I know this topic has been covered before but here's another twist to the story: When powered down the current draw on the battery is about 42uA - which closely matches the 50uA specified in the documentation. However, when power is applied the draw goes up to 5mA draining the battery in a matter of a few days.
I went through all the procedures found on related bulletin boards or FAQs to lower the current draw and tried brand new RCMs to no avail.
As expected, the current draw from the battery is 0A without the controller installed.
Thanks for any hints or ideas!