Anyone know what the signs of a faulty intelligent battery sensor on a 2004 545 are? I think it might be bad, but want to be sure before I spend the money on it.

I am also interested in this.

IBS is a Intteligent battery sensor and he monitor SOC ( state of charge ) and SOH ( state of healt ) for you battery.If this sensor fail you give an error in DIS and your battery is not charged correctly by alternator.
Best regards!

Heres the issue, when driving and changing gears, the interior lights will flicker, the sound on the radio cuts out for a second, and sometimes dynamic drive faults will pop up. If I disconnect the IBS, the problem goes away. I think the IBS is bad, but there are no faults stored. I am using carsoft to diagnose.

How do you disconnect the IBS, I might try that for a while.

Is there any side effects or potential problems from disconnecting it?

go in the trunk to the battery. on the negative cable, you'll see a small black connector with a single wiring going to it. i think it's wire tied to the negative cable. i disconnected it and the problems went away. no check engine light came on nor did it seem to hurt driveability at all. it did store a fault but never set the check engine light on. its weird because when it gets warm, with the ibs still connected, i don't have this problem. its only when the weather is cold. keep me posted on what you come up with

Some times you have to wonder if there is such a thing as too much intelligence. How did we all deal with our stupid, non-IBS, batteries and charging systems for the past 100 years? :whistle:

So this weekend my battery started playing up and I got the usual error messages, I disconnected the IBS on Saturday and have not had any issues so far.

Curious, with your engine running what is the charging voltage at the battery terminals? (~ +/- 14V DC??)

I will check it out as soon as possible.