Digital Clock resets to 0 due to low battery.

[archwerks]

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Does anyone else have a problem with the clock resetting because of driving many short trips in an urban setting? In my situation, xdrive 35i, The starter & accessories(navigation, ipod/phone, heater/fan, wipers, daytime running lites etc., draw so much power, that if most of your trips are shorter than 5 km, the battery draws down & does not get a chance to fully recharge. Subsequent starting keeps discharging the battery. Then the clock resets itself to zero overnite. very annoying!

Kojak mentioned similar thing.

[Kojak]

yes and after charging my battery overnight didn't fix the problem I went back to the dealer and suggested a battery replacement. I was surprised to find that they could read out an extensive log of all the low voltage events from the recent past from the diagnostic connector - they didn't need my description of what had been happening. After confirming what I had told him, the dealer cheerfully replaced my battery. Its been fine since but that is only 2 weeks. My car has been in use since mid may and has 10K miles on it. It took that almost that long to manifest symptoms

[xDrive50i]

Well you also have to consider the following:

Lets assume you have a brand new battery. The battery has a starting capacity of 100% at 25degC (77degF). That same battery only has a starting capacity of about 65% at 0degC (32degF), less than 40% at around -16degC (2degF) and at below -28degC (-19degF) it is less than 18%. All this is for a NEW battery. If you add other factors like age and higher temperatures during the summer time, the battery capacity diminishes quite a bit. If you only do short drives, the battery does not have enough time to get recharged to the point where it can sustain a voltage high enough for the on-board computer to work properly. The problem is also that in cold weather, the starter requires even more power to crank the engine over combine that with the lower battery capacity (due to temperature) and all the other power drain devices in your car, and it's no surprise that you are having issues. You should definately get your battery checked out by your dealer!

[Suzie's Dad]

Originally Posted by xDrive50i

Well you also have to consider the following:

Lets assume you have a brand new battery. The battery has a starting capacity of 100% at 25degC (77degF). That same battery only has a starting capacity of about 65% at 0degC (32degF), less than 40% at around -16degC (2degF) and at below -28degC (-19degF) it is less than 18%. All this is for a NEW battery. If you add other factors like age and higher temperatures during the summer time, the battery capacity diminishes quite a bit. If you only do short drives, the battery does not have enough time to get recharged to the point where it can sustain a voltage high enough for the on-board computer to work properly. The problem is also that in cold weather, the starter requires even more power to crank the engine over combine that with the lower battery capacity (due to temperature) and all the other power drain devices in your car, and it's no surprise that you are having issues. You should definately get your battery checked out by your dealer!

The 12-volt battery is living on borrowed time. I remember a few years ago BMW saying that they would like to move to 48-volt batteries due to the huge increase in electrics and electronics in modern vehicles, but they couldn't do it until the rest of the industry agreed to go along. As you say, starting places a huge drain on the battery, particularly in cold weather. Then as soon as you get going, on comes the heated seat, on comes the heated steering wheel, on goes the rear window defroster, on comes the radio, on go the lights,...

[xDrive50i]

Originally Posted by Suzie's Dad

The 12-volt battery is living on borrowed time. I remember a few years ago BMW saying that they would like to move to 48-volt batteries due to the huge increase in electrics and electronics in modern vehicles, but they couldn't do it until the rest of the industry agreed to go along. As you say, starting places a huge drain on the battery, particularly in cold weather. Then as soon as you get going, on comes the heated seat, on comes the heated steering wheel, on goes the rear window defroster, on comes the radio, on go the lights,...

Most car manufacturers still do want to move to a higher voltage but it is VERY slow coming....

It's actually 42V, I'm not entirely sure why they picked such a weird voltage though. 48V would have made more sense (IMHO) but it could have something to do with the chip manufacturing processes. Each process can only handle a certain maximum voltage before they have to go to the next higher process level, which increases cost significantly. I have to look into this a bit more...

Each lead acid battery cell has a nominal voltage of 2.0V. A standard car battery is comprised of 6 cells. The standard float charge is 2.25 to 2.30V per cell (13.5V to 13.8V for a car battery). A 'fast' charge is as high as 2.40V per cell (however you can not do this for extended periods of time or you wreck your LA battery REAL fast!).
On the other end, you have a 1.75V per cell cutoff point per cell (10.5V for a car battery). If you run the battery any lower than that, you run the risk of destroying the battery. A voltage past this point will SIGNIFICANTLY decrease the batteries capacity and/or lifetime. Some batteries are able to handle a 1.65V per cell 'low point' but require a re-charge pretty much right away. Anyway, enough technical stuff...

[archwerks]

My point is a car of this calibre that bmw wants to market in,w/the leaque of cayenne,range rover sport should not have this problem.
guess i'll have to go back to mercedes or lexus soon.

[xDrive50i]

Originally Posted by archwerks

My point is a car of this calibre that bmw wants to market in,w/the leaque of cayenne,range rover sport should not have this problem.
guess i'll have to go back to mercedes or lexus soon.

I do agree that certain aspects of the car SHOULD work flawlessly and should be exhaustively tested prior to product release, however I don't think there is a single car company in the world that does NOT have any issues with either new or existing car models. Buy a brand new MB, Porsche, Audi, Acura, Infiniti, Lexus or whatever other luxury car manufacturers model and you'll most likely end up having some kind of issue (not the same as you currently have, but for sure something else).

[archwerks]

u r right. My mb cruise control never worked properly. They replaced everything they could while under warranty, to no avail. in fact, some people recommend removing the cruise control unit from certain mb models altogether to rid themselves of an annoyance in an otherwise good car.
i know, everything designed by man has a fault in it, just a question of when it's discovered & how significant the fault is to the overall situation.
Shows to go u...good from far..but far from good...there's always something...

[Sammydtd]

Originally Posted by archwerks

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Does anyone else have a problem with the clock resetting because of driving many short trips in an urban setting? In my situation, xdrive 35i, The starter & accessories(navigation, ipod/phone, heater/fan, wipers, daytime running lites etc., draw so much power, that if most of your trips are shorter than 5 km, the battery draws down & does not get a chance to fully recharge. Subsequent starting keeps discharging the battery. Then the clock resets itself to zero overnite. very annoying!

Kojak mentioned similar thing.

I had the same problem, and it turned out to be a faulty rear climate control part that was sucking all the electricity...i think the first to suffer from the discharge is the clock, and if you were to keep it a few days without driving, then your entire battery might drain out...at least that's what happened to me!

[xDrive50i]

Originally Posted by Sammydtd

I had the same problem, and it turned out to be a faulty rear climate control part that was sucking all the electricity...i think the first to suffer from the discharge is the clock, and if you were to keep it a few days without driving, then your entire battery might drain out...at least that's what happened to me!

I wonder...

Sammydtd, I assume you have the optional 4 Zone climate control option in your X6?

archwerks and Kojak, do you guys have that option too?

[Sammydtd]

Originally Posted by xDrive50i

I wonder...

Sammydtd, I assume you have the optional 4 Zone climate control option in your X6?

archwerks and Kojak, do you guys have that option too?

You assume right, DVD player and 4 zone climate control

[archwerks]

I got everthing except hifisound,sport pkg,Rr dvd player.
Sport pkg. comes w/20" rims & diff. frt/rr sizes, too little for all the trouble. I'd go to the 21" later when more styles are available. Besides if i need snowtires, 19" rim is bettr being narrower.
Definitely, recommend active steer&adaptive drive for anyone getting the x6. Works better w/ dpc. Your passengers can get motion sickness w/o it if you drive in a sporting manner or in mountainous twisties.

[thread killer]

the majority of the charging from the alternator is when the car is coasting. yea sounds stupid, but its for gas milage.... same as the differential.... it (in a roundabout term) "overdrives" its self and sends power back up the driveshaft to make the car coast further......



so yes with little short trips the car never has time to charge the battery. the vehicle never has time to get sufficiant charge. your gonna have to put a trickle charger under the hood, (and my suggestion) to hard wire it to a plug in the grill so all you have to do is just plug it in w/o opening the hood. sounds stupid, but its just the way the car (among other new BMW's) are made.

[archwerks]

Took my car in on friday. Service dept put the battery discharge on a scope to monitor , all day... nothing wrong.
then Saturday a.m. they found something came on all by itself overnite and discharged the battery..so they need to find out what part is causing the discharge on Monday.
Will let u guys know what part it is on monday.

[thread killer]

those cars have normal draws for up to about 15 hours...... make sure they arent chasing their tail.....

a draw is something like over 500mA and for 20-30 minutes. its not just little spikes.



500mA spikes (TCU) and little-spikes-less-than-a-few-minutes-of garbage is normal for about 15 hours........ after that it needs to calm down under 50mA or so.


they might not figgure out what it is for a week or more. remember it takes the car an hour to go to sleep, and sometimes hours for it to show up, if it does. draw problems take forever sometimes to figgure out.

[archwerks]

Sounds like intermittent computer virus!
BMW needs to find a better supplier for these parts!

[thread killer]

no, its normal operation. you just dont understand the logic, which makes it sound like its broken.

[archwerks]

The part that governs battery charging or discharging under load is defective(discharging intermittently,when ignition is off). they'll replace it today.
will keep posting as situation develops.

[archwerks]

They should have an electrical readout on the battery condition, like in the old days. but in their wisdom, they've replaced that w/ an idiot light, and now not even a dedicated idiot lite. The car's computer did not even know there was a problem. The digital clock resetting was their idea of something's amiss. And only after i press them on the issue, Otherwise, we'd still be thinking that i drive too many short trips. 40 years since man went to the moon,& we still have battery issues. Maybe they need to put 2 batteries in just like the Bentleys.

[thread killer]

Originally Posted by archwerks

The part that governs battery charging or discharging under load is defective(discharging intermittently,when ignition is off). they'll replace it today.
will keep posting as situation develops.

so the DME? it controls alternator output.

Originally Posted by archwerks

They should have an electrical readout on the battery condition, like in the old days. but in their wisdom, they've replaced that w/ an idiot light, and now not even a dedicated idiot lite. The car's computer did not even know there was a problem. The digital clock resetting was their idea of something's amiss. And only after i press them on the issue, Otherwise, we'd still be thinking that i drive too many short trips. 40 years since man went to the moon,& we still have battery issues. Maybe they need to put 2 batteries in just like the Bentleys.

no, they need to increase the voltage. a 12 volt system just cant handle the electrical demands of newer cars..... unfortunately getting ALL automakers to do it and become standardized at 42 volts is hard to do. (why not 48V, i dunno)



and some BMW's DO have 2 batteries.

it still wouldnt help, just prolong the issue. the batteries are getting sufficantly charged.

[archwerks]

The service dept. replaced the IBS cable w/ the attached component that controls the battery's flow.
Hope that's the problem.

XDrive 50i:
Would u be able to locate the IBS cable on the parts cataloque like what u posted on the rear lite cluster?
Thanx.

[thread killer]

its the negative cable.