Can I charge my coil even when its charging contacts are dirty? Isn’t there a risk of short-circuits in the water or elsewhere?

[FORUM XP]

The coil’s charging contacts are flush with the upper side of the coil, they have no rough edges and can be cleaned simply by wiping them with your finger. The charging clamp connects easily, due to the raised guides on the coil cover; these are robust enough to accept the clamp even when dirty. Even without the coil cover (and its guides) you can connect the clamp by manually aligning the charging contacts.

The charging contacts are then shielded internally by a protection circuit. In simple terms, the current can go in but cannot come out again. So there is no risk of short circuit when in contact with water or metal.
Nevertheless, you should never tamper with the power supply or try to charge the detector with anything other than the XP charger, as this is very dangerous and could lead to fire or explosion.