I just completed a "running test" of my latest robot frame ( just letting it run in a circle to see how long the battery lasts, how hot motors get, etc ), with the motors connected straight to the battery.
Would using a speed controller, in general, sacrifice any battery time as a trade-off in controlling the speed ? For example, if I rigged up the speed controller to run full speed (like I have it now) should I expect about the same amount of run time or less ? What about half speed? When I ask this, I am talking about using controllers such as the Devantech MD03, MD22, or the L298 Dual H-Bridge kit from Solarbotics.
I am running 2 12vdc vending machine type gearmotors + small caster on an 8 lb frame, lawnmower wheels, level hardwood floor, from one 12vdc 5Ah SLA battery. I was quite surprised that it ran for over 25 minutes with the motors barely generating any heat! Seems like it could easily go another 25 minutes! So when I add in the controllers should I expect any performance changes. I plan on using a separate battery for the logic/motherboard, etc.