I have a stepper motor with built-in controller/servo system that requires a supply voltage of 24 VDC +/- 10%. The problem is, the power system I'm using is a lead-acid battery that is normally maintained at a top up voltage of 27 V to 28 V, which exceeds the upper limit motor input. Most of the other 24 V components in my system are fine with inputs ranging anywhere from 18 V to 36 V DC, so this hasn't been an issue before. I want to step down and regulate the battery voltage using a DC-DC converter, but my concern is with reverse current. My preliminary investigations show that some DC-DCs can handle bi-directional current flow, and some can't, but I haven't been able to find any information about which is which (DC-DC data sheets don't seem to explicitly indicate this). Does anyone know what kind of DC-DC power supply is suitable for use with a BLDC (or stepper) motor? This must be solved problem. Thanks, cepheid.