I think i have a battery drain. any common places to start?

[flyingfool]

I had to get a new battery and when i put the new one in, car fired right up, no issues. took it around the block a few times just for kicks, and then parked it. went to go start it up 2 days later, and now dash lights and such barely come on and i get no action.

(lights and such are off.)

[baller908790]

Is your alternator working?

[Hans]

there's not much potential for parasitic drain on a 2002. Perhaps a radio on un-switched circuit? As suggested, I'd look at charging system first. With engine running, you should see 14v at battery. Loose belt would likely create cooing issues. Some have reported drain thru alternator fault. For instructions for testing for drain, search on Bimmerforums E46 page - I saw it there recently.

[xferboy]

if it's in the budget, get a current clamp meter that does DC* (or find a friend that has one). Charge the battery, (play with the meter on the charger to learn how it works, remove when charged) Clamp around one of the battery leads (doesn't really matter which). If there is current flowing, start yarding out fuses to eliminate circuits, zeroing in on the culprit.

*Not all clamp meters do DC, confirm in the specs. Alternately, there are addon clamp meters if you already have a good meter.

[ray_]

Check your cable connections too.

GL,

[allbim]

After you charge the battery, take any multimeter and put it in a range that will let you measure .5 amps DC.

With everything turned off, pull one fuse at a time and connect the amp meter to the fuse terminals. The positive lead goes to the hot terminal.

If you read anything, you found a leaky circuit. Be careful, if the meter is connected to 12 V and the other lead is even momentarily grounded (while your'e in the current measuring mode), you will most likely destroy the meter.

It is also possible that the battery is draining through some bad diodes in the alternator. As was mentioned before, a clamp-on DC amp meter is the most convenient way of checking that, but a regular meter will work too.

[bnam]

i'd start with removing the negative cable from battery and connecting multimeter in Amps mode between the negative post and the end of the negative cable. If there's current, you've got parasitic draw. Then go to the fuses to determine which circuit/s are to blame.

[OriginalOwner]

here's a recent thread on the topic ..... lots of info .....

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,381025

Cheers,

Carl

[c.d.iesel]

f.fool ,

alternator history ?________________

how old is alt. ?___________________

describe condition of wires to alternator and batt. ? ________

is there a clean solid GROUND cable from Batt to BODY ?____

is there a GROUND from Engine Block to Body ?_____

is there a GROUND from Alternator to Eng Timing Cover ?_____

was alternator replaced since you owned the car ?____

source for the replacement ?_________________

have you had charging issues ?_______________

do you know Volts @ Batt. key off ? ________V

do you know Volts @ Batt. @ idle speed ? ____V

do you know Volts @ Batt. @ 3,500 RPM ? ____V

do you see any instrument lights glowing

with motor running ? _____

how long have you owned car ? years?__ miles?__

is there a radio/big audio installed ?__________

is there a bundle of wild wiring anywhere on the car ? _____

do wipers, all lights, heater fan work correctly ?______

[xferboy]

Keep in mind that most meters that you put in series with the circuit to measure current have a 10A max rating. If you exceed that it will burn a fuse in the meter.

[flyingfool]

f.fool ,

alternator history ?________________newer looking since i got it. clean compared to rest of engine

how old is alt. ?___________________unknown

describe condition of wires to alternator and batt. ? ________bit greasy but have cleaned then with bit of steel wool

is there a clean solid GROUND cable from Batt to BODY ?____will check on that

is there a GROUND from Engine Block to Body ?_____ground from baided cable from block to battery. could be replaced

is there a GROUND from Alternator to Eng Timing Cover ?_____have to check

was alternator replaced since you owned the car ?____no

source for the replacement ?_________________

have you had charging issues ?________ never had any issues.

do you know Volts @ Batt. key off ? ________V 6

do you know Volts @ Batt. @ idle speed ? ____V will check tommorow

do you know Volts @ Batt. @ 3,500 RPM ? ____V

do you see any instrument lights glowing

with motor running ? _____ no

how long have you owned car ? years? 3 miles?__

is there a radio/big audio installed ?__________yes. does not work

is there a bundle of wild wiring anywhere on the car ? _____nothing that looks to out of the ordinary

do wipers, all lights, heater fan work correctly ?______

yes, except dash lights. they have been intermitant. fuse usually

[flyingfool]

checked out alternator and grounds. cleaned grounds, alternator is running at 13V when engine running.

if its a diode, would that effect the performance of the alternator while its running or is that simply a connected circuit that could cause a drain?

[allbim]

Before you do anything else, check if you have any drain on the battery when everything is turned off. If you do have some current (more than 20MA) pull one fuse at a time and watch the meter.

If pulling the fuses makes no difference, disconnect the alternator. Do that and report back please. Measuring is better than guessing.

[dansacto13]

Hello there. I'm following this thread very closely. My 74, which I just bought, seems to be having battery problems. Just like the opening remarks I put a brand new battery and 2 hrs later the car will 'barely' start. In my case battery is at 13V, checked alternator fine, and most important....no higher voltage when metering from negative battery end to terminal. It sucks because now I have to eliminate 'parasitic draw' which is relatively easy to locate.

Good luck with your search.

Dan in Sacramento,CA

[Tmta]

I am having a similar problem.  I replaced the alternator a few weeks ago and replaced the battery today.  What does the "L" warning light indicate?  I was told it meant a low battery.  That light still comes on with the new fully charged battery.

 

Tom