jersue

My Feedback: (40)

I know this subject has been debated before and that most people think it is bad idea to run a BEC in parallel with a separate receiver battery pack without disconnecting the red wire, but I am looking for the reasons "not" to do it. The BEC puts out approximately 5 volts, the same as a 4 cell NIMH battery pack, so why not run them together. To me it looks like the same thing as hooking two 4 cell receiver packs together. I have heard that a BEC and battery pack hooked together will fry your receiver, and I discount that outright. It seems to me that this is great idea. It provides a redundant battery supply, and your primary flight battery keeps your pack fully charged while you fly. Right now I am flying a 4 engine B-17 with all ESC's hooked together into one lead (red wire still connected) and also a twin engine Mohawk with both ESC's together (red wire still connected) and have well over 100 flight with "zero" problems. Some people think that connecting them in parallel may cause the ESC to overheat, but I don't understand how that can be as long as both power inputs are approximately the same. Please help me out. I am just about ready to maiden an electric 92" ASM A-26 and would like to hook both BEC's together in parallel with a separate NIMH battery pack. I just lost and electric ASM P-61 when my primary flight battery failed and I had no backup power with a separate pack. Some one with more knowledge than me of how a BEC works should be able to advise me as to why this can be done or why it shouldn't be done. PLEASE HELP. Jerry

DaveFlynn

Some BEC's can be connected in parallel some can't. Contact the manufacturer to be sure, but usually the switching type can be paralleled. Some linear voltage regulators will oscillate if hook to each other.

I see no reason not to connect a battery so long as the voltage of the BEC is more than the batteries stand-by voltage, otherwise the battery will discharge. Testing one of my NiMH packs it measures 4.98V with a 1mA load (4.7KΩ resistor).

The common practice is to use a Schottky diode on one of both sources to prevent one from overriding the other or a short in one from shorting the other. P/N:S10A, Digikey:S10A-TPMSCT-ND

jtbuck

Hello Jerry, 

I am curious if you worked this subject out at all... I am brand new to the electric side and building a Habu 32 DF(the reason why i am now electric).
woah.... alot to learn about the battery hook ups.  I have read a ton of info and fairly certain I at least know what I am buying  (i am going with the CC Pheonix ICE 100 ESC w/BEC and a 6S (Hop-Up)Mega motor with (1) 6S 5000mah 45C lipo...I really want to have the separate 4cell Nimh battery for the receiver as a backup battery also (after reading some ESC failure Horror Stories) and here is where i am lost and just prodding people for more information.

When you say BEC in Parallel, would this be another separate BEC connected to the LIpo and plugged into the nimh bat? 

ug..  and I was getting tired of chasing 2 stroke needles?  seams like a breeze compared to this...LOl..

Any Info on this subject or any other relevant subject greatly appreciated. 

BarracudaHockey

My Feedback: (11)

If you're running a battery, why would you want to run the rx off the bec as well?

Redundancy?

DustBen

My Feedback: (3)

I tried this idea... running the BEC thru the throttle channel and a battery thru the power port... The wires from the Nicd to the receiver melted in seconds and the ESC never worked again.

I'm not saying this applies to all ESC's, but be prepared to pay a price

Rodney

I highly recommend that you not hook them in parallel. Even with the better designed ESC's, you risk damaging them if you try to parallel them with a battery. I will ALWAYS disconnect the red wire between the ESC and receiver if using a battery to power the receiver and servos.