15 lb. plane

[alanh]

I want to buy a G26 brushless motor from Motion RC which requires a12S(2x6S in series) Lipos. They then recommend a 120 AMP ESC a Gecko 120 AMP which also needs a 10AMP BEC. But the Bec only can be powered by a 6S-25.5 volt Lipo!!. So which Lipo do I get--a 6S will not provide the suggested voltage for that G26 motor. I am removing my DLE 30cc to go electric. Has anybody done this before.

[Mezri]

At that point , you can put a 2S lipo 2000 for the BEC and let the power drive isolated...if you get trouble with short, lowpower, full drain...your servo system will still function and still having control...with 6S, your BEC will need to dissipate more heat...the 2000-2S lipo is enought for the day...os put 5-elements-NiMh, LSD (low self discharge) for receiver and servos, they last years and keep 80% of their charge even after 6 mounths, you will forget about the old non reliable NiCd, NiMh...dont buy them from hobby stores, they still have the old generations....

[mdauth]

Hi Alan, what Mezri said is good however if you don't want the extra battery I use a CC BEC Pro works on 12s. This set up was done a good few years ago on my 30cc electric so I'm sure you can find equivalent items on the market.


https://www.castlecreations.com/en/cc-bec-pro-010-0004-01

[alanh]

Thanks guys---yes there seem to be a variety of ways to power your receiver when using electric motors. Most ESCs have an internal BEC(voltage regulator) to power the receiver and servos but if the ESC ever fails you will crash your plane. On a larger plane its a major safety issue if that happens. So its a good idea to have a separate power source supplying voltage to your receiver. Using an NIMH or LION battery is one option but using a UBEC or separate voltage regulator is another option. If the ESC fries you will still have power to the receiver thru your Lipo. I noticed later that Motion RC offers an 18 Amp UBEC that can be powered up t0 60 volts so that may work and that Castle voltage regulator at $39.95 US looks interesting as well. What was mentioned about defective NIMH batteries is also a worry. I bought all mine from Hobbyking and once before taking off I was checking all the control surfaces and everything went dead on a fully charged NIMH!! The wire from the battery shorted out and I had no power. I may just use 2 x 6 volt NIMH batteries connected in parallel(y-connector) going thru 2 switches for redundancy although the extra weight is an issue.

[Ricardo]

For larger airplanes I would go for redundancy. No single connector or power supply should lead to loss of control.
I suggest one nimh battery pack plus one bec. The bec coud be connected to the first of the 2 6S you have in series, or to a dedicated 2S as suggested by Mezri.
In my setups I have the Bec output connected to the receiver via a schotky diode, and the nimh also connected to the RX via a different connector.

[alanh]

What does the Schottky diode do.

[Ricardo]

It avoids that the batt voltage goes into the bec. They must be both the same voltage, example a 6v bec and a 5 cell nimh.

[Jdonald]

Horizon Hobby Spektrum Avian Smart 120 amp Cont. Current ESC has a 10 amp BEC with 2 Leads from the BEC. 1 lead for throttle and the other can be inserted into the bind plug or any other open port on the receiver. It is also has 2 battery input plugs so no series Y connector is required to use two 6s Li-pos.The plugs are IC5 [EC5 compatible]. The IC5's can be removed and male XT90 installed and female XT90 with a built in resistor installed on the battery's. Or short adapters can be made. Two 6s lipos in series have about 50 volts and give a nasty spark when connected to the ESC, the arc makes short life of the connectors and possibly the Li-po. The use of the XT90 resistor is tip from Mezri.
This 120 amp ESC comes with a cooling fan.