Tracking a drain
Discussion
So it has become apparent that I have a drain on my E30
The alternator has been tested and said to be ok and a new battery installed, the car is fine if I drive it leave it for a day, no probs
Leave it for a week and a flat battery
So the FiL is coming over tomorrow with a multimeter to try and help track down where the battery is being drained
I understand the theory of hooking the meter up and removing fuses until we get the requires result
The main question is what result are we looking for?
What readings should I be getting with the car off and no draw and then what change should we be looking for when we (hopefully) find the offending item?
The alternator has been tested and said to be ok and a new battery installed, the car is fine if I drive it leave it for a day, no probs
Leave it for a week and a flat battery
So the FiL is coming over tomorrow with a multimeter to try and help track down where the battery is being drained
I understand the theory of hooking the meter up and removing fuses until we get the requires result
The main question is what result are we looking for?
What readings should I be getting with the car off and no draw and then what change should we be looking for when we (hopefully) find the offending item?
You say alternator has been tested and found OK. In what way was it tested?
Wife's Golf is rarely used and battery was running down quickly. Was advised to disconnect the alternator and see if the battery then went flat, which it did not.
The alternator charges fine but the battery seems to discharge itself through the alternator so needs changing or regulator (diode?) needs replacing.
Worth checking this but problem is it will take you a week to find out.
HTH
Wife's Golf is rarely used and battery was running down quickly. Was advised to disconnect the alternator and see if the battery then went flat, which it did not.
The alternator charges fine but the battery seems to discharge itself through the alternator so needs changing or regulator (diode?) needs replacing.
Worth checking this but problem is it will take you a week to find out.
HTH
If the alt was tested properly then the diodes would be ok because it would show ac on the output.
50 milliamps is/was the rule. (Drain current)
BUT cars are so frigging complicated now. before it was just the clock, radio and one module.
Now it's a dozen modules and shut down times.
Test the car cold (next morning) and shut down times do not matter.
Leave some bits of paper in the fins of the rad cooling fans to make sure they are not coming on from a bad sensor.
Check door controlled lights are off. Sounds silly, but it happens.
Charge batt the day before testing, you should get 12.5+v. (the next day)
Load test batt, just because it's new doesn't mean a thing. batteries are uasually good for either three years or ten minutes
OH remember to close the doors when testing
Do a check that there are no detrimental effects when disconnecting battery, some cars need a 12v feed into the cig lighter esp if you are getting a smog test in the next couple of days. It will fail if codes are reset. It will re-learn though.
A lot of un-necc info there, sorry.
50 milli amps is the ansewer you need.
50 milliamps is/was the rule. (Drain current)
BUT cars are so frigging complicated now. before it was just the clock, radio and one module.
Now it's a dozen modules and shut down times.
Test the car cold (next morning) and shut down times do not matter.
Leave some bits of paper in the fins of the rad cooling fans to make sure they are not coming on from a bad sensor.
Check door controlled lights are off. Sounds silly, but it happens.
Charge batt the day before testing, you should get 12.5+v. (the next day)
Load test batt, just because it's new doesn't mean a thing. batteries are uasually good for either three years or ten minutes
OH remember to close the doors when testing
Do a check that there are no detrimental effects when disconnecting battery, some cars need a 12v feed into the cig lighter esp if you are getting a smog test in the next couple of days. It will fail if codes are reset. It will re-learn though.
A lot of un-necc info there, sorry.
50 milli amps is the ansewer you need.
May be telling granny to suck eggs but.
If the car has and airbag system be very careful poking around
it or its power feeds or you may have an amusing/expensive/painful
indecent.
ETA. if the car has a modern factory immobiliser of the type
that syncs with the key beware of leaving the battery disconneced
for too long of you will have a dead car and need the unlock code
and method of entering it which is a right PITA.
If the car has and airbag system be very careful poking around
it or its power feeds or you may have an amusing/expensive/painful
indecent.
ETA. if the car has a modern factory immobiliser of the type
that syncs with the key beware of leaving the battery disconneced
for too long of you will have a dead car and need the unlock code
and method of entering it which is a right PITA.
Edited by FranKinFezza on Saturday 22 January 14:39
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