Radio presets slowly disappearing?

[bfeng]

I did a quick search and didn’t see this topic discussed before.

Over the last week my 17 radio presets are slowly disappearing.
A few days ago 12-17 were gone.
This morning only 1-4 show up.

Anyone else experience this, and if so did you find a cause/fix?

FWIW, my battery is 11 Years old, and yet it tested out healthy 9 months ago when I brought it to my local auto parts store. The battery in our ML350 is 8 years old and it also tested out perfect. I can’t explain why these have lasted this long.

Other than this my 2011 x5d is running great.
At 130k miles I had front and rear control arms replaced and changed shocks to Bilsteins, and it drives almost like it did when new. Control arms seem to be good for about 60-70k before they wear out. Upkeep has been expensive (averaging $2000 a year in repairs after going out of warranty), but everything on this e70 works as it should (including the entire emissions system). Seems
Like this SAV will easily get to 200k miles.

[andrewwynn]

There is no such thing as a healthy 11 year old battery.

My 5 yr old battery would start my car at 10 below and "tested fine" at battery store but couldn't start my car after having hazard lights on for 8 minutes or charging an iPhone for 30 minutes.

Where you are somewhere that you can jump start the car leave your hazards on for 30-60 minutes and measure the vBat and see how long it takes to crank/start.

I'm willing to bet you have the same problem I had. Loss of capacity not loss of cranking amps.

When you have loss of capacity but can still deliver lots of amps to start you'll see the voltage drop to 10v or even less while starting. It will drop low enough to lose clock info and other stored settings.

[bfeng]

no such thing as a healthy 11 year old battery


That is s as m excellent point. The car part store only tests for high amperage and ignored voltage drop if s as MPs are high. V must have tipped low enough to screw up the electronics. I’m surprised BMW didn’t require electronic suppliers to build in the capability to bridge a short voltage drop. The cost to do that is minimal and almost inconsequential for devices which cost as much as an infotainment domain controller or head unit.

I’ll install a new battery and see if that helps. Our Ml350 has dual batteries (a smaller secondary). I wonder if the purpose is to keep V up for critical electronic subsystems…

John

[andrewwynn]

Newer than 2006-7 will have IBS and will log a histogram of how charged the battery was over time.

When my customer's 2008 328xi started having problems starting and would lose the time of day regularly I pulled the histogram just before replacing and it was horrible.

20% charge 30-40% of the time 40% 40-50% of the time. Never made it to 80% in the previous xx months. It was seeing that graph on a car that started find and ran great other than a few times it took two presses of the start button to get going that gives me the conviction to say it just sounds like end of life on the battery.

You will find that many many things go haywire when voltage gets low.

You need to check the current draw on start to make sure it's not too high lest you kill a new battery. (happens often)

[ard]

What tricky w BMWs is that they can 'starve' some components on the bus to conserve power for starting.



Batteries seem OK and start the car, but some items may drop quite low.


I have no proof of this, more of a hypothesis that seems to work in many situations.....

[andrewwynn]

There is proof out there I've read technical bulletin that describes exactly how you explained above.

I've also lived it in real-time.

More than once.

I've driven an e53 with non working Alternator up to the point it stopped working and it will in-fact shut down systems that are not mission critical to keep the engine running right to the end.

When the computers decide you only get forth gear it's time to pull over.

First you'll see the bat light blink then go solid and very quickly after that no abs/DSC.

[SB1120]

I say battery as well. 11 years is amazing! Most I’ve seen is 8.

My theory for the radio presets disappearing: the idrive system has a hard drive (I think in the dash) and does some read-write stuff each time you use the car. If you listen closely, you can hear the hdd running until around the time terminal 15 disconnects and everything goes to sleep. If your battery is exhausted (wouldn’t be surprised to see that code in the frm or other modules), power is cut early and so maybe the infotainment system doesn’t get a chance to back up data.

Is your climate control operating normally? On our ‘12, when the battery was failing, the defrost was the only way I could use the hvac until I replaced the battery. That was my first clue

On the note of the ML, from what I remember Mercedes used that smaller secondary battery for the alarm system so it would operate if the battery was disconnected, say by a thief.