Hi Bax, I do not see a 6.0V voltage rating for the S3151 servo. Does that mean that they are restricted to four cell battery packs and nothing higher? Thanks, Dan.
Futaba only has specs for a 4.8V 4-cell NiCd or NiMH battery pack. Do not use a 2S lithium battery pack. The servo was designed in 2002, long before higher-voltage battery packs became common.