aerosquare

Hi Jeff,
as I am approaching my Maiden Flight, I am about to decide which battery to buy. At the moment, I have those EDF and ESCs in my A320:
http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6632 http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6456&Product_Name=Hobbyking_SS_Series_15-18A_ESC

Which LiPol from HC would you recommend me, if would I give one battery for each engine? Or, which one would you recommend me for both engines together? Later on, I will decide if to give only one accu (cheaper and the same voltage for both engines ->the same RPMs and not so heavy) or to give one for each engine separately (not so cheap, heavier, but safer)

Regardless about the batteries for engines, I wish to have one separated battery for Rx and Servos. Could you be so kind and recommend me one? I have 5 servos (2 ailerons, 2 pitch, 1 rudder+nose wheel steering), 4 of them are Hitec HS-81, rudder one is some no-name from HC, equal to HS-81. The Rx is standard 40Mhz Multiplex PICO, unfortunately I don't have 2,4GHz radio.

Thank you in advance for your advise, I really wish to avoid so sad situation which you faced after electronic failure

Pavel Brodsky

Hi Pavel,
These fans are the same I used on my ME 262. They are quite powerful, but I'm afraid your ESC wont stand the amps. I measured about 32 amps on the bench PER FAN! Of course in flight you rarely use full power (at least on the ME 262). But be careful not to smoke your ESCs.
Regarding batteries, it depends on the total weight of your model. I would suggest that you stay below 2kgs auw to have a good power/weight ratio.
Again, on the ME 262 I used one single 2250 25C 3S lipo to feed both fans. Which is really the max that this lipo pack can sustain. But as I hardly ever use full throttle that's ok.
On the Airbus, if you choose one pack, you should buy a 25-30C rated pack around 3300 mah capacity. Maybe bigger, if your plane is not heavy. Or 2 packs around 2000 mah. The Rhino 3S 2250 I have for my Messerschmitt is 190g.
Finally, to power the receiver and servos, you're definitely right to use a separate power source. That will save you a lot of trouble. You can use a 4 cells nimh pack. But another good solution (lighter also) is a separate ubec.
I bought this one from Hyperion for my new Sabre F86: http://shop.lindinger.at/product_info.php?products_id=64696
Haven't flown the plane yet (too windy these days) but this thing seems to work pretty well.
Hobbycity also sells similar products. But I haven't tried them. Advantages of a ubec: lighter than a receiver pack, no extra battery pack to charge and look after.
One important thing to know:
IF YOU USE A SEPARATE POWER SOURCE (EITHER BATTERY OR UBEC) FOR RECEIVER AND SERVOS, ALWAYS DISCONNECT RED WIRE FROM ESCs GOING TO RECEIVER!!!
If you don't do it, you could damage or even destroy all the electronics
Hope this helps, have fun
Jeff

Amazing help! Thank you very much.

QUOTE:
jeffT wrote:
IF YOU USE A SEPARATE POWER SOURCE (EITHER BATTERY OR UBEC) FOR RECEIVER AND SERVOS, ALWAYS DISCONNECT RED WIRE FROM ESCs GOING TO RECEIVER!!!

Please could you describe which wire is it? I have some ESC cabels with a diferent colour marking... but as I am thinking about it - is it enough to cut only one wire, or do I have to cut both power wires?

Hi Pavel,
The red wire (+) is the central one on the connector going from the esc to the receiver. This is for JR/ Futaba connectors, which are standard today. Older Sanwa connectors had the + on one side which could lead to invert polarity and destroy rc equipment

If you have an external ubec or battery pack to power the receiver, you should disconnect the + wire on EACH esc.
if you're still unsure, you can ask somebody at your rc club or post a photo.
JF

Solved. Thanks! Hope it will be good weather this weekend, I am ready for maiden flight