BMW Battery drain issues or error messages in dash about battery voltage

This article applies to the following BMW products and serial numbers:

STE93 ALL modules WITH USB port

STLFBW1 serial numbers 090501-001 up to 100701-025

RKLFBW1 serial numbers 090501-001 up to 100701-025

TVLBBW1 serial numbers 090501-001 up to 100701-025

NEWER MODULES and STLFBW3, STLFBW4, STLFBW5 etc. are NOT affected!

Problem:
In some instances we have gotten reports of drained batteries, touch door handles not working the next morning or battery warning messages on the dash cluster. In rare cases the car wouldn't start or the remote appreared to be dead the the door had to be unlocked mechanically with the key.

Cause:
The modules above are susceptible to a problem that occurs when installed in a newer model BMW with switched power supply. Especially 6 Series and 3 Series with Comfort Access (keyless entry and keyless engine start/stop) seem to be affected. These cars turn off the power supply to most of the control modules when the car has been idle for more than 15 minutes. This measure is designed to prevent a drained battery when the car is sitting for prolonged periods of time. Unfortunately this conflicts with the standby power saving mechanism of these described modules! Our modules have a sophisticated self-power-down standby mode in which the processor in the module is turned off, but immediately wakes up when any data traffic is detected on the data bus. The module itself consumes only very minimal power in this mode. It is mandatory that the module is permanently powered. Otherwise, on cars with keyless access where the circuit with radio and top control unit is NOT powered up upon touching the door handle or trunk button, the module is left unpowered and unable to receive or transmit any data.
Our module, much like a network router, receives and transmits data packets on the car's data bus. If the power is interrupted, no communication across the module is possible, data is blocked! This leads to other control modules permanently trying to communicate and thereby draining the battery.

Solution:
If you think you are affected by this problem, PLEASE CONTACT US in order for us to verify this and offer you a solution.