help with charging problem

i just bought a 02 bmw 745li about a week ago and it is already turning into a nightmare. love the car its beautiful but im stuck. my battery gets so hot it smell the whole cabin with that acid smell. figured the alternator was overcharging so i put a new alternator in it and the problem is still there. my battery and alternator both test fine and appear to be charging correctly but when i drive more than about 20 miles it seems to be overcharging still. is there any ideas of what problem may be i thought about taking it to bmw but no it will be a several hundred dollar trip and they may or may not find the problem. it seems to charge fine when we test it and battery tests good and dynamic control inactive pops up. the weird thing to me is that yesterday i drove 40 miles and it didnt do it but did it earlier in the day driving 20 miles

How many miles. Also it is a problematic car, just look at my signature..

i read yours and really wish i would have put a little more thought into it before buying it has 108,000

Originally Posted by rlsmead

i read yours and really wish i would have put a little more thought into it before buying it has 108,000

I would highly recommend getting an extended warranty through carchex. Those repairs below were covered by the warranty. including when my tranny goes out soon which tends to go out around 80,000 miles.

how long have you had yours 13k in a year thats sad i didnt pay that for the cari will be in a world of hurt if repairs end up half that my alternator was $1000

what do the warranty's run $$

I've had mine since January, it's been in the shop every month except October (because I wont drive it this month) and July. I'll have a brand new car by mid next year as all components should be changed by then. Serious extended warranty for 208 a month for 18 months to get full coverage for 4 years isn't a bad investment.

check if vent tube on battery maybe it is bad and make sure u have right battery AGM possible that previous owner could install wrong type of battery.

i checked it and it hadnt been hooked up but that still doesnt make sense for it to get so hot. and it is a bmw battery i believe it is agm

change the battery and register it first

Originally Posted by Khabar

change the battery and register it first

+1
Since you changed the alternator already, like Khabar said, I would change the battery and have it registered (very important part). Maybe the previous owner failed to do so which can result in over/under charging and reducing the life of the battery. You can get the batteries online for around $200-$250. Then find a good independent shop (aka INDY) to register it.

Originally Posted by wayne86

3-4K. But be aware, youll only get a max payout of the warranty based on the value of the car when you get the warranty. In your case max payout might be only $7K based on NADA Guide. Thats said, if you get more then you pay for the warranty it probably worth it for these cars. Review the Carchex warranty contracts they have online and read the fine print and call them to be clear on what is covered and the limits of payout. Im sure they would not cover preexisting problems. Also you have to wait like 30-60 days before the warranty takes effect......this to help limit people from claiming preexisting problems on the warranty.

They valued mine at 17,000 you can ask before you purchase.

ill put a new battery in today and see where that puts me i suppose. hopefully i can get it worked out iv never owned a bmw and this is such an odd problem

register it also otherwise no point of replacing it.

ya ill do that for sure. maybe its as simple as that. hoping that fixes it

Originally Posted by rlsmead

ill put a new battery in today and see where that puts me i suppose. hopefully i can get it worked out iv never owned a bmw and this is such an odd problem

Putting it in is 1/2 the task, you need to get it registered. My 7 is my first BMW as well. When I first bought it, it needed a battery. I have to admit this forum does scare the newcomers but also is a big help. I come here everyday, for a laugh, chime in with my two cents, or for help. Either way the folks here are awesome always willing to help. I would like to welcome you and together we all get thru our "issues" together.

absolutely i been reading for about an hour thinking i bought a 5,000pound beautiful paperweight but this is allot of help do you no the difference in the agm battery and the typical

AGM is more stronger, durable, better for power hogs (like our 7's).. I'll have to look for a better description.