To BEC or not to BEC..that is the question/

[karlhh]

I would think that the extra weight would off set the difference. just my thought.

[searay skipper]

kinda starting to get to my original question about advantages and disadvantages......keep it coming please.

Right off I can see an advantage I guess...getting rid of a dedicated rx battery pack. but do disadvantages outweight that?

trying to learn guys.........the best ways to go about things while getting my feet wet.

[runzwithsizorz]

I would think that the extra weight would off set the difference. just my thought.

Some boats, mostly mono's, darn near require extra weight to stay planted. IIRC, there's a Titan 33 that *races* with a full pound of lead, I think Fluid could confirm.

[runzwithsizorz]

What about the parasitic draw a BEC puts on your main LIPO packs? Whether you're running a HV (5+ cells) or =< 4 cell setup, won't using using a seperate 7.2 V battery pack to power the RX & servo give you a slight advantage in usable voltage & amps? JIM

My thoughts exactly. Hitec states that, "a rule of thumb is around 2 amps for the average servo". Some of the more beefier servos 150oz.in+ would be??? Something else to consider is run time, I'm not ready to do this now, but perhaps
someone else with an RX pack could chime in with the mah draw, of say, a 4 minute sport run.

[1945dave]

Well I learned the hard way long before BEC's and fast electrics that receivers have limited power available through the receiver to the rudder servo. On my 17 pound twin nitro 90 hydro many of us were using three servos in parallel to crank over the rudder or some of the the guys used very large 1/4 scale servos. My first experience after buying one of the $75.00 mega servos was to curse it out saying right out of the box it did not work. In truth it worked fine but drew over 7 amps under load and the reciever said bye bye. Soon we understood how to rewire the same battery pack so that only the receiver provided the servo instructions and the wired directly to the battery provided the voltage and current to power the servo without pasing this current through the receiver. Now with that said I believe the BEC concept is perfectly fine for powering the receiver and even a standard (less than 3 amp) rudder servo. If you have any temptation to run a heavy duty digital servo or large size rudder servo because your model needs this power then by all means go to a seperate 6 volt battery supply.

Regarding the concern for drawing away from our high current lipo batteries some of the capacity and power available to the high amp draw electric motors, I think this is no issue at all. Even the strongest and most demanding of receiver servo combinations draws less than 1 amp average per 5 minute run with the radio portion of the receiver being under 140 ma and the low load on the rudder servo while going straight line under 1 amp. Hard turns for what ever time that portion of your run takes will generate the 2 to 3 amp short term demand on the battery but so what. Futaba 4.8 volt 600 ma NICd receiver packs are normal and last all day for normal racing. I built several 6 volt 2,000 ma packs for my heavy demand two engine hydros and never had any concerns about capacity or available power.

Dave

[JIM MARCUM]

Dave. But, for big S/T Offshore catamarans with 70+mm long rudders, I prefer to use 7.2 Volt 2000mAh NiCad battery packs to power the RX & large servo.

I've raced everything from drag races, catamaran sailboats, 1/10th scale RC Off-road buggies & trucks, 100+ mile off-road motorcyle desert races, and now FE boats. I have won 1st place trophies in all - except FE boats (maybe soon). As a racer, I know racers will do everything they can to get even a small advantage over the comperition. That is why I run seperate 7.2 Volt battery packs. JIM (AKA: 1945JIM)

[runzwithsizorz]

Dave. But, for big S/T Offshore catamarans with 70+mm long rudders, I prefer to use 7.2 Volt 2000mAh NiCad battery packs to power the RX & large servo.

I've raced everything from drag races, catamaran sailboats, 1/10th scale RC Off-road buggies & trucks, 100+ mile off-road motorcyle desert races, and now FE boats. I have won 1st place trophies in all - except FE boats (maybe soon). As a racer, I know racers will do everything they can to get even a small advantage over the comperition. That is why I run seperate 7.2 Volt battery packs. JIM (AKA: 1945JIM)

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70mm= aprox. 2.3/4in. Ya need ta add a few more +'s Jim, a lot more!

[Diesel6401]

Anything over 4s I tend to use a rx pack and dis-able the esc's bec, the exception of this being the CC Ice 240 which I run the 6s on with the bec enabled however I personally am not the biggest fan of of CC esc's including my ice 240 which crapped out on the first run. Castle graciously replaced the esc as it was only 3 months old and they're CS is awesome. I LOVE the castle motors and I LOVE the're 10amp bec and use that is some of my planes, but I to date I am in no rush to put a CC esc in any of my planes. Don't have the full trust with them yet, I perfer hobbywing esc's over any other esc in my sc10s, boats and planes. I have been liking the Hifei esc's as of late though, I haven't tried one in a plane yet but would like too and try out they're intergrated data logging. I'm very picky on which esc's my favorite planes get. If its a cheapo plane I care less, but a good plane it only gets what I trust. A esc crapping out at 75mph+ in the air doesn't yield the best results!

[JIM MARCUM]

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70mm= aprox. 2.3/4in. Ya need ta add a few more +'s Jim, a lot more!

Sorry, must have measured the length of my penis.

My S/T cat rudders are 6 5/8" overall, 1" to 1 1/4" wide, and 4 1/4" max in the water. JIM