Mirar lo que me acabo de encontrar, es una especie de alternador como en los coches, que nos sirve para mantener la carga de las baterias que alimentan al receptor:
Specifications:
Weight: 3.7oz as seen not including mount
RPMs: 4000 to 18000
Output: 5 volts at idle, 12 to 18 volts in flight (unregulated).
Motor Capability: About 70 watts
Rectifier: Up to 10amps at 25 volts.
Regulator: 5.4v out, 3 amps continuous, 5 amps for 5 minutes.
Charging current decreases to 0 amps when battery reaches 5.4v.
Can be modified to supply additional output of 11.3v for AP rigs.
Axi Motor, shaft couplers, AC to DC converter, regulator, universal output lead to receiver. $200 for what you see here plus shipping and paypal fees if applicable.
Options:
1) Remote charge indicator LED: $10.
2) Custom mount for specific platforms: $20 - $55.
3) Bench power-up plug (use external power source): $10.
4) Voltmagic battery monitor with Peak Low Voltage detection/Glitch Monitor, $40.
Mas info:
http://mysite.verizon.net/vze49gsg/ 
Aqui lo podeis ver acoplado en un T-REX 600 Nitro (Fuente:
http://www.runryder.com)
RC Hobby Generator mounted on Xcell Gas helicopter 3 amps continuous output at 5.4 volt, 5 amps burst for 5 minutes. Use with 4-cell NiCD battery 1000mah to 1700mah capacity as a backup power supply and generator will keep it charged as you fly.
Generator outputs 12 to 18 volts as seen to the right depending on engine rpms. C-Volt not included and was only mounted and used as a verification of power output during initial tests. During this test, the helicopter was actually flown for 15 minutes doing 3D WITHOUT A BATTERY (not intentionally and only on generator power) so this system is PROVEN to work!
Will fit model helicopters such as the Xcell 1005 shown here, the Xcell Spectra-G, the Predator Gas, the Bergen Intrepid/Observer, and the Vario Acrobatic. Mounts include all necessary hardware. Pricing as follows: Xcell 1005, $45, Spectra-g, $55, Predator Gas, $40, Bergen Intrepid/Observer, $25, Vario Benzin/Acrobatic and ASI Mongoose, $40.
C-Volt showing RX battery voltage hovering just over 5 volts under rx/servo load after rest. C-Volt shows 5.3 volt in flight under load. Green LED is my latest addition and is a charge indicator. Lights up only when engine is running to show that generator is working. Can be added to your system upon request.
Minair 1005 gasser mount. Custom cut out of carbon by Minair and comes complete with all hardware necessary to mount generator. For $45, you get a professional mount that will reduce your generator install time from a night to less than an hour.
Dilber MC Theme by HarzeM modified by Madcortina