Alternator issue?
 

Lent my 4.6is to a mate whilst I'm away. He called me today to let me know that the car struggled to start initially, and warning lights flickered briefly - problem now is the damn battery light stays on, even though the car drives fine. He drove the car for 20mins - turned off for 30 mins then restarted - all good except the battery light remains on !!!

Since then he left the car for 2 days and he told me it started ok 1st time of asking, but battery light is still on.

Weird thing is that 3 weeks ago I turned the car off but the Auto headlights stayed on, until I had to restart/switch off the car a 2nd time.
I can't sort out this issue until I return at the end of Feb, so 2 questions:-
- Is it safe to drive the car?
- does this sound a battery/alternator/some other issue?
Cheers

HI. Just to add, if it is not an alternator issue and all seems well, is there any way to reset the red battery light?

Thanks.

An update - after 1 week the car does not start, but the lights seem to be working ok (for now). Decided to replace the alternator and saw the folowing on Ebay - which one would you choose? Thanks.

BMW X5 4.6is E53 £220 WATER-COOLED ALTERNATOR Bosch OE 150amp 2A167 ABBCO Luton | eBay

or

RTX Alternator For BMW 5 & 7 Series & X5 | eBay

I have had this problem for the past year. I had the alternator rebuilt and every 2-3 months I either have the battery light, and/or the deadly triangle (abs/red brake light/dsc). It is the alternator. New alt is about $900 for the part or 450 for a rebuilt from a auto store that they have to order. At this is for a 2001 e53 water cooled. Easy to replace but extremely expensive.

Thanks Drkenigma1. Would you recommend buying a new alternator in this case or to buy a rebulit one? - the Ebay links above show sellers that have 100% +ve feedback in the 100's so I'm thinking of buying a Reman alternator.

You mentioned that your bettery light came on every 2 months - how did you get rid of the light?

Thanks.

Well funny that you should mention that. I now have the battery light on, which means a charging problem. I called several BMW dismantlers and local shops. They told me that this cannot be rebuilt. I am like you and have to buy one from somewhere else. The only way out of this pickle is replace it from a dismantler or retailer. I am going to buy on from Ebay. My light when out when the alternator is replaced and battery is charged. I think that my coolant leaking problem (valley pan) may have something to do with it because it is water cooled.

So will you be buying a new one or still sticking with a reman, as you had problem with your rebuild? I am tempted to buy new one, but the price tag is very steep - not sure yet!