I had a project at work that was going to use a Futaba 2.4 system per the customers request. I contacted Futaba about runing A123's without a regulator into their receivers, and was told not to, that a regulator should be used, but a 5 cell nicad was ok. Maybe it has to do with the steady 6.6 volts?

Horizon was ok with a A123 pack with their recievers. So we used a regulator for the project using the Futaba equipement with no issues.

I have no issues with either equipment, I just do what the manufacturer suggest.

I did notice that the DS 168 servos show they are rated at 6.0 volts.

Clay