Ok, all my battery powered devices seem to be working now for a couple of days, so I want to give a short summary for anyone reading this thread. Everything here is explained more or less in the documentation of z-wave binding, but I always have to learn the hard way it seems.
First mayor insight: when adding a battery powered z-wave device as thing from your inbox you are not done! You can then link channels and configure everything, but the device needs to run through several steps of an initialization phase first before they become usable (visible for example in HABmin when it says Node initializing: REQUEST_NIF). The communication between the controller and the device can only happen when the device is awake, which in the case of battery powered devices may be only one time a day for a few seconds. So you could wait, but that may take many days or even weeks. On every z-wave device there is a button (or something similar) to wake it up though. This you can do (Ihad to triple click the button, like for the initial inclusion), and have to do it many times until the initialization is complete. It does not necessarily take the same amount of tries, even if the devices are identical. You can watch the log in debug mode or simply repeat the waking up of the device until one of the linked channels actually gets values (I used the battery status).
In one of my devices it did not go forward even after waking it up for many times (I guess 50 times at least). What I did is soft reset the controller.
After that I only had to wake the device up a couple of times more and it was done.
Even though one strength of the z-wave network is the mesh, for this initialization you need to be in direct range of the controller. Once that is complete you can move the device to the final location, even if communication has to go through other nodes to the controller. I don’t know if the first inclusion needs to be already in the final location so that the device knows where in the mesh it is located. I did this though, and had no problems afterwards.