[///mChris]

All,

I successfully updated the software in my headunit. My first attempt with ISTA didn't work as my Noco 10A charger in power supply mode doesn't have enough amperage to keep the ignition on. My power meter shows it requires about 20A to keep the ignition on. I built a power supply as seen in post
https://www.e90post.com/forums/showt...0#post31703500

The software update took about an hour to finish.

[c0riolis]

FYI you shouldn't be powering the car directly from the battery, use the engine bay posts instead has they have built-in protections.

[///mChris]

That's good to know. Do you have any details on the protections built in? I wonder if there are wiring diagrams somewhere.

[c0riolis]

If you directly connect to the battery it bypasses the IBS (Intelligent Battery Sensor). I do not have the details on what built-in protections it has, but it's explicitly called out in multiple sections of the workshop manual:

If the battery is charged while it is still installed: always connect the charger to the jump start terminal point in the engine compartment.

To prevent the intelligent battery sensor from malfunctioning, use the charging points in the engine compartment.

[c0riolis]

Some more infos:

The IBS continuously measures the following values on the battery:

• Terminal voltage
• Charge current
• Discharge current
• Battery temperature

If the battery is to be charged while it is still installed, it must be charges using the jump start terminal points. Only then can you be sure that charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS). If the battery is charged directly at the battery terminals, this could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries.

[///mChris]

That's super helpful. Thank you.

I put a battery tender in the trunk as well. Luckily the post I used is on the other side of the battery managment module.