1 year old battery not charging!
 

Hi,
My 2003 X5 3.0i a week ago started displaying red battery light intermittently. Few days later car did not start and I had to use my jump starter. I have been driving the car a few times and every time that I need to start it, I use the jump starter. The car is fine as long as I don't turn it off.

Is the issue with Battery or Alternator? I had removed alternator 2 months ago to change washer on oil filter housing. The battery is less than a year old and was an expensive one. It did not charge when I had the jump starter connected to car over night.

I am thinking to drive it to Advanced Auto Parts and ask for test and exchange/refund if needed.

Is there an easy test to rule out Alternator?

The light wont tell you if you have a bad battery. It is telling you the alternator isn't charging.

You can unlock the cluster and go to test 9 to see if alternator is working as it should. Voltage should show around 13.8 with engine running. Or, you can connect a multimeter to the battery or on the jump start connectors under the hood and read charge in battery and alternator output when engine is running. If you want to check the battery I suggest having the battery load tested. Most places that sell batteries will do the test at no charge.

Check to see if you have an oil leak that is getting into the alternator. I had a problem with my 645Ci/N62 motor. Oil was leaking from the rocker covers and getting into the alternator. This was throwing up Low Battery warnings. Also I got a replacement regulator and fitted that. All good now. Nothing wrong with the battery.

Oil got in my alternator and it killed the output. Voltage should never drop below 13.4 even at idle. I replaced my slip rings and brushes for $20. How many miles ?


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On wifes e46 this was an indication the voltage regulator was gone on the alternator and it didn't help there were party ribbons! somehow lodged into the windings of the alternator.....as the other chaps have said you need to be looking for 13.8-13.9v whilst engine running once you unlock the OBC....personally I find the OBC volts reading a little higher than when I used the digital multimeter at the jump points to read voltage.

PS from experience a good voltage not really a sign either that battery good, found this out the hard way the other day was getting 12.6 on a battery, but it would subsequently not hold charge

Owners manual says that the battery warning light illuminates when the battery is the VICTIM and is not being charged by the alternator/charging system.


Ditto the suggestion above...you can unlock your OBC/instrument cluster and do TEST 9. In TEST 9...if the engine is RUNNING...then you are looking at the alternator/charging system's voltage. If the ignition is in position 1 or position 2 (engine NOT running)...then you are observing the battery's voltage.

To check the battery...always check it PRIOR to starting the engine or approx 2 hours after shutting the engine off. This will allow any surface charge from the car's alternator/charging system to dissipate.

The test for the alternator is free at an auto parts store; (but you need to remove it). You can test the running voltage with the hidden test 9 on the dash. if it dips below 13V ever it's having problems. If you had an oil leak that got into the alternator and it's original or over 100k miles I would bet that is the problem. If it's not terribly old you can refurb yourself pretty easily; the regulator comes off pretty easy and not terribly difficult to re-install (just a bit tricky to push in the brushes to get over the slip rings). You can clean the slip rings and de-grease the brushes/regulator etc. If the slip rings aren't terribly worn and it's just a matter of too much oil, simply cleaning them will get you back to perfectly functional.

The slip rings only carry enough current to power the magnetic field, they couldn't push 1/ 20th the current of the actual output, there is a special burnishing tool for properly cleaning slip rings you can find it searching 'contact burnishing tool' but fine sand paper will work, you just don't want to create grooves that the brushes need to smooth off it will take 1000s of miles off the lifespan.

If you slip rings are shot and/or the brushes are shot, you can buy a kit for $20 that includes both. It took me maybe 90 minutes to disassemble, clean in my kitchen sink using dish soap in a spray bottle and rinsing, re-build the slip rings and re-assemble. Heat was my friend to remove the old slip rings to release the potted connections. The YouTube video i followed chiseled it out but with some heat from a micro torch it released the whole potted chunk in one piece.

The regulator can be bought as a kit as well and will have new brushes included, saving some work and if the slip rings are ok but brushes are worn that will likely fix your problem.

First get the voltage measurements while running; if they fluctuate a lot and especially can't stay above 13v it's the alternator that's the problem. Make sure your output nut is tight; i forgot to tighten mine on re-assembly and it fell off giving me all sorts of fits including transmission safe mode.

If the voltage dips below about 12v while running you should see secondary failures like DSC/brake (yellow) failure.

A properly operating alternator won't vary more than about 0.4v ever. 13.4 to 13.8 volts for example. from idle to redline and it shouldn't take long to stabilize either. if the voltage wanders or dips/spikes the regulator is not doing its job. The primary reason will be dirty/worn brush/slipring but some other parts can fail in the regulator which likely can be determined with the actual bench test (e.g. regulator or stator the cause).

FYI; many don't realize but the way that alternators can output constant voltage independent of RPM is that they take some of the output power, feed that back into the armature through the slip rings; the regulator monitors the output voltage and changes the current instantaneously going into the armature to boost or lower the output. Since the alternator is not outputting any power until it's spinning it gets a little help from the battery to get voltage/current to the armature until it can self-power and get the regulator operating. To eliminate the high-current path from the commutator the power is generated in the non-moving stator as 3-phase AC, that 3-Phase AC goes into a diode-bank of six diodes to convert the output to bumpy DC that is smoothed by being connected to a ginormous battery. If one of the diodes breaks you'll get erratic output. if the output will maintain at higher revs but not at lower revs it's almost always the slip-rings and brushes at fault (it takes less current at higher RPM to maintain voltage, at low RPM when higher current is needed, the brushes can't push enough current at only 14V so output falls).

The feedback loop for the regulator is completely internal you can't hook up anything to test it it works or doesn't, but you can replace the whole part. There are no moving parts in the power generating part of the alternator so it makes them crazy reliable.

I was very happy to have the Valeo brand in my x5 because that was the one i could find the $20 kit to refurbish the slip rings and brushes. The bosch i didn't see the slip ring kit and the regulators were more expensive also. The guy at Advance Auto was pretty blown away by my 150,000mile alternator testing like new.

It's so easy to remove/replace the regulator if it was my car i would take the alternator back out, remove the regulator and clean the brushes/slip rings. If they aren't terribly worn, re-assemble and take to Advance Auto to test before re-assembly. I would first determine if voltage is staying at 13.6 ± 0.4, if it is then it's doing it's job and the problem is elsewhere.

The previous post is perfectly detailed how to determine if the battery is properly holding a charge. Most people will not have a way to pull half the current out of a battery for 5 minutes so they won't be able to complete the test shown above, however you can take the car to a battery store for an under load test. They may be able to do the test shown (half load test after removing surface charge), they usually just do a full load test, but you can probably ask for a proper half load test like described above.

If one is going to be a DIYer, a good multimeter and a quality battery charger that will also load test a battery are essential.

Thanks everyone for being so helpful.

I took the battery out and took it to Advanced auto parts. They checked and said it was dead and refunded me the full price. The battery was actually two years old.

Battery was AutoCraft GoldBattery, Group Size 94R, 790 CCA