I want to control a Rule brand 3700 gallon per hour bilge pump on a yacht with an Arduino. The pump pulls a continuous 15.5A at 12V under load. The User Manual for the “Arduino Compatible Mega Motor Shield 13A, 5-28V” sold by the Robot Shop shows the two controllers (13A each) can be ganged. There is a table that seems to show that the current handling for the entire shield is doubled to 26A if one motor is ganged across the two controllers. Is that actually the case? I don’t want to order the shield if it can’t handle the current for the pump.
You can indeed combine both H-bridge outputs on that controller and get the current you need for your application.
As explained on page 7 of the manual, only half of the current will be monitored:
robotshop.com/content/PDF/user-manual-megamoto.pdf