Originally Posted by abenn
Neither of the servos you mention are rated for over 6.0v. Since you say the JR servo was not connected to anything when it fried, I guess you've demonstrated their voltage limitation.
Reversed servo connection shouldn't have caused any damage, but the servo would not work at all when reverse-connected because it wouldn't be getting any signal from the receiver.
Do you not think that the servo manufactures do not know what nominal voltage and charged voltage of a 6.0v battery is? Both servos give a spec for 6.0v. If it wasn't rated for 6.0 volt they wouldn't have specs for it. A 5 cell nimh/nicad go over 7 volts when fully charged. A123's do the same thing. People have been doing this for years.
ds821=Speed: .19 sec/60° @ 4.8v .15 sec/60° @ 6v ,Torque: 72 oz-in @ 4.8v 88 oz-in @6v
Futaba 3152 = Speed: .22 sec/60° @ 4.8V.,,18 sec/60° @ 6V Torque: 70 oz-in @ 4.8V , 87 oz-in @ 6V
I would look for a crossed up wire somewhere.