When I first posted the moteus controller up for sale, the specifications I listed were based on the design characteristics and the testing I had conducted up until that point. Specifically, the peak phase current was just the maximum that I had verified was safe to operate with.

In the interim, I’ve done a fair amount more testing and have concluded that the controller can safely drive higher phase currents than initially posted. For now, I’m increasing the peak phase current to 100A both on the specification sheet and in the default firmware configuration of all newly shipped boards. If you already have a moteus controller and want to take advantage of the higher phase current, chat us up on the mjbots discord and we’ll show you how.

When I first posted the qdd100 beta on mjbots.com, I performed a simple “continuous torque” test where I measured the torque that could be applied indefinitely without thermal limiting in a lab environment. It has come to my attention that other servos rate their “continuous torque” for a much lower value of “continuous”, sometimes only 30s. To make the situation clearer, I measured the time to thermal limiting at a range of torques and updated the product page.

When I was trying my first pronking, I kept having over-voltage issues when the servos were trying to dump power back onto the DC bus, no matter how high I set the voltage limit.  During that test, I was running with a nearly full battery, so my working theory is that the battery protection circuit was disconnecting the battery either because of too high a charging current, or too high a system voltage.  When the battery was disconnected, and the servos were still putting power onto the bus, that resulted in the voltage spiking arbitrarily high, followed by a total loss of power when they all faulted and then nothing was powering the bus at all.