Hi,

A thermal fuse is slow. The current peek will be very high before
the thermal fuse triggers. (Lead Battery short-circuit current > 100A).

Poor-man's solution:

In addidion to the thermal fuse, put a 0.47 Ohm/5W wirewound resistor
in series to the thermal fuse. (RadioShack Catalog part #: 271-130).

The resistor will limit the short-circuit current to:
14V / 0.47 Ohm = 29.78 A

Drawback: The resistor will dissipate about 2 watts of power during
normal operation of the motor. (Motor current 2A).

Best regards,

Luciano