I'm very enthusiastic about electric flight and I don't want people put off by their expensive LiPo cells only lasting a short number of cycles. I would like people to enjoy electric flight and continue to enjoy electric flight and here are my recommendations on how to get the most from your LiPo (Lithium Polymer) batteries. Lithium Polymer cells are often referred to as LiPo’s or Li-Poly’s and are a great advancement to increasing the performance and duration of electric flight. If used incorrectly LiPo cells will only give a short number of cycles and in the worst cases can result in a fire. Good quality cells like ours, although cost more initially will easily out perform (hold a higher voltage under load) and outlast the cheaper cells and therefore cost you less in the long term. Good quality cells are also safer in operation then the cheaper far east cells. As with all things in life, you get what you pay for.
Of all the innovation that paved the way to the rise of electric RC flying, battery technology plays one of the biggest roles. Today, modern batteries have a much better power to weight ratio than before. This allows RC airplanes and helicopters to stay in the air for a lengthy period of time - even as long as their nitro counter parts, or even longer. Amongst the types of batteries, Li-Po or Lithium Polymer rates as the best your money can buy. While they cost much less than they used to, it is always wise to make sure that your Li-Po battery will last for as long as it could. This article will provide some pointers as to how to store your Li-Po battery for long periods without sacrificing its overall lifetime.
To get decent flight times (6-10 Minutes) aim to take 15C from your LiPo's at full throttle. Example if using a 3S 2,200mAh pack aim for 33A or less at full throttle (2.2Ah x 15C = 33A).
Gens ace 2s lipo 2,200mAh. Max continuous rating = 40C and a peak of 60C.
Charge as a 3S pack (11.1V nominal) and at 1,760mA (1.7A or 1.8A). (2,200mAh x 0.8 = 1,760mA).
Maximum discharge current is 40C. C is the cells capacity therefore 40C = 40 x 2,200 = 88,000mA which is also equal to 88 Amps.
In this example you should try to achieve the following:
Keep your current draw below 52.8 Amps.
40 x 2,200mA = 88,000mA 88,000mA x 0.60 = 52,800mA = 52.8A
4S lipo batteries 3,700mAh. Max continuous rating = 40C and a peak of 60C.
Charge as a 3S pack (11.1V nominal) and at 2,960mA (2.9A or 3.0A) (3,700mAh x 0.8 = 2,960mA).
Maximum discharge current is 40C. C is the cells capacity therefore 40C = 40 x 3,700 = 148,000mA which is also equal to 148.00 Amps.
In this example you should try to achieve the following:-
Keep your current draw below 88.8 Amps.
40 x 3,700mA = 148,000mA 148,000mA x 0.60 = 88,800mA = 88.8A
If the Li-Po battery is brand new and you decide to keep it for a while before putting it to first use, contrary to common sense, it is best not to store the battery in its uncharged state. The best practice is to fully charge it and maintain it at 4.2 V per cell before storing the battery away for a long time. For example, if you bought a 3 cell Li-Po battery rated at 11.1 V, when fully charged, the battery will hold 12.6 V. This will make it suitable to keep stored away for 3 to 6 months. However, after 6 months, the voltage will start to weaken. When this happens, fully charge it again, whereby giving another 6 months of storage time. While this procedure can be performed over and over, the battery shouldn't be kept without being used for more than 2 years.
7 More Tips to Get The Most From Your Battery Pack
• Don’t cut corners. Buy the best battery pack you can afford it pays dividends in the long run.
• Chargers that come bundled with many models are marginal at best, upgrade to a better charger whenever possible.
• Get a charger that has a built-in voltmeter or pick up a multi-meter separately so you can easily monitor the condition of your batteries.
• Avoid charging your batteries after each flight if they are still hot to the touch.
• When planning to store your batteries for a long extended period of time, avoid storing them with a full charge. Instead discharge them after a normal flight and store them with only small charge on the battery.
• LiPo battery packs do not have a “memory” so there is no need to cycle the batteries like traditional NiCad battery packs. In fact, cycling your battery pack will actually reduce the batteries performance.
• Avoid overcharging. Overcharging a battery will reduce the batteries ability to hold a charge.
Taking care of your batteries will save you in the long run. You will save money, in terms of extended battery life, but also, you will save yourself from increased risk of damage to property, equipment, and human life. Drones and remote control aircraft are a fun and rewarding hobby, but proper precautions are essential to keep yourself and those around you safe.