Battery light on and drive go away

[uhenry1]

Hello,
My 2001 BMW X5 3.0 with 155,500 miles and all suddenly when start the car, the battery light is on and stay on until I drove about minutes then the battery light go away. The battery is about 4 years old and it a 60 months battery. Please I need your guy expertise advise. I can not break down because I got two young guy between 3 and 5 years old.

Thanks,
Uhenry1,

[thunderX]

Sounds like a bad battery; alternator sounds like it's OK since the light goes out after the alternator appears to be re-charging that bad battery.

[motordavid]

Replace the batt, for a start...several options of 'brand': Dealer, (not my pick), AutoZone, etc, etc.
A 30 min DIY, or a joint can do it for you.
If you need a good thread on DIY, with step by step and pics, let us know.
GL, mD

[uhenry1]

I drive my x5 today, the battery light constantly stay on and then my abs, airbag, etc include transafe light eventually the headlight, radio, and car stop. My of mine jump start but as soon as the jump start cable disconnect the engine shut off and my friend bring me the jump battery and connect to the battery jump cable and make it home before the battery is dead. I guess the alternator is bad. Do you know what kind of alternator do I need? DO you has the part number for the alternator.

Thanks,
Henry

[civdiv99]

Dude, slow down. Like the folks said, your battery is your first target, and if it's toast then that can give you a whole variety of symptoms that are not typical of your past experiences with a bad battery, and may not be consistent from one episode to the next.

The reason is virtually all functions are controlled by various modules, and the modules communicate with each other. Without going into detail, only a couple modules control; the others obey and run their little "departments." The communications is not at all high tech; it's basically the same as a 30 year old fax machine. But when the battery is flakey, then signal levels fluctuate or can go below minimum levels necessary for reliable communication between subsystems. Different systems will fall off the grid at different levels, and that can vary depending on specifics to that situation. The gotcha is that upon startup, there's a lot of handshaking going on as modules "roger up" with their status - and this is the same period of time when the alternator hasn't been brought fully online (depending on model, the system brings the alternator up (field current) after a short period of time so is not loading down the motor right at startup). And you have a perfect little storm, and what looks like all kinds of stuff going on.

First make sure you have a good battery; an alternator check is super simple, but don't go off in different directions - you hear hoofbeats, so ponder horses here.

Like someone said, a compatible battery in size and capacity can be had from a typical chain store. There's no magic benefit in spending considerably more to have one with a BMW sticker on it.

[Zulu95]

A quick trip to Advanced Auto, Autozone or Pepboys should tell you what is wrong. They can run a charging system/battery test and then you can move on from there. I would start where ever you got the 60 month battery fitted as you have warranty left on the battery.
FWIW I had an Exide replacement battery fitted just after we purchased the X in 2004 that is still going.

[neilrmp]

Originally Posted by uhenry1

I drive my x5 today, the battery light constantly stay on and then my abs, airbag, etc include transafe light eventually the headlight, radio, and car stop. My of mine jump start but as soon as the jump start cable disconnect the engine shut off and my friend bring me the jump battery and connect to the battery jump cable and make it home before the battery is dead. I guess the alternator is bad. Do you know what kind of alternator do I need? DO you has the part number for the alternator.

Thanks,
Henry

same issue with my car, I had to replace the alternator,belt and battery, I did it at the stealer for $1600, only because it happened 70 miles away for home and had it towed to the closest stealer..

[HoyaTerp]

Originally Posted by civdiv99

There's no magic benefit in spending considerably more to have one with a BMW sticker on it.

+1 that. I replaced mine with an Interstate battery and it was identical in every way to the original, even made in Germany. Cost about $200 less than the one with the BMW sticker.

And you're right, a weak/dying battery can really make the vehicle act psycho.

[civdiv99]

Ouch. That hurts clear over here..........

Originally Posted by neilrmp

same issue with my car, I had to replace the alternator,belt and battery, I did it at the stealer for $1600, only because it happened 70 miles away for home and had it towed to the closest stealer..

[uhenry1]

Thanks you for the information but I took my battery to recharge at the autozone and the battery is good, fully charge. Start with no problems but after long drive the battery light is on again.

Thanks,
uhenry1