BMW MY08 X5 Battery Problem

[Ron07x5]

Yes a lot of short and.level trips setup for a deeply discharged battery and recharging from deeply discharged kills batteries. My wife.works from home.and.when she uses.it.Will.drive.a.few.miles.to.the.store.or.gym on level.ground. I have.a.330I and.drive.just.like 2 miles.to.work. so maybe 6000 miles on each car.for.a year with some.signify can't.distance.traveled.on.some.weekend.in one.of.the cars. So I just.got.the x5 and now.realize my low mileage use does.fit.the charging.system .... hence.my plan.to manage.the battery and.plug.in.the car. It.is a.stupid.design that.Will not.keep.the battery at.75percent at least. I am a firmware software engineer.with many years.of.experience .... hey bmw it.isn't.serving your.customers.well!

[lanbrown]

BMW is not alone is battery issues though, other manufacturers have issues as well. They are putting more and more electronics in but the charging system hasn't really changed. This causes issues. Did BMW make some poor decisions that other companies didn't make? Sure, but they also made some decisions that are better than what others have done.

There was talk of 42-volt electrical systems in the 90's. Those obviously never materialized. in 2011 the Germans manufacturers agreed upon a 48 volt system.

A few things BMW should have done for N63 based vehicles. When you pushed the park button, the alternator should have engaged (unless that battery was already at 100%.) While a second or three would not do much for the battery system, a bit of power would have gone into it. Next, they should have activated the cooling fans to help draw air through the radiator and expel hot air out from the engine bay compartment. This should allow the cooling system that runs after the engine is turned off to run less; how much is debatable but every bit helps.

To help cool the turbos on the Ford Ecoboost 3.5l V6; after the engine is off, cooler coolant is automatically circulated through the turbo because of their setup. BMW is using electrical pumps to do it. I'm sure the BMW method is more effective at removing heat, but it is at the expense of the electrical system.

[koolkat1973]

I went ahead and bought another brand new battery today from BMW. Hopefully - the Autocraft battery was the culprit even though AAP technician told me battery was good.

[Ron07x5]

Originally Posted by koolkat1973

I went ahead and bought another brand new battery today from BMW. Hopefully - the Autocraft battery was the culprit even though AAP technician told me battery was good.

So now it will work fine for some months, the question is how will it be in 6 months?

Answer these questions ...

1. How many miles a week do you drive?
2. Are a lot of these miles at night?
3. Are the roads flat or nearly so where you live.

Reasoning for questions ...

I repeat the car ONLY recharges the battery when coasting and that happens only lot when going down hills.
Drivng a car at night means you have the lights on ... lights use more power!
If you drive few miles from home to wherever you use a lot of juice powering up and starting the car and when you don't drive far ... enough coast-charging doesn't occur.

Note the voltage reading on the battery when you first install a fully charged battery (write it down) ... not how it drops a little lower every week?

[Ron07x5]

Originally Posted by koolkat1973

So I repeat the entire process of locking the door, waited, then unlocked the door and the same thing happend. Voltmeter reading went from 12.4V to 9.1V within 30 seconds to minute after unlocking the car. Is this a sympton of a bad battery? I'm clueless at this point what the issue would be and how a battery can go from 12.4V to 9.2V within a minute. Please help.
Thank you.
Kiet

You need a means of measuring the current (amps) draw when the voltage takes the plunge! Guessing ...
Your battery has NO stored-reserve to give so when you unlock the car ... the car systems power up and there isn't enough "juice to give"? 9/2v and everybody would be flaky! So you battery has no power reserve. Either the battery isn't charged or it can't hold a charge anymore?

What does the autoparts store think of the battery now? Do they think it is fully charged, can they tell? My guess is another fully charged battery and everything works great.

My guess is you do not drive many miles and the miles you drive are flat ... so little coasting to charge the battery.

Anyway another new charged battery and it will be fine for about as long. Could be the battery wasn't introduced-setup correctly to the X5? Could be a bad battery from the beginning but I doubt that.

[lanbrown]

That is not correct in that the car only charges when coasting. The system charges the battery but will decouple the alternator from the engine under acceleration or when the battery reaches 80%. If you are braking, coasting, etc. if the battery is not at 100%, it will then couple the alternator back into play.

Watch the video:
BMW EfficientDynamics : Brake Energy Regeneration

The bigger issue is that the battery is never getting fully charged. Short trips do not replace the amount of energy consumed by starting the vehicle. If you do a lot of short trips, BMW recommends that you either buy a battery charger or go for a long drive. If the alternator only worked when braking or coasting, then why would a long drive help? You could drive until you ran out of fuel and no power would have been put into the battery. The N63 issue is a little different. You have that the battery will probably only see 80% charge, but when you turn the engine off you still have the cooling system operating. Keep in mind that many manufacturers use a mechanically driven water pump; BMW is using electric. So how much energy is being used for the pump to run and how long is it running after the vehicle is off? You also have that after you open a door and get out, if you don't lock the vehicle, the radio is still operating. Once again, consuming power. Pathway lighting is also running. Then you have the normal items that are always drawing power; comfort access/remote receiver, etc. So even if the alternator only charges to 80%, you need to drive far enough to let the alternator charge the battery to 80%. If you only get it to say 75% on day 1, then 70% on day 2, then 65% on day three. You are not driving far enough to actually help. If you make a 5 mile trip and there were four stops, how could you ever actually charge the battery up? Especially if the cooling system is running the entire time.

Ford uses a different system so that a turbo timer isn't required. BMW doesn't use the same system as Ford but once again, they didn't want to use a turbo timer. Ford has battery issues of its own, it just may not to be the degree of BMW. Ford also isn't using electric water pumps, etc. A larger alternator might be beneficial for BMW to use. This way shorter trips when the battery is below 80% it can provide more power to charge the battery.

[Ron07x5]

FYI ... I believe my newer BMW battery will become discharge with our lite use of the X5 and I believe we can ruin a battery sooner this way. My plan .... I have showing up tomorrow a cigarette lighter "voltmeter" etc. called A "Jebsen 4in1 car charger" for $11.99 via Amazon. I will monitor the batter voltage with this! I will then fully charge the battery using a 021-0123 I already have for my boat.
And then I watch the voltage at rest. I suspect the x5 voltage will drop over weeks and as needed I will charge the battery weekly or bi-weekly? To make this easier I may need to install a plug in my x5 grill to go to directly to the battery "jump spot". At any rate ... I will not see the battery harmed or have the car ... strand me or my wife. I won't even let the X5 confuse me with failing systems because they aren't working right because of a low battery ... go figure.
I am a engineer this isn't rocket science but it isn't it just it works either! Shame on BMW for making such a stupid flawed design here!

[Doug Huffman]

Originally Posted by Ron07x5

[ ... ]I am a engineer ... !

I recommend BatteryUniversity.com by Cadex Electronics Battery analyzers, chargers, rapid-testers and monitoring systems | Cadex Electronics

[koolkat1973]

I've noticed that my alternator takes about 30 seconds for it to kick upon start of the car. Is this normal for the X5? In my other two cars, the alternator kicks on immdiately upon startup. Thanks.

[TiAgX5]

I do the same Ron07X5.

Cigarette lighter volt meter, smart charger if the X sits for more then 3 days.

I also replace the battery when voltage drops to 12.2 after sitting for 2 days.

12 yrs/200k miles and still on OE alternator, OE battery lasted 8 yrs, Autozone battery 4 yrs, just installed a Bosch unit.