallah the issue is solved now

capsat (ومن شر حاسد إذا حسد) 2012-01-17 11:57:25 +0500 #8

armature 'tankay' you mean soldering on armature winding was borken? now thats something I will wait for GURU XULFIQAR to explain.

Xulfiqar (Xulfiqar) 2012-01-17 20:08:55 +0500 #9

the only solders in the armature are on the commutator, and even then it does not have anything to do with battery discharge overnight.

The starter windings are only energised when the solenoid is pulled in and the contacts bridged. Sounds like the electrician took a "wallet" for a ride.

PunjabiMc (PunjabiMc) 2012-01-21 15:35:31 +0500 #10

The electrician was referring to the round bit at the end of the armature. If i had a picture i would point it out. The previous guy who had replaced the armature must have left it like that on purpose (i had taken the jeep for some major engine work and told the electrician there to check the starter). Alhamdolillah its been a few days now and the problem is solved.

Xulfiqar (Xulfiqar) 2012-01-21 18:23:31 +0500 #11

Yes I know and as I said its called the commutator - its the part where the carbon brushes ride on. If some solders were open the starter would have dead points on it, meaning that if under some circumstances the starter came to rest with a carbon brush on that contact the starter will completely refuse to spin. It has nothing to do with the battery getting drained as it only gets power when the main heavy starter solenoid gets pulled in, and btw a starter motor draws 300 to 400 amperes, a short in such a motor will instantly kill a battery no matter if it was made by Rolls Battery.

It seems that you were mislead to a dead battery diagnosis, because when a commutator pole is open the starter speed slows down condsiderably or as I said if the starter stops that a carbon brush is contacting that open pole it will be dead, not even the solenoid would pull in because the ground to the solenoid goes through the commutator too.