ORIGINAL: VF84sluggo
What I care about is whether or not the A123's or 5-cell NiMh's are going to cause my R6014HS or 9252 servos to fail.
Well, I can tell you that I am running unregulated LiFePO4 packs (6.6 volts) right now even with servos (S3150) not rated for 6 volts with not one single issue. Beyond that, I have run nothing BUT 5-cell NiMH for the last several years, again with no issues. I have a large number of 9252 servos that I have run on 5-cell NiMH, again no problems.
I have no idea why Futaba is so conservative with their recommendations, but they are. I also know based on my personal experience and that of numerous others that 5-cell NiMH pose no issues at all. I am also establishing a clear track record on the success use of LiFePO4 packs.