battery drain help???

Sun Dec 27, 2009 6:16 pm

battery keeps dieing on me every other day. its my 3rd battery from hellfrauds.

when i charged it engine was off i connected voltmeter to it and measured the current and it kept decreasing from 12.30 to 11.89 and so on every 20secs or so i even turned the boot light off and took out my fuse for the headunit and yet the current kept decreasing. the only thing that is on is my immobiliser but that just blinks and hardly takes out any current.

ive been experiencing this problem ever since i repaired my obc which was the bulbs had blown soldered new bulbs 5v each works fine now.

however when the engines running i measured the current again and it said 13.40 but then the current kept decreasing again every few seconds which is weird.

its my 3rd battery brand new battery ive had it since 3 months ago and surely it cant be the battery again ????

tomorrow i will disconnect the obc and see if the current is still draining ...if the current still presists what can it be the alternator ???

thanks.

Sun Dec 27, 2009 6:59 pm

It's the voltage of the battery, not the current you want to be testing.

Connect the battery up and start the car up. See how many volts there are across the battery terminals while the car is running. It should go up to about 14 volts, maybe with a little light rev of the engine.

If you're not getting charging from the alternator check that the earth strap between engine and bodywork is in good condition.

When you turn the ignition on do all the lower lights on the dash come on (oil pressure light, alternator charging light etc)?

Sun Dec 27, 2009 7:49 pm

sorry i meant to say voltage.

where is the earth strap located and how does it look like ??? i have a 325i facelift.

when i turn the ignition on yes all 6 lights come on the dash board.

i gave it some rev and it didnt go up to 14v. it stayed from 13.60 and kept decreasing 13.58 every few seconds while the engine was on.

any thoughts on that ?

thanks.

Sun Dec 27, 2009 10:00 pm

does the battery light in the cluster stay on or flicker while driving? that little batt. light isn't an idiot light and is essential to the user, with respect to the charging system. Based on what your symptoms are, I would seriously check that your alternator belt is tight (yes simple, but easy and moving saving check nevertheless), then check and clean the all of the grounds on the chassis. If you need a diagram pm me. If after you've done all that and tightened the battery down, then I would pull the alternator and check/clean the brushes and/or change bushings.

This is labor intensive but, it'll save you dough, you'll learn along the way, and most importantly you're diagnosing things properly! ;) Good Luck!

Mon Dec 28, 2009 10:26 am

hi k13
sounds like it could be an alternator( no expert just been through this on my car!!)
the alternator brushes were easy to change on my 316 just unscrew the voltage regulator unit and pop in new one 5 min job. not sure on your model?

an easy way to check stationary current drain is to put the multi meter in dc amp mode and undo the live batt terminal connect one m. meter lead to the terminal and the other to the live clamp. then read the amp drain then remove each fuse until the amp drain stops then you have the circiut which is using the power.
hope that is of some help carl.

Mon Dec 28, 2009 1:47 pm

DO NOT REMOVE AND CONNECT THE METER IN THE LIVE LEAD!! Connect it in the negative (earth) lead.

Mon Dec 28, 2009 8:35 pm

why not the live lead!?? not doubting you just wondered why( and what damage i may have done in the past!!)

carl

Mon Dec 28, 2009 9:31 pm

The damage that you will do is either when the back end of the spanner you remove the clamp with touches the bodywork, or when the red meter lead does the same. Never do anything with the live battery terminal while the earth lead is still connected.
Ever seen a 13mm spanner glow red hot?

Mon Dec 28, 2009 9:55 pm

carl21 wrote:hi k13
sounds like it could be an alternator( no expert just been through this on my car!!)
the alternator brushes were easy to change on my 316 just unscrew the voltage regulator unit and pop in new one 5 min job. not sure on your model?

an easy way to check stationary current drain is to put the multi meter in dc amp mode and undo the live batt terminal connect one m. meter lead to the terminal and the other to the live clamp. then read the amp drain then remove each fuse until the amp drain stops then you have the circiut which is using the power.
hope that is of some help carl.

Couldnt of said it better myself. Glovebox light staying on? Iv had this a few times before. The ampmeter will read a drain of about 0.2 to 0.8ma this is normal probably your clock