Discharger
May 23, 2005, 11:21 PM
Recently there has been some discussion on this and another board regarding using a 2S li-po battery instead of the common Ni-Cd or N-mH for the on board flight power supply. The main concern seems to be the voltage from the li-po can be from 8.4v off the charger to around 7v and to most this is regarded as a tad too high for a system that normally takes 4.8v - 6v. In the midst of cries of burning servos and hemorrhaging receivers, one writer reports that he has been using the full whack from a 2S li-po directly to his various aircraft systems and no problems were encountered after many flights and in fact the increased servo speeds and responses were welcomed. Certainly it would seem most Rx's are rated for higher supply voltages (Schultze Alpha 9v) so these should not be a problem. But what of the servos long term? Until the manufacturers re-rate their products I would be a bit hesitant to use the higher direct voltage so I tried an experiment on the bench with a JR R700 Rx coupled to 4 NES507 servos and 2 1N4001 diodes in series to drop the voltage by about 1.4v. The servos were loaded up with elastic bands to simulate flight conditions and the Tx sticks given a good jiggling. All seemed to operate normally and after a few minutes a check made on the diode temperatures. These were only just warm to the touch indicating that this could be a suitably simple and effective solution to using a 2S li-po for a flight pack. An electrolytic capacitor from - to + after the diodes could be to advantage.