I used this motor controller at regionals yesterday without fully testing out the robot at first, and I must disagree with WSM's praise for the device. Its cost, while quite low for its featureset ($125 + shipping), is still quite high and is not justified by its ability.A 2 channel 25 amp speed controller from Dimension Engineering that I choose for its regenerative braking and built in current protection and protection for Lipo's http://www.dimensionengineering.com/Sabertooth2X25.htm
- Its lithium protection mode is far too overzealous, cutting back power at around 3.2 to 3.1 volts per cell, which caused problems with my LiFePO4 batteries, which are nominally 3.3V per cell, despite the fact that the datasheet states a 3.0V cut-off. Accelerating too quickly would result in enough of a drop in battery voltage that the controller would simply switch off.
- Its servo pulse input mode, especially with the RC radio auto-centering and auto-ranging, is far too flakey. When operating under normal, stable conditions, the controller would randomly become uncalibrated, reverse directions, or often even reset.
- While its current capacity is very high, it refuses to operate at its stated peak and sustained current ratings. It simply decides to cut off, though I was using it on only two 550-size motors, geared down 51:1, driving a 5 pound device. It would often lock up as I accelerated (even with the lithium protection off), even though I know for a fact that the robot's current draw is under 5 amps as it drives and that its peak current (when accelerating) doesn't come close to the 50A peak stated in the data sheet.
I replaced the motor controller with Dimension Engineering's second in line model, the 2 channel 10A controller, and it now functions perfectly, unless I bump the control stick from 0% to 100% instantaneously. I simply cannot understand how a nearly identical model of the controller, with worse specs, is so much better than the top of the line model made by the same company.
Basically, don't get the 2x25A controller. The 2x10 is fantastic, and is a better deal than the 2x5.