batteries
 

what is the difference between ni-mh and ni-cd? do any have dissadvantages? advantages? can any of them not be used with FM, HRS, and digital servos?

RE: batteries
 

NiCd and NiMh refer to the chemical composition of the battery. NiCd batteries are made with nickel and cadmium, NiMh batteries are made with nickel and metal-hydride. NiCd batteries run strong all the way to depletion, and then their power drops off quickly. NiMh batteries tend to run strong and then "taper" off when depleted. NiMh is a more current chemistry and seem to hold a charge longer and they are lighter than NiCd's for the similar power. Basically, NiCd and NiMh batteries can be used interchangeably with NiMh being usually preferred due to weight, power, and the fact that they have no "charge memory" as the NiCd's do. The subjects are only briefly discussed above and I encourage you to research further for a more thorough understanding of the differences that are significant to us in this hobby, but suffice it to say, either battery can be used interchangeably in all of our electronics.

Aeromite

RE: batteries
 

NiMh somewhat lighter for equivlent capacity in mah.
NiCad more robust, i.e. less easily damaged due to abuse.
NiMh have twice as high a self discharge rate as NiMh.
NiMh has about half the life span of NiCads, roughly 500 charge/discharge cycles for NiMh and 1000 for NiCad.
NiCad have slightly lower internal impedance so more efficient than NiMh for high current applications.
The only real advantages of NiMh over NiCad are lower weight for equivalent capacity and, after their life is over, NiMh is less damaging to the environment after disposal. By the way, the way we use NiCads, memory is not a problem and never has been.