I'm with Penguin, and in 8 yrs worth of trickle charging through those
under the hood lugs, (including some 5 month long inactive seasons), I've
never had a prob with using the lugs for charge point. Charging to the
battery terminals requires some unbolting effort; doubt many dlr sales
guys could get to it. :rofl:
GL,mD

I dropped off my 08 X5 for 1st oil change on 13k miles at dealer this morning and also mentioned to my adviser about high batter drain message I got couple days ago. Advisor just called me and said there may be a short circuit casuing the high battery drain :dunno:, will keep my car for over night to test to confirm.

Keep you guys posted!

my turn to chime in on this issue! Wife goes to start the X yesterday evening and it doesn't turn over. She call me freaking out about the X not starting and I told her to call Roadside assistance. (luckily she was in our drive way and not somewhere on the road)

Any ways they send someone out for a boost and wha-la power! But then the emergency brake won't disengage. End up having to get the X towed to nearest dealership on dollies.

After a couple of hours SA comes out and tells me the battery is no longer good and that issues is "Unfavorable Driver Profile" and basically to frequent short trips in a small amount of time. Here's the kicker...NEW BATTERY WOULD NOT BE COVERED UNDER WARRANTY, COST $550. When I heard that I absolutely lost it and called BS on the whole thing. A $75K plus vehicle shouldn't be going through this!

I got on the phone with my usual dealership and they told me to get out of the dealership I was in and head over to them. My usual SA promised they would cover it. So we'll see what happens!! Sorry for the rambling but its been a tough day!!

There needs to be a better solution from BMW for this!!

I still use my 1992 Ford Explorer with almost 200,000 miles on it to drive one mile to the coffee shop every day and one mile back. That's the only use it gets any more.

It has no battery/charging problems.


You are correct -- this is BMW BS. The BMW design engineers clearly have put an inadequate charging system in the E70, and as usual with the stubborn Germans, it will take then at least another year or two to admit it and fix it with either a higher capacity alternator, or some tweaks to the charging system to charge the battery more aggressively. The X5 alternator is rated at 180 amps and should be able to keep the battery charged, even with short trips.

Alternatively, they are having quality problems, with the most likely being alternators with lower than rated output.

I'm having second thoughts about the X5 I have on order, but I do know one thing -- the first accessory I'm going to buy is a portable battery jumper to keep handy in the back!

A sad state of affairs, and one I hope BMW NA puts a high priority on solving. Having a lot of X5 owners telling their friends that their $70,000 X5 cannot handle short trips is not going to help their sales.

Seriously, this is as if we are back to the 1950's/early 1960's when we still used generators rather than alternators. It appears BMW X5s now have electrical systems where the functional performance is equivalent to a 1958 Chevy.

Does anyone else find it just a bit ironic that the E70 is so smart that it can schedule conditions based maintenance with the dealer and collect/record enough information to produce an "Unfavorable Driver Profile" report on short trip drivers; Yet it is so stupid that it will strand these same drivers with a dead battery, without so much as a warning message? What is this, revenge for not driving it enough? :rolleyes:

Funf Dreisig

Bingo.

There is no reason the charging system should not be able to keep the battery charged, even if the engine just idled. BMW may have some sophisticated algorithm to maximize efficiency by trying to only charge the battery when the engine is decelerating; however, it should also be smart enough to maximize the alternator output if it is sensing the battery charge is not topping-up. Alternator output is dependent upon RPM (not as much as the old generators), and BMW might simply be using too large of a pulley on the alternator. Some people use what are known as underdrive pulleys to slow the alternator speed to reduce the load the alternator puts on the engine (considered a performance modification.) I wonder if something as simple as a smaller alternator pulley to increase the alternator speed at low engines speeds would solve the problem of short trips.

I do tons of short trips. I have 8750 mi. after nearly 2 years. I drive my wife to the station about 1.5 mi. down the road and back, then do it again at 5pm everyday. That's it for weekdays. If that's not frequent short trips, I don't know what is. I've only seen the battery drain message twice though.

Well that's twice more than I hope I ever see :)

But seriously, stories like yours make we wonder if the underlying problem its more an issue of high battery use options (e.g. comfort access) and usage patterns (e.g. leaving it normally locked vs unlocked) that is exacerbated by short trip driving. And the reason short trips get blamed, is that is the info the dealers can get out of the OBC logs. Besides it's an easy excuse that puts the blame on the driver not the X5 design/implementation. :(

FWIW I agree that a well designed charging system should handle any reasonable options/usgae variations. And a bigger/better alternator may be be easiest "cure". But it would still be nice to know whether some X5s are less likely to experience these problems due to options etc.

Funf Dreisig

one possibility is that the engine needs to reach a certain RPM to charge. I don't know about cars as i haven't really worked on a car charging system, but I've worked on my bike's(ducati). the Ducati would only charge if you're above 4000 rpms and below 7000rpm's the reason being the alternator wouldn't put out enough voltage for the voltage regular to convert into a consistent 14V current to charge the battery. so if you leave a ducati at idle for a long time, it can actually drain the battery and kill itself. but that could just be beacuse motorcycles have limited charging systems due to minimizing weight

Correct. So the manufacturer picks an alternator pulley size so that (a) the maximum RPM of the alternator design is not exceeded, (b) the output is sufficient to charge the battery under "normal" engine RPM usage profiles, and (c) doesn't spin faster than necessary, on average, to be less of a drag on the engine and increase economy/HP.

It seems to me that a couple of possibilities are that BMW:

(1) Went to far on the "efficiency" end and put too large of a pulley on the alternator (larger pulley = lower RPM) to lower average parasitic load, and/or

(2) Went too far with their efficiency strategy of only charging the battery when the engine rpm is falling/throttle is lifted, (sort of like a mini brake regeneration concept).

Just some speculation on my part...