Battery drain protection/power save mode?
 

Hello, fellow X-fivers!

It has been a while since I've been here, mostly provided to how well my E70 ran for all this time :)

However, in the past couple of days it began to show some symptoms that I attribute to the failing battery. The symptom is that in the morning when the vehicle was not locked overnight, pushing the liftgate release button on the liftgate itself does not do anything. Then, when I open the driver's door, the whole dashboard lights up for a fraction of a second, then I hear the fuel pump pre-pressurizing the fuel-lines and the engine is ready to start. Once I start it, the computer complains about an excessive battery drain and the clock is reset. Well, the time is reset and the date appears to be lagging while the clock was not running.

The engine cranks up happily with no audible sign of underperforming battery, and it starts normally.

Does this all sound like a case of a battery getting ready to die? Does the E70 have electrical protection mechanism that puts the in-car electronics into a power-saving mode if it detects a chance of a battery draining below the level when the engine cannot be started?

I have the original 4-year old battery.


Regards,
/Sergey

^^ Yes, that is the exact way that my battery would behave. I got it replaced under warranty, swapped for one of the AGM batteries

time to change the battery

1. Agree time to replace

2. You'll be hard pressed to get it done under warranty.

3. The cost at a BMW dealer to BEGIN the diagnosis (only to be told 'it isnt covered') will exceed just buying a new one on-line.

4. You can have the dealer register the battery if you think it is needed, maybe $100.

I already called the dealer and had a bit of a "wow" moment when the quote came back at $597 for the whole thing. This is helluva lot of money for a battery. I'll have to explore alternatives...

ard,

What do you mean by registering the battery?

I had to change the battery after 4 years as well. Dealer charged about $450 including "registration". Dealer explained that "registration" is a programming step to ensure that the charging system is in sync with the new battery.

Search is your friend...LOTS of info on this. Why reinvent the wheel?

Yes.

Some folks skip this- you can replace the battery for ~<$200. At the numbers BMW charges, you'd need to get twice the life from a "BMW installed" battery to make it worthwhile.

Anyway, the dealer or ANY indy with a bmw computer can register a new battery. Call around and ask.

^^ Or you could do some reading figure out how to do it yourself.

That's what I ended up doing. I called a few shops and had everything replaced and registered for $200.

Sweet. Way to go