Hi there!
Just in case this is not already a known issue: It appears that the Remote Thermal Monitor does not get any more EU energy after the chunk it resides in has been unloaded/loaded. Although i first noticed this on a multiplayer server, I am able to reliably reproduce this problem in single player: Place the monitor next to the output of a filled BatBox. The monitor's energy bar fills up and stays at 100%. Then teleport to distant coordinates so that the monitor's chunk will be unloaded. After teleporting back to the monitor, its energy bar diminishes until empty and stays empty, even when reconnected or removed/placed again.
This appears to happen with both current versions: Version 2.1.2a and Version 2.2.0a-Yolo. The IC2 version I'm using is industrialcraft-2-2.2.688-experimental, MC is 1.7.10.
I'm using a heavily modded client, so I don't rule out that the problem might be caused by mod interference or by using an incompatible IC2 version (?).
Cheers,
Gwani