Hmm, 100W means 4A at nominal load, bit too powerful for most Arduino shields I think - you need to measure the winding resistance to calculate the max current at stall (that could be up to 50A!!), then you'll need a decently capable MOSFET H-bridge motor controller that can handle those peak currents.
Also if you are running from 24V batteries select a 30V or higher controller, not 24V as charging batteries brings them up to 28V easily...
ok I'm following you for most of it. With the other beefier controller that you brought up, do those just control a single motor? I'm trying to make something that can use differential steering to drive. Any ideas?
You'll have to look around, there will be dual motor controllers too I'm sure - single controllers are more common. Did you measure the stall-current (ie winding resistance) of your motor then? Or locate a datasheet?