Battery Light Flickering
 

2006 X53 3.0L

So i noticed this afternoon when i started my car that the battery light kept flickering. When I started driving the flickering was intermittent.

I have been looking for away to determine if it the alternator or battery.

I just pulled my battery and I have:
Interstate Mega-Tron Plus
MTP-49/H8

The date appears to be L5, which to my knowledge is either Nov/Dec of 2015.

Is there a way to test if it is the battery vs alternator besides replacing one?

Amazing if it was made in 2005. Suggest you have it load tested. Most auto parts stores will do it for free. If you have a multimeter you can check voltage of the battery when car isn't running and when it is running. Battery should be 12.3 to 12.6 and with engine running it should be 13.4 to 13.7. Could also be corroded battery connectors. Not likely but could be low idle RPM. You can also read battery and alternator voltage by opening the cluster. https://video.search.yahoo.com/searc...6&action=click

Meant 2015(I edited)

Open cluster per you tube and got 11.6 when not running.

The only reason the battery symbol lights is because the alternator is on the way out.

As a result, the battery is not being charge correctly.

Either replace the alternator (or maybe just the rectifier/regulator if the slip rings and bearings are ok) the perhaps save the battery or wait a few weeks and end up replacing both the alternator AND the battery... :rolleyes:

BTW, when I state this, I'm assuming that the everything else in nominal. i.e. the alternator cables are OK and connected properly, the fan belt is on the car etc.! ;)

Replacing sounds fine.

I currently have a Bosch AL9413X alternator installed (140amp) is this unusual? I noticed most are the 120amp on the parts sites

Here is a remanufactured Bosch AL9413X from FCP Euro for $183 +$100 core charge. ECS Tuning also shows the Bosch AL9413X for $255 and does not specify remanufactured or new or no core charge.

https://www.fcpeuro.com/products/bmw...Lw_wcB#fitment

https://www.ecstuning.com/b-bosch-pa...6/al9413x~bos/

Since alternators are not cheap and it is not a quick repair I would verify the alternator is bad. What is the voltage with the engine running and bright lights on, at an idle and 3000 RPMs? 2015 is not so bad depending on the battery rating. I would have it loaded tested anyway.

Now that you've unlocked the cluster...you can also check the alternator using TEST 9 (just like you checked the battery)...except have the engine running. In fact, you can drive around with TEST 9 pulled up...take note of the charging systems voltage as you drive around...especially if the battery light illuminates or starts flickering while you're driving.

Since you have a 12 volt battery...the charging system (alternator) should be supplying more than 12 volts to keep the battery replenished and in a charged state (look for 12/5v-13.8...on average & possibly up to 14 volts occasionally while driving around)

The battery light...one of the most misunderstood warnings. The battery 90% of the time gets accused as being the culprit...when it's usually the VICTIM. :D