All batteries have a capacity or rating. The capacity can tell you how much power the battery can supply in a period of time, or how long the charge will last while powering your system, appliance.

Battery capacity for our purposes is usually stated as mAh, and ampere-hours are used for larger-capacity cells. Most remote control systems through the years have been powered by Ni-Cd rechargeable batteries of approximately 600 mAh capacity. Thanks to the newer NiMH technology, higher-capacity cells are being offered with some systems.

For most purposes, the Ni-Cd cell’s nominal voltage is 1.2 volts. If you applied a load of 600 milliamps to a fully charged Ni-Cd cell, it should take exactly one hour for that cell to reach 1.0 volt. At that 1.0-volt level, the cell, by definition, would be considered discharged. If you continued to load the cell, the voltage would rapidly head for 0.0.

We usually see remote control transmitters with eight-cell battery packs. Using the nominal-voltage rule, eight of these cells in series would produce a total of 9.6 volts. If we used a commercially available lifepo4 battery tester, we would apply a load until that pack reached 8.0 volts, at which point the testing device would cut off and the capacity in mAh could be read off of a monitor, meter, or Liquid Crystal Display screen.

Regularly discharge testing or cycling your battery packs would eliminate the problem if it actually ever existed. Remote control system batteries tend to be used at roughly the same rate, so periodic testing cycling can’t hurt in that regard.

Nimh batteries used for electric-powered flight are usually taken down to the minimum charge level on each flight. As such, they are essentially cycled on every flight. It would be difficult to conclude that batteries used in this manner require additional cycling in your shop. When your electric-powered model refuses to take off or support flight, then you know you have a battery problem and can investigate further. But don’t bother to cycle these batteries. It’s unnecessary.