Question on battery replacement

Hey guys,

Wife's 2008 328i has been having a problem for a few days where the clock gets reset (and displays "--:--" instead of the time) when the car has been turned off for some time. Doesn't happen all the time and sometimes the clock falls behind instead of getting reset.

Took it to my mechanic (not dealer) and he said it's because the battery is dying. That makes sense and I had guessed as much (even though there are no problems starting and the memory settings for seats, radio etc. are fine). But the odd thing is he said I need to take the car to the dealer to replace the battery. Apparently there's some calibration that needs to be done or something of the sort that can only be done at the dealer. He said a generic battery installed by someone other than the dealer will be fine for a short time but I'll start to see electronics issues like this pop up again after that.

Anyone else run into this? What's so special about BMW batteries and electronics systems that can't deal with the battery being replaced by someone other than the dealer?

It's important that the correct battery be fitted AND registered, so that it plays nice with the IBS (Intelligent Battery Sensor). While some independants can handle this, you are probably be safer having it done by a dealer.

Tom

Same thing happened to me and my 09 coupe last week. not only was the clock randomly get reset or goes 5 minutes or so slow per day, the things you will also observe happening include no more welcome lights, and no residual heat functionality after you turn off the car. Took it to the dealership and the battery was replaced under warranty.

The indy have good reason to get you to go to the dealers for this one. as the car will treat (use and charge) the battery based on it's condition and deterioration. So right now your car is using and charging the almost dead battery as an almost dead battery. if you just stick in a new battery, even if it's a BMW OEM battery, without having the dealership register it, the car will continue to think and treat the new battery as an "almost dead" battery. basically it's going to kill that new battery you put in pretty quickly. Registering it will let the car know to use and treat the battery as a new one.

the information posted could be correct, as I have had my 07-335 for only a few months, but seems odd to me that as smart as this car is that it cannot tell when the battery is fully charged? Most all new cars the Alternator has a regulator inside and sends a charge to the battery when it needs it and quits sending a charge when its fully charged.

If I had to replace my battery, I was going to hook a spare battery to the terminal under the hood to the plus and the negative to a ground and then replace the batter so I wouldnt loose all the presets in my car

tell me thats wrong?

Hondo

Originally Posted by emh

Hey guys,

Wife's 2008 328i has been having a problem for a few days where the clock gets reset (and displays "--:--" instead of the time) when the car has been turned off for some time. Doesn't happen all the time and sometimes the clock falls behind instead of getting reset.

Took it to my mechanic (not dealer) and he said it's because the battery is dying. That makes sense and I had guessed as much (even though there are no problems starting and the memory settings for seats, radio etc. are fine). But the odd thing is he said I need to take the car to the dealer to replace the battery. Apparently there's some calibration that needs to be done or something of the sort that can only be done at the dealer. He said a generic battery installed by someone other than the dealer will be fine for a short time but I'll start to see electronics issues like this pop up again after that.

Anyone else run into this? What's so special about BMW batteries and electronics systems that can't deal with the battery being replaced by someone other than the dealer?

All about that Here and many other threads.


.

Thanks everyone. Sounds like I'll just take it to the dealer and get the battery replaced.

As an engineer, this seems like bad system design to me. I don't see why the battery management system can't detect a sudden change in battery characteristics (as would be evident in a battery swap) and put itself into a learning mode that figures out what would be optimal for the new battery (instead of retaining what it "knew" about the old battery). Oh well... it is what it is I guess.

actually it is one of several "brilliant"' design features BMW have that are used to give the dealers more money. Buy and install it yourself and get the system update done at an independant shop, save a few hundred $$. Or better yet get the cable and do it youself, not rocket science, do a search in DIY section on the site for how to it info.
David

Originally Posted by emh

Thanks everyone. Sounds like I'll just take it to the dealer and get the battery replaced.

As an engineer, this seems like bad system design to me. I don't see why the battery management system can't detect a sudden change in battery characteristics (as would be evident in a battery swap) and put itself into a learning mode that figures out what would be optimal for the new battery (instead of retaining what it "knew" about the old battery). Oh well... it is what it is I guess.

Interesting! How would the ECU know how to charge a battery of unknown construction and capacity?

Originally Posted by CALWATERBOY

Interesting! How would the ECU know how to charge a battery of unknown construction and capacity?

In a modern BMW, it's not the ECU, but the IBS which would handle this function. So since it has to be told about new battery, perhaps it should be renamed the "Semi-Intelligent Battery Sensor?

Tom

IBS = Idiot battery system or Infernal Battery System.
It wakes up ever so often and checks itself thereby using more power
and shortening the life of the battery . Also if its so intelligent why isn't there
a simple way of changing the battery and telling it without having to hook
a computer up to it.

http://www.google.com/url?sa=t&rct=j...57700187,d.cGE

Originally Posted by David Williamso

actually it is one of several "brilliant"' design features BMW have that are used to give the dealers more money.
David

This ........ is what is going on here.

German MBAs have infected a great car company with the "razor blade" revenue model.

Like $500 NAV updates to the hard drive, ..... only BMW dealer can align your car, .... must buy ridiculous runflat replacement tires from dealer, ..... oh wait ..... software updates

Originally Posted by laser

This ........ is what is going on here.

German MBAs have infected a great car company with the "razor blade" revenue model.

Like $500 NAV updates to the hard drive, ..... only BMW dealer can align your car, .... must buy ridiculous runflat replacement tires from dealer, ..... oh wait ..... software updates

Not a single word of this -- including "a" and "the" -- is true.

Look the Intelligent Battery System takes a lot of variables into account for calculating how to charge the battery. It is not full proof and do you really think an AH difference if it is minor really matters? I think not given individual batteries have variance as well.
Also the registering the battery to let the IBS know you have replaced it is easily done with a labtop and a K+DCAN cable you can acquire on eBay or Amazon for not much cost.
http://www.e90post.com/forums/showthread.php?t=727091
The site above will take you to a member of another forum that has a download allowing you to register your battery for free. I have downloaded this software and tested it out on my 335 and it works just fine registering it.
I am not affilated with that members work at all but there are things you can do yourself.

Coding is also required if you are way off the AH rating of the battery you buy. However if you are close, good enough really.
There are You Tube videos out there that show you how to disconnect the IBS cable so you can remove the assembly without blowing a fuse.

Yes you can screw this up but if you are careful you should have no issues replacing the battery.
BMW uses two batteries vendors (Excide manufactured by Bosch by the way and Douglas). Find an Excide-Bosch/ Douglas battery that fits the AH and dimensions your BMW needs (stamped on the battery) and you should be good to go.

I do admit this is an unnecessary complxity because no one knows except BMW how much this improves battery life.

Locking your car is about the best way to help your battery since the ECU will turn on every 4 hours and ping your system, locked it doesn't turn on...

after market

dealer is a rip off

Originally Posted by CALWATERBOY

Interesting! How would the ECU know how to charge a battery of unknown construction and capacity?

Figuring out how to charge a battery of "unknown"* construction and capacity doesn't require black magic -- every manufacturer has been doing this for many decades now. And it's not like the IBS is significantly extending battery life over other cars. I'm guessing the complexity is in managing the various systems that run off the battery to minimize drain when the battery is nearing end of life. Even that is not unique to BMW.

Still, if a system wants to be intelligent about batteries of "unknown" construction and capacity, a feedback mechanism that monitors how the battery responds to whatever the system does, without requiring manual intervention, would be the right thing to do.

* They aren't really unknown construction and capacity, right -- as long as the manufacturer specifies what kind of battery to use, that narrows down the parameters greatly.

This is what the IBS does from the training publications the techs receive. I am looking for the detailed write up and will post that when I can find it but it is a lot more complicated than it need be.

Intelligent Battery Sensor - The IBS is a mechatronic intelligent battery sensor with its
own microcontroller. The IBS is connected to the negative battery terminal and is used to
measure battery terminal voltage, discharge/charge current and battery (electrolyte) temperature.
The information collected by the IBS is used to determine battery SoC and
SoH. This information is sent to the DME via the Bit Serial Data interface (BSD).

The IBS contains a micro processor that is used to monitor/measure various battery conditions
such as:
• Terminal voltage via measurement from B+ to Gnd
• Charge/discharge current via integrated shunt resistor
• Temperature of battery acid via integrated temp sensor
Index Explanation
1 Battery Ground Lead
2 B+ Connection for IBS
3 Bit Serial Data Interface (BSD)
4 Intelligent Battery Sensor (IBS)
Index Explanation
1 B+
2 B-
3 Battery Voltage Measurement
4 Battery Temp Measurement
5 Current Measurement
6 Microprocessor
7 BSD
8 DME/ECM

IBS Measuring /Evaluation Function
The measuring/evaluation function of the IBS electronics, continuously measures the following
values under all vehicle operating conditions:
When the vehicle is stationary, the IBS is programmed to wake up every 14 sec. and
makes the required measurements within approx. 50 ms in order to save power.
The measured values from the IBS are provided to the DME by way of the Binary Serial
Data Interface (BSD) to calculate the State of Charge and State of Health for the battery.
• State of Charge (SoC) is a calculated condition showing the current charge of the
battery. SoC is used during key "OFF" periods to insure the battery maintains a sufficient
charge to start the engine at least one more time.
• State of Health (SoH) tracks the history of the battery in the vehicle. Charge/discharge
cycles and times are monitored. SoH helps the DME determine the proper
charging rates and anticipated battery life. Internal resistance of the battery is calculated
by the IBS from the current and voltage dip during engine start. The values are
forwarded to the DME to calculate the SoH of the battery.
Software contained in the microprocessor of the IBS utilizes the measured values to calculate
the State of Charge (SoC) of the battery during vehicle sleep mode and compares
this information with that received from the DME/ECM pertaining to the battery SoC/SoH,
during the period of time between engine "OFF" and deactivation of the DME main relay.
The current SoC/battery data is stored in the IBS every 2 hours over a 6 hour time frame,
providing 3 - 2 hour snapshots of battery SoC information. The stored information/snapshot
data is overwritten every 6 hours. Whenever KL15 is activated the IBS updates the
DME with the current closed circuit histogram/battery status information, byway of the
BSD. Upon obtaining updated information the DME evaluates the new data and if a
closed-circuit current draw is identified a fault will be stored in the fault memory of the
DME.
• Voltage (6 V to 16.5 V) • Starting Current (0 A to 1000 A)
• Current (200 A to +200 A) • Temperature (-40°C to 105°C)
• Closed Circuit Current (0 A to 10


Here is the reference that might help on other E90 systems
http://www.bawarec.ru/manuals/3er/e9...3er-e90-12.pdf

Originally Posted by emh

Figuring out how to charge a battery of "unknown"* construction and capacity doesn't require black magic -- every manufacturer has been doing this for many decades now. And it's not like the IBS is significantly extending battery life over other cars. I'm guessing the complexity is in managing the various systems that run off the battery to minimize drain when the battery is nearing end of life. Even that is not unique to BMW.

Still, if a system wants to be intelligent about batteries of "unknown" construction and capacity, a feedback mechanism that monitors how the battery responds to whatever the system does, without requiring manual intervention, would be the right thing to do.

* They aren't really unknown construction and capacity, right -- as long as the manufacturer specifies what kind of battery to use, that narrows down the parameters greatly.

So, how's that done on an in-service battery? Or not done, of course - BMW supplies specs; we're expected t'adhere. Know how to check when battery's not in service, but how to have the CPU check when battery's installed & buttoned up.....

• Mfg declines to add vehicle weight & mfg expense with load tester
• Vehicle could easily check battery at every power down w/certain additions

If not exactly a match, provision's there for variance. Ya just gotta tell the ECU, battery adapter CPU, or whatever.


.

Originally Posted by hondo402000

the information posted could be correct, as I have had my 07-335 for only a few months, but seems odd to me that as smart as this car is that it cannot tell when the battery is fully charged? Most all new cars the Alternator has a regulator inside and sends a charge to the battery when it needs it and quits sending a charge when its fully charged.

If I had to replace my battery, I was going to hook a spare battery to the terminal under the hood to the plus and the negative to a ground and then replace the batter so I wouldnt loose all the presets in my car

tell me thats wrong?

Hondo

So at the point in time when you plug in the new battery you will have two batteries hooked up to the car simultaneously?

Originally Posted by Cultr

So at the point in time when you plug in the new battery you will have two batteries hooked up to the car simultaneously?

Pray they be in parallel.