Hey, I recognize that motor image in your ad!
You can test a big DC motor just fine with a fully charged 12v battery. Jump it off your car battery, if you like.
The motor in the ForkenSwift, unloaded, will turn at no more than about 1200 RPM on 12v. Too much voltage and you risk getting into a runaway situation (DC motors will do that under no load) and could wreck it.
Here are some things you should look for (you may have to remove the brush service covers to see this stuff):
- ideally, you want an 8 brush motor (4 brush pairs)
- the brush leads (thick copper strand braided/twisted wire, usually) should be coppery, not dark red/purple or brown/black (indicating overloading/stalling)
- an internal shaft driven fan on one end is useful, but not strictly necessary (you can add external cooling)
- the bearings should spin freely & quietly
- the commutator surface (which the brushes contact) should be smooth, not scored. It should be a shiny, coppery or deep brown in colour (not blackened)
I'm probably forgetting something. But those are 5 or 6 tips I wish we'd had when we were out motor shopping. All we brought was a tape measure
... and a lucky rabbit's foot.