This is essentially a ramped up version of our Ardumoto motor driver shield.
For this monster shield we've replaced the L298 H-bridge with a pair of VNH2SP30 full-bridge motor drivers.
We've also beefed up the support circuitry so this board is capable of driving a pair of high-current motors!
The VIN and motor out are pitched for our 5mm screw terminals (not included), making it easy to connect larger gauge wires.

Note: When using this board in extreme high-demand applications it may be necessary to improve thermal performance with a heat-sink or fan and to solder the wires directly to the board instead of using a screw terminal (in addition to the myriad other complications present in a high-current system) However, when using the board at currents up to 6A the chips will barely become noticeably warm.

Features:

• Voltage max: 16V
• Maximum current rating: 30 A
• Practical Continuous Current: 14 A
• Current sensing available to Arduino analog pin
• MOSFET on-resistance: 19 mΩ (per leg)
• Maximum PWM frequency: 20 kHz
• Thermal Shutdown
• Undervoltage and Overvoltage shutdown

Documents:

• Schematic
• Eagle Files
• Datasheet (VNH2SP30)
• Example Code