E46 - battery light illuminated
Discussion
Afternoon all,
My M3 doesn't get used much and the battery has been on its way out for a while. I've been jump starting the handful of times I used it last year, just to give it a run etc.
One such occasion was Christmas Day, I pre-charged the battery using a CTEK device and headed home. 15 minutes into the drive the battery light came on. Knowing the battery was weak, I turned around and stashed the car back in the garage.
Fast forward to today, I replaced the battery. However the red battery light is still illuminated indicating a fault in the charging system. I checked the terminals with a multimeter and the alternator seems to be okay, steady 14v when the car is running. I've taken it out for a run and the car seems fine. Heated seats etc all working as you'd expect.
Is it a case of running the car for a few days until it sorts itself out? Alternator was new last year so hoping that is not at fault. I had the multimeter connected for a short while to make sure the voltage was constant 14v+ which it was.
Thoughts?
Cheers,
Dan
My M3 doesn't get used much and the battery has been on its way out for a while. I've been jump starting the handful of times I used it last year, just to give it a run etc.
One such occasion was Christmas Day, I pre-charged the battery using a CTEK device and headed home. 15 minutes into the drive the battery light came on. Knowing the battery was weak, I turned around and stashed the car back in the garage.
Fast forward to today, I replaced the battery. However the red battery light is still illuminated indicating a fault in the charging system. I checked the terminals with a multimeter and the alternator seems to be okay, steady 14v when the car is running. I've taken it out for a run and the car seems fine. Heated seats etc all working as you'd expect.
Is it a case of running the car for a few days until it sorts itself out? Alternator was new last year so hoping that is not at fault. I had the multimeter connected for a short while to make sure the voltage was constant 14v+ which it was.
Thoughts?
Cheers,
Dan
Just a few words thrown out as I don't really know.....
Is the battery light indicating a fault in the charging system or (if it was a later car) "increased battery discharge" ??
I'm not familiar with E46 electronics, but E6x E9x etc have the facility to shut down consumers if the battery voltage is low for any reason. With the cold weather, there will be more stress on the battery, as well as more load with heated screen, seats etc. Hence the error message above.
Have you had any fault codes read?
I would have thought 14.2 or 14.4 volts would be a more suitable charge voltage for a discharged battery.
Does the car need to be coded for a new battery?
Is the battery light indicating a fault in the charging system or (if it was a later car) "increased battery discharge" ??
I'm not familiar with E46 electronics, but E6x E9x etc have the facility to shut down consumers if the battery voltage is low for any reason. With the cold weather, there will be more stress on the battery, as well as more load with heated screen, seats etc. Hence the error message above.
Have you had any fault codes read?
I would have thought 14.2 or 14.4 volts would be a more suitable charge voltage for a discharged battery.
Does the car need to be coded for a new battery?
AlwynMike said:
Just a few words thrown out as I don't really know.....
Is the battery light indicating a fault in the charging system or (if it was a later car) "increased battery discharge" ??
I'm not familiar with E46 electronics, but E6x E9x etc have the facility to shut down consumers if the battery voltage is low for any reason. With the cold weather, there will be more stress on the battery, as well as more load with heated screen, seats etc. Hence the error message above.
Have you had any fault codes read?
I would have thought 14.2 or 14.4 volts would be a more suitable charge voltage for a discharged battery.
Does the car need to be coded for a new battery?
No coding involved when my 54/ 2004 had a new battery. I just recall them slotting it in.Is the battery light indicating a fault in the charging system or (if it was a later car) "increased battery discharge" ??
I'm not familiar with E46 electronics, but E6x E9x etc have the facility to shut down consumers if the battery voltage is low for any reason. With the cold weather, there will be more stress on the battery, as well as more load with heated screen, seats etc. Hence the error message above.
Have you had any fault codes read?
I would have thought 14.2 or 14.4 volts would be a more suitable charge voltage for a discharged battery.
Does the car need to be coded for a new battery?
I never had any red warning light either, just the typical gremlins like radio not working and then it died. Was original one too. Lasted 12.5 years.
Made me wonder if whatever sensor 'speaks' to the car about batter is faulty. But not being too mechanically minded I don't even know if there is one.
The more I think about it, the more I think about the amount of times I've driven cars with low batteries and never seen the battery light before.
Speaking to a friend earlier reminded me that this is not the first time the light has come on. 6 months or so ago I was driving at night and had the light come on shortly after turning the heated seats on.
With the alternator replacement, I do hope the previous owner got the right amp rating. I remember on my E36 there were so many variants, directly related to the spec of the car. Convertible with heated seats are at about 140a from memory, where as some of the cars had 75a. I might have a look to see if I can read the rating of this one. Surely I can't be using that much energy though? It's a tin top coupe.
I'll be daily driving it this week so will report back, will also stick some jump leads in the boot.
Speaking to a friend earlier reminded me that this is not the first time the light has come on. 6 months or so ago I was driving at night and had the light come on shortly after turning the heated seats on.
With the alternator replacement, I do hope the previous owner got the right amp rating. I remember on my E36 there were so many variants, directly related to the spec of the car. Convertible with heated seats are at about 140a from memory, where as some of the cars had 75a. I might have a look to see if I can read the rating of this one. Surely I can't be using that much energy though? It's a tin top coupe.
I'll be daily driving it this week so will report back, will also stick some jump leads in the boot.
If the alternator was repaired or re-cond but not new I would be looking no further than this part TBH , charge light is not a battery condition/charge indicator it just tells you alt is giving no output , chances are you may have a faulty/failing voltage regulator in the alternator , obviously the normal caveat applies concerning wiring loom condition, its terminations etc
What brand of alternator is it?
If it's an RTX from ECP it may be giving a false light ; I've seen it a few times now.
My battery in my M3 is getting close to replacement and the battery light has never illuminated a light when running until the alternator was borked ; I've not seen on previous cars either with an alternator. Mine went intermittently but when the light was on the voltage was also down ; likewise, the light was off when it was back to 14.4V again.
FWIW the battery in my M3 is now 15 years old ; it's the original battery. When I got my alternator it was a 120Ah item. According to RealOEM both the Convertible and Coupe have the same item:
http://www.realoem.com/bmw/enUS/showparts?id=BR93-...
If it's an RTX from ECP it may be giving a false light ; I've seen it a few times now.
My battery in my M3 is getting close to replacement and the battery light has never illuminated a light when running until the alternator was borked ; I've not seen on previous cars either with an alternator. Mine went intermittently but when the light was on the voltage was also down ; likewise, the light was off when it was back to 14.4V again.
FWIW the battery in my M3 is now 15 years old ; it's the original battery. When I got my alternator it was a 120Ah item. According to RealOEM both the Convertible and Coupe have the same item:
http://www.realoem.com/bmw/enUS/showparts?id=BR93-...
Edited by SebringMan on Monday 15th January 10:06
Morning chaps.
Not sure about the brand of the alternator, it was just mentioned at the time of purchase. I've had problems with cheaper alternators in the past too.
Thanks for the replies anyway, but I have surprising good news! No battery light at all this morning. Stuck a fair few accessories on (HK, heated seats, xenons etc) without issue.
One thing that might be worth noting is when I unlocked the car yesterday morning (it had been in the garage since Christmas Day), the door unlocks etc were very slow so I knew the battery was weak. As soon as I opened the drivers door the alarm began to sound. Never had that before, definitely the quickest battery change I've ever done though!
Could it have been the aux battery took a hit from the alarm sounding, and levelled itself out overnight? It would be good to know what exactly the battery light can mean. Is it just there to indicate a fault in the charging system? I'll double check the terminals and earths if it pops back up.
For now though, happy to bury my head in the sand and see how it goes throughout the week.
Not sure about the brand of the alternator, it was just mentioned at the time of purchase. I've had problems with cheaper alternators in the past too.
Thanks for the replies anyway, but I have surprising good news! No battery light at all this morning. Stuck a fair few accessories on (HK, heated seats, xenons etc) without issue.
One thing that might be worth noting is when I unlocked the car yesterday morning (it had been in the garage since Christmas Day), the door unlocks etc were very slow so I knew the battery was weak. As soon as I opened the drivers door the alarm began to sound. Never had that before, definitely the quickest battery change I've ever done though!
Could it have been the aux battery took a hit from the alarm sounding, and levelled itself out overnight? It would be good to know what exactly the battery light can mean. Is it just there to indicate a fault in the charging system? I'll double check the terminals and earths if it pops back up.
For now though, happy to bury my head in the sand and see how it goes throughout the week.
You could try cleaning out the plug on the back of the alternator and giving it a clean. However, I'd expect it not to be charging too. It may be worth putting the multimeter into AC mode to see if you have a ripple from a diode going bad; I doubt it would put the light on but you never know.
I'd just say it's the car's way of saying it's got soul.
Do you have INPA? That may shed some light on the matter.
I'd just say it's the car's way of saying it's got soul.
Do you have INPA? That may shed some light on the matter
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