Causes of flat batteries on BMWs explained - Great guide!!

If you own an older BMW, no doubt you will have experienced your battery suddenly starting to go dead for no apparent reason. All modern BMWs have a ‘shut-down’ procedure after the ignition is turned off, things can be heard whirring and humming even after you’ve locked the car and this is the most common cause of your battery going dead over night with no warning, but there are others too...

Below is a great guide from Vlad at MCA Blog explaining the reasons BMW batteries go flat over night and where to check. It also details that bane of the BMW battery's life, the 'IBS' or Intelligent Battery Sensor fitted from the '90s on. 

https://mca.electricmura.ro/en/blog-bmw-what-causes-dead-battery/

• Plugged in external devices
• Plugged in OBD-II scanner
• BMW Intelligent Battery Sensor
• The infamous ”hedgehog” (from the climate control panel)
• One of the electronics on your car drains too much power or does not go into sleep mode
• Faulty alternator
• Old battery

BMW IHKA Heating and Air Con. System Technical Manual / Trouble Shooting [PDF] [E65/66, E53 X5, E63/64, E60]

Detailed 55-page guide on the operation and design of the IHKA climate-control / heating / air-conditioning system that started in the E65 7-Series and made it on to succeeding models such as the E60 5-Ser, E63 6-Ser and E53 X5. The latter of which I obtained the guide for to help in diagnosing problems with a noise secondary water-pump.

LINK: https://drive.google.com/file/d/1KBG3_annWcqTekn5NyhKVFqcXzCq2P_X/view?usp=sharing

Contents:

IHKA Automatic Heating and Air Conditioning System
Objectives of the Module . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .2 
Purpose of the System . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 3 

System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Air Conditioning System
System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..11 
Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 
Workshop Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Heating System
System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

IHKA Heater and Air Conditioner Housing
System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  .19

Control Panel/Control Module
Detailed Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Temperature and Air Flow Control
Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 27

Air Distribution
Principle of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . .35

Stationary Functions
Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 45

Non-Air Conditioning Functions
Rear Roller Blind Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . . .48

Coding
Key Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 
Vehicle Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 
Workshop Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

ReviewQuestions . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .55

Objectives of The Module
After Completing this module, you will be able to:
• List the gasses detected by the AUC-2 sensor.
• Explain how the refrigerant compressor output is varied.
• List the refrigerant compressor “Run In” procedure.
• Locate the blower motor and blower control module.
• Describe the control panel functions.
• Explain the “Y” factor.
• Explain how the temperature is increased during air conditioning operation. • List the functions that apply to heater operation when the coolant is cold. • Demonstrate Manual Air Distribution individual adjustments.