Well, 4 Stalkers are out there and now the first one drained its batteries.
This gives zoomable graphs and reduces load on the server (and the network).
As you see below, a sampling rate of 0.28mHz (1h :) gives exactly 4weeks of runtime (with the currently unoptimized system!).
I need to say, that I use a ZTE "router" stick.. so there's that 2nd linux running on that stick that makes the UsbLog think it has a USB-ethernet device connected... That draws roughtly the same current as the RPi!
This will definitly change, but was the fastest way to get it ready for the first tests.