With this module you may operate 12 V/DC devices at a 24 V/DC truck or marine engine battery. 
Several modules may be connected in parallel if the power shall be increased, e.g. 2 modules do 2,2 A.

Technical Data

Input voltage  24 – 30 V/DC
Output voltage . 13.8 V/DC (for 12 V/DC devices)
Loading capacity cont. 0,5 A, max. 1.1 A (3 min. 5 % duty cycle)
Temperature range app. -15°C – +50°C
Serval modules may be connected in parallel to inrease the power.
Dimensions approx. 60 x 45 x 20 mm (without fixing straps.