Nice story P. But, as one mechanoignorant, I certainly would not worry about battery power within a reasonable range. More importantly, I would rather see a lower power condition on a built in gauge than wait for the iDrive or idiot light to tell me it is too late to do anything about (worse yet, get in and no start). But, as with everything: it is what it is and we all still like the vehicle enough to drop the $$ and spend time here chatting!

That said, if anyone wants to save a couple bucks (not much) on the ES5000 Battery booster Pack, look here: http://www.nationaltoolwarehouse.com...qx/product.htm
$125.94 + 9.99 flat rate ship to home (less to a business) and the flat rate applies up to 60 lbs and $400 (over $400 and under 60 lbs ships free).

In fact, they have a variety of different units: http://www.nationaltoolwarehouse.com...x/category.htm
and http://www.nationaltoolwarehouse.com...x/category.htm

I've been wondering how your voltage monitoring has been going. :thumbup:

Is it possible that the higher voltages in cold temps have something to do with recharging the battery after cranking over a cold diesel?

Can you confirm that the 35d charging system does NOT exhibit the voltage swings that one would expect if the charging system primarily charges during braking, idling etc and normally switches off during acceleration, etc. (AKA regenerative braking)?

T.I.A. - Funf Dreisig

I have not noticed that on my graphs, but it only samples the voltage every 5 seconds for recording, so it could possibly slip by. I have noticed an odd blip downward in the voltage every once in a while; however, it may just be a quirk of the OBD-II data buss or something.

The next time I go for a longer drive, I'll plug my realtime voltmeter in and monitor the voltage while braking and such.

I haven't been driving the X5 much since I don't want to get snow/salt/slush all over it while it is so new, and I've still got the old reliable 1992 Ford Explorer. I was hoping to get to 200,000 miles on the Explorer, but I've got about 2,000 miles to go and I don't think I want to take any long distances any more as it is rusting so bad bits and pieces are starting to fall off (I had to replace the brake lines as they had rusted through.) And the tires are just about bald. If I was thinking, I probably could have gotten a set of wheels and used tires pretty cheap when they were crushing old Explorers as part of cash for clunkers last year!

Take a look at the 4th listed failure. ?
SIB 611809

I bought a new '08 335i coupe two years ago. It has NAV, comfort access, no aftermarket anything.

SAME PROBLEM. I would get a low battery warning when trying to start the car. Occasionally when starting the car it would not respond when pushing the start button and there would be a warning signal that looked like a yellow lift indicating the car needed to be checked. The clock would also reset.

I just read this thread since I'm looking into an '11 X5. I almost laughed out loud as I told my wife about this thread, since this is exactly what I have experienced. I took my car to the dealer and they kept the car overnight for diagnostics, told me basically nothing wrong but "I don't drive it enough." This is the third car in my garage and I take it out about twice a week for a 10 mile drive, and a 200 mile drive every 2 weeks. Funny thing is I alternate cars and my Lexus RX and VW GTI don't have this problem even though they are driven the same amount. So I bought a battery tender and charge the BMW once every Wednesday. I'm thinking BMWs look and drive great but...

This is making me have serious thoughts about buying another BMW. I thought my 335i was just an oddball. Apparently not.

Thanks again for posting these SIBs.

So it appears that the BMW model E70-X5 computer is like all other computers. Occasionally they need to be reminded who controls the power cord :nanana:

So has anyone found the hidden Ctrl-Alt-Del button yet ?:rolleyes:

Funf Dreisg

Buy Back Trade Assist
 

In my case the X5 is still in the shop. NJ is running more tests and can not figure what is wrong. BMWNA will let me know in 3-5 days if they will do a buy back, trade assist. However I have had other issues besides this drain. All have taken years to sort out.

Bottom line there is an issue in at least some X5s that is chronic (3 batteries) and they do not know what it is. You can battery tend your battery and carry a reserve charger and get by but we do not do that in our 7 year old Honda Accord which runs like a top so we keep it. Why should I do it in an much newer SUV I paid $65,000 for?

Last time my SUV died by the way there was no high battery drain while park warnings the days or weeks before. Just a completely dead battery and auto. The battery was new last June.

I however would take a 335XI especially the new F10 or even a 550XI that I hear about. I would not take any thing made in SC. Sorry but I would not.

Happy to help. :thumbup:

I've being a victim of this excessive battery discharge issues since I pretty much got the car back in March 2010. My cars being into the dealership multiple times for this issue.

BMW keep's coming back to the same answer for me at least .... my driver profile. Admittedly, I do drive quite a few short distances in the city during the work week, but these are mixed with much longer trips at the weekend. 100+ miles.

Either way though, my car did not log any control module wake up errors ... and in any case they updated the vehicle software to the very latest configuration (per Jan 2010), but I've still seen the battery/clock reset issue. I don't have any aftermarket electrical equipment connected to the car, and I made a habit of removing any iPhone/iPod that might be charging from the car.

I think one day, the battery was so low, although the car did start, it caused all sorts of fun and games for the vehicles electronics for 1/2 hour or so of driving. The iDrive was going nuts !

Not sure what more to do at this point. Fortunately its never got to the point where the car has failed to start ... but it doesn't exactly inspire much confidence ... after all, you may find that if you leave the car for a extended period of time ... you might come back to a completely discharged car ! SUX!

Ummm... all 4 days? :stickpoke

Seriously when did you get your X5?

Funf Dreisig