Is a 3A ubec enough for standard digital servos?
Many kit manufacturers say use a seperate bec and then dont say what sort of current capability to look for.

Should be plenty for 4 or 5 of them, unless you are using them in a bigger 3D heli or something. The Castle BEC just came out and it's pretty stout. I have one in my 3Dhobbyshop Aspera (4 HS-65's) and plan to use another one in my Hyperion Katana F3A and 24% Extra 300. The Extra will use 5 digital high torque standard's...

How many servoes, size of plane and flying style? 3A isn`t enough if you have a 2-meter 3D-plane with digital servoes, not close to enough.

That is what I thought. So what is the average/max current draw of a standard digital servo in a 2m ship and what are people using to power the servos and receiver if this is too much?

If you have 4 of 10kg servoes (aile/elev), and one 20 kilo (rudder) theoretical the peak amps could reach 15A in a snaproll at high speed. 10A peaks is guaranteed reached during hard 3D-flying.
The cheapest, safest and also best choice is to use good NiMh-batteries for receiver And course cables.

Some digital servoes have failsafe, and they might "lock" during hard manouvers because of voltage drops in long cables. Some receivers might also suffer from this...

From experience in the IMAC-club in Norway it s said even the Fromeco-setups is not safe in models above the typical 2,3meter/50ccm size because of voltage drops. Analyzing some crashes with the Weatronic receivers onboard showed excessive volt-drop...

NiCd or NiMH still proves to be safe and cheap

A very interesting reply. almost have come to that conclusion exept that with electric planes we are always considering weight and a rx airborne pack is rather a heavy component compared to the ubec but I suppose in the larger models the percentage addition of weight is far less.

What do you guys think about the new Castle Creations BEC 10 amp setup? Just got two of them for my smaller planes, but I'd like to try them in my 2 meter ship. I'm worried that I might electrically "overstress" the system. This will also be used with a new JR 12X if it ever comes out. I don't really care about weight since I'm not now or ever will be a NATS level competitor. I'd just like the simplicity of one battery to manage in the plane. I use 8411A's throughout since that's what I had at the time... John

ntsmith: The extra weight won`t necessary be too high. You might be able to power the gadgets with a 2200mAh good quality NiXX which is able to deliver the required power. I have used 1700mAh NiCd in some of my 2-meter planes, with 5-6 digital servoes, with success.

Also remember all the advanced servoes and receivers might in fact be the weak point in the chain. There might be "safety"-settings like failsafe etc in some of the servoes which won`t help, but cause a crash. Using good analoge servoes, and avoiding the fastest servoes also will keep the dramatic current peaks much lower than the worst, ultrafast digital servoes. It might be better with an analog servo which is sagging a bit than a digital servo which have a hugh holding-power kicking in.

patrnflyr: I saw a short review of the CC 10A BEC. But the review didn`t show any useful measurings. I would like to see the output voltage on an oscilloscope during different loadings. Only then could we see if the gadget is worth the money I have measured some UBECs myself, and some of them worked really good. But I have also found some which never will be installed in any of my planes... Really bad voltage variations, and excessive peaks which are far above specs for servoes and receivers.
One funny thing with the release of this CC BEC is the advertising: They say it is a 10A BEC, but when you read the specs it shows it is a 7A BEC, or a 5A BEC if you wuld like to use it in a big model... They are honest enough to mention the UNI-plug is not rated for 10A. In fact it is rated for 3A... But if you would like to use a simple power-list to distribute the current outside the receiver it is not a big job to solder in some good cables and solder directly to the list.

Anyway: in a 2-meter model things would usually work well. Especially if you fly pattern. I would say the magic and dangerous limit is at 2,4 meter, if you include 3D-manouvers as a habit

Remember other points of danger: long and tiny cables, cheap switches, failsafe settings way off, mechanical binding at endpoints and much more. The KISS-principle is still valid, and rely on your own experience and knowledge. (Anyway, discussing is always interesting).

Happy landings

You'd be crazy to use a BEC in a pattern sized airplane. I use a 910ma 2 cell TP Prolite lipo on the Rx. Digitals all the way around.