The limit of an "ALGE" din connector cable is 30m. We always recommend using the internal battery and the banana plug connector beyond that. The cells will work exactly the same with either power source. Therefore it is a matter of installation requirements as to what you use. If your timing building is within 20-30m of the posts, use the DIN cable, If it is further, use the battery and banana plug.
Properly installed and aligned cells will work reliably regardless.
The din and banana plug sockets are wired together inside the cell.
The battery drain on a set of cells is reasonable. The only way to tell is by using a volt meter and checking them. Fresh batteries installed in the morning should read 1.6 volts. By the end of the day they will be about 1.45 volts.