Flight Batteries

by Kurt Gornek
 

Overview

Rechargeable batteries have become part of our everyday lives. Our cell phones, laptops, cameras, PDAs and even home telephones all share some of the same battery technology that makes electric flight not only possible, but also a viable alternative to glow or gas engines. Some common types of rechargeable batteries are as follows:

  • pb (SLA/Lead Acid)
  • Nickel Cadmium (NiCD or NiCad)
  • Nickel-Metal Hydride (NiMH)
  • Lithium-ion (Li-ion)
  • Lithium-ion Polymer (Li-Pol, PLI, LiP, LIP, LiPo, Li-poly)
  • Lithium-iron Phosphate (LiFe/LiFePO4)

In electric RC flight, any battery with a high discharge current and high capacity is a viable solution. Other factors such as weight, charging time, lifespan (calendar and life-cycle) and cost are secondary drivers that determine the mainstay battery of the industry.

As interest in electric RC flight grew in the 80’s, the industry relied on rechargeable power sources
such as Nickel Cadmium (NiCad). Gas or glow planes often used off-the-shelf non-rechargeable alkaline batteries for the radio but soon began using rechargeable Ni-Cads as well. The fact was, there weren’t a lot of options in those days. Electric motors were less efficient, less powerful, flight durations were very short due to smaller capacity cells and the batteries were heavy so many gas and nitro flyers didn’t consider it a realistic option to convert to electric.

With improvements in both battery and motor technology, flight times have more than tripled. The batteries are much lighter with more storage capacity and the electric motors can actually outperform their nitro-based counterparts so in just the last few years, electric flight has moved to the forefront in .40-sized aircraft or smaller. Electric giant-scale is a possibility as well with Lithium packs that can offer 150 Amps at 50 volts direct current (VDC). Cost however is still prohibitive for most large/giant scale hobbyists that want to convert to electric. A single engine electric large-scale setup quickly moves past the $1K mark. Having over 3/4ths of the cost of a few thousand dollar airplane wrapped up in just your electric powerplant is not uncommon so large and giant gas or nitro is still a much more affordable electric.

4 Responses to Flight Batteries

  1. avatar pcerne says:

    Returning to model airplanes, I am learning how the sport has evolved to mostly electric. What flexibility does one have to use one battery with more than one model? Can a person use a pack either smaller or larger than what is recommended? I guess the same question applies to the electric motor?
    I find your website to be very informative and thanks for what you do.

    • avatar Kurt Gornek says:

      Battery capacity (mAh) can always be increased assuming the airframe can accommodate the increased physical battery size and additional weight. As far as cell count, that’s a different story. The general rule of thumb is that you stick with the manufacturer’s recommended cell count (voltage) unless you do some research to verify that the ESC and motor can handle higher voltages. The motors can be changed but you’ll need to be sure that the stock ESC can handle the new motor’s amperage and voltage requirements. We have calculators in the tools section to help you re-size your powerplant and even calculate the anticipated run-times. http://2bfly.com/tools/ Hope this helps!

  2. avatar wheels says:

    OK, I have never been proficient at electrical conversions since high school.
    I have a Sensei with the standard battery (11.1v 2100mAh 20 C23 Wh LI Po battery and just bought a Calypso glider which calls for a smaller battery. Will the Sensei battery be OK after making sure the Center of Gravity (balance) is done right?

    • avatar Kurt Gornek says:

      hehe, no problem. You are correct, the only critical factor is the pack voltage of 11.1V DC. Both the Calypso and the Sensei operate on 11.1V DC so you won’t damage anything. The 2200mAh pack in the Calypso will just give you longer run times than the stock recommended 1800mAh pack. The slight increase in weight is not a problem. Just be sure to adjust and re-check the CG as you had mentioned and you’ll be perfectly fine. Good Luck!

Leave a Reply