Charging and Maintenance of Batteries for Your RC Toys

by: Jen Chan

It goes without saying that one of the crucial components of RC helicopters – or RC toys for that matter – is their batteries. Battery technology has evolved in the last few years and this ensured longer flying hours and added reliability to RC helicopters. Had the battery technology not evolved, many RC models in our possessions today would have remained ridiculously expensive or inaccessible for the common man. A wide range of battery technologies are available today, ranging from Lithium Polymer (Li-Po), Nickel Cadmium (Ni-Cd) and Nickel Metal Hybrid (Ni-Mh).

It is important to understand each type of battery for RC helicopters, how they function, their charging time and lifespan, so that you can ensure longevity of your RC helicopters. There are many incidents of crashes primarily because of the poor maintenance of RC helicopter batteries. Compared to the price of an RC helicopter, batteries are relatively inexpensive and it is a wise idea to maintain them properly to avoid permanent damage to the more expensive helicopter itself. 

Basic Battery Specifications 

If you are new to RC helicopters, terms such as 7.4V, 2700 mAh etc. can confuse you. What does a 7.4v 1500mAh 2S 30C battery mean to your helicopter? The typical voltage of a Lithium Polymer batter is 3.7volts. So a 2S, 7.4v battery means it has two cells of 3.7volts! If you at least have primary school education, you already know what ‘v’ stands for! ‘v’ stands for volts. However, you can get confused with the Kv ratings on brushless motors in RC helicopters. The ‘Kv’ on RC helicopters doesn’t stand for 1 kilovolt (1,000 volts) as many beginners think. Instead it represents how many RPM (rotations per minute) the motor can do per volt.

mAh – Anyone with a basic understanding of helicopters would have already figured out that the mAh ratings on battery somehow represents power. But what to make out of this rating is an unanswerable question for many. Let’s take the 1500mAh rating on our example: what does it really mean? Thousand milliamps is equal to 1Amp. A 1,500mAh battery can power a 1 amp motor for 1.5 hours. If the motor capacity is 10 amps, the same will fall to 1.5 minutes! If you increase the mAh, you can propel your helicopter to longer durations. Many RC owners push the flying limit of their helicopters with larger battery packs till the power to weight ratio stays within the acceptable category.

The ‘C’ rating – What does the 30C on the battery stand for? C on battery ratings stands for capacity. C rating is used to tell you how fast a battery’s charge can be consumed (discharged). A 1500mAh battery can be discharged at a rate of 45amps or 45,000mAh! 

Understanding Li-Po batteries and their benefits

Lithium Polymer batteries are known to be lightweight in comparison with Nickel Cadmium batteries with a similar capacity. This makes your RC helicopter significantly lighter. A lighter helicopter naturally tends to be faster and cover longer distances. Similarly, the chemical structure of Li-Po batteries results in much lesser internal resistance. In layman’s terms, a lithium polymer battery do not waste energy overheating, which means every drop of charge is used to power your RC helicopter’s turbine. They also offer higher voltage in real life situations, which makes your RC toys faster and energy efficient.

A combination of these properties makes Li-Po batteries the most desirable choice for RC toys owners that prefer power and longevity with each flying session. Moreover, Li-Po batteries can be practically made into any size and shape. In the past, electric flight was not a viable option because of shorter flying durations and underpowered engines. However, LiPo batteries could successfully replace the fuel powered RC heli engines to a large extent by offering equivalent power and being practical alternatives. 

Lithium Polymer Batteries – how to make the most use of them? 

Structure – Li-Po batteries, as the name suggests, uses a Lithium chemical base and is suspended in a polymer matrix (now you know from where the name ‘Li-Po’ came). The average cell voltage of a Li-Po battery is 3.7 volts, the operational voltage ranging between 3.3v and 4.2v.

Safety – Li-Po batteries are proven to be safe and user-friendly under normal operational circumstances but they are not known to take mishandlings really well. If you were to use Li-Po batteries for your RC helicopters, be prepared to be a careful handler of these batteries. 

Why do Lithium Polymer batteries demand extra care from users? 

Lithium Polymer batteries are prone to damage if mishandled. Physical damage to the batteries can cause explosion. Overcharging and complete discharging can also damage these batteries. This is why the batteries need extra care. Once the battery is removed from the storage, it is put under core inspection for any damages like dents, scratches, punctures, swelling, broken cells, heat shrink or distorted wires. After confirming that the battery is under perfect condition, it is connected to an open circuit voltmeter and a lowest pack voltage is out to 3.3 V for every cell. For instance, a pack with 3 cells has 9.9 Volts.

If the battery condition does not meet the required expected perfection, it is disposed off immediately. However for minor damages which can be repaired and retained, repair work will be carried out so that they can continue to be used.

Nickel Cadmium and Nickel Metal Hybrid batteries

Nickel Cadmium and Nickel Metal Hybrid batteries are no longer a favorite among expensive RC helicopters because a few bucks you can save on the battery can have an adverse effect on your RC chopper. For instance, a Ni-Cd battery is heavy and may work well for an RC car as the power to weight ratio is not as significant as an RC helicopter. If you have cheap chopper models and you are still on the learning phase, these batteries make sense but for advanced users, Li-Po is the way to go. 

Basic Care for your batteries 

  • Always store your battery in the suggested temperature levels. Nickel Metal Hybrid batteries have poor low temperature performance. Move them to warmer enclosures in winters.

  • Li-Po batteries are prone to damage if overcharged or drained out completely. Use a charger with the cut out system to make sure that they are never overcharged. Do not push the limit of your helicopter that will eat up the whole battery power when using Li-Po.

  • Nickel Cadmium batteries require occasional full discharges in order to maintain their longevity.

  • Do not fly your RC helicopter with damaged batteries, especially in the case of Li-Po. Explosion is just one possible danger in using damaged batteries but Nickel Cadmium batteries, if not maintained properly, can ‘die’ unexpectedly. This means your helicopter may crash unexpectedly.

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