Batteries are the heart of RC vehicles, whether they are cars, trucks, planes, or helicopters. A battery failure in the handset means, at best, a vehicle that does not run, and at worst, a vehicle that crashes or gets lost. Battery packs that do not charge close to their rated capacity or those that show temperature extremes during charging are suspects for failure. RC plane controllers should ensure that their cyclers and voltmeters show the necessary figures before flying.
Battery Does Not Charge to 90 Per Cent of Its Rated Capacity
A battery cycler is a critical part of an RC controller's gear, especially for those who fly RC planes. The cycler charges and discharges batteries under a load and gives an accurate measure of the battery's capacity. If the battery no longer reaches 90 per cent of its stated capacity, enough cells in the battery have failed to warrant replacing the RC battery pack. Of course, if the pack has been in storage for a while, it may need several cycles to get back up to the maximum capacity that it handles.
Battery Gets Hot or Stays Cool After Charging
Temperature is a good indication of charge because once cells are fully charged in the charger, they start to give off excess energy as heat. A fully charged battery pack should be warm, not hot. Up to around 5 degrees above the ambient temperature is normal. If the battery pack is hotter after the normal charge time in the charger that you have always used or it does not warm up at all, this may be a warning sign. High heat ruins batteries so be sure to stop charging the batteries if they heat up too much. Also, using a different RC battery charger may cause the battery pack to behave differently; therefore, make sure the charger's settings match the battery manufacturer's recommendations.
ESV Shows Less Than 1.2 Volts per Cell
While RC car controllers can afford to use older and weaker batteries without suffering serious consequences, the results are disastrous with RC plane controllers. An ESV, or Expanded Scale Voltmeter, is a key part of a plane controller's gear, much like a battery cycler. This voltmeter shows the voltage of the pack under a current load when on the field, just before a flight. When the ESV shows a voltage of less than 1.2 volts per cell, the battery pack is neither in peak condition nor reliable enough to use for a flight. These batteries may still be useful for other non-flight tasks however.