Radios and other electronic devices must be battery-powered. What sort of battery - and does its capacity impose a limit on flight duration, or can they be recharged in flight with a turbine?


1 Answer 1


Gliders generally use "Gel Cell" or Sealed Lead Acid rechargeable batteries, a little bigger than a block of butter, that will run designed-for-glider low wattage radios, and sometimes transponders, and FLARM systems (a kind of TCAS) and various other gadgets, and are good for several hours of operation (the total current draw of all the services might be under 1A when not transmitting on the radio, so a 5 AmpH Gel Cell 12v battery might be plenty unless you are talking all the time). Enough for normal glider flights and tasks, and if necessary you can hook up a second one if expect to be out for more than 4-5 hours.

Some newer batteries of the more exotic Lithium chemistry are starting to come on the scene, but the thing is the gel cells are light enough and are effective and trouble free, and don't require an STC (Supplemental Type Certificate; basically a 3rd party field modification), so the switch away from gel cells will be slow.

Recharging in flight with a turbine would be a real L/D killer so it's out of the question. Much better just to install provision for a second battery for long flights.

  • $\begingroup$ Nice answer. I've also seen small solar panels on the glareshield or turtleback. They help the lead-acid battery last longer in flight and save the hassle of removing it from the aircraft to recharge between flights. $\endgroup$ Jun 18, 2019 at 3:54
  • $\begingroup$ Thanks. Can you expand "STC"? $\endgroup$ Jun 18, 2019 at 7:22
  • $\begingroup$ Block of butter can come in various sizes. Can you use a better example? $\endgroup$
    – Steve
    Jun 20, 2019 at 21:27
  • $\begingroup$ Say, roughly, 3" wide, 6" long, 5" high. Something you can hold in your hand like a brick. At least the ones in my club's gliders. $\endgroup$
    – John K
    Jun 20, 2019 at 21:35
  • $\begingroup$ Simplified: STC = supplementära type certificate. Any change done to the design of an aircraft has to have paper work. The STC is the paper work allowing you to do specific changes, say changing the type of batteries to a type not originals part of the plans. The STC has to be created by someone and approved by the relevant authorities (ie casting time and money). $\endgroup$
    – ghellquist
    May 6, 2020 at 20:17

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