TO BEc or NOT TO BEc...not just for Patrick

[BrianG]

The CC BEC is a high quality BEC, it just uses a discrete component design. All the other ones I've seen (barring the DimensionEngineering ParkBEC) use a circuit on a chip where the switching FET is integrated into the package. So, they probably use some kind of catastrophic failure circuit. All of those designs based on the common IC are limited to around 3-3.5A, whereas the CCBEC is rated for much higher.

[Sammus]

Originally Posted by coolrunnings

External bec's are known to fail as well I had a coolflight ultimate bec go on me and I've also read here on this forum that the castle bec fails and takes the servo with it because they send full battery voltage to the servo, a high quality unit like a hercules or a dimension bec is the only way to go.

Ahh dissing castle again . Upon failure they not only (potentially, depending how it fails) send full voltage to the servo, but to the receiver as well, which will usually kill it.

Yet another reason to stick to the internal BEC. :)

The castle esc is also apparently a little more noisy than the other brands mentioned (koolflight, herc, dimension) and can cause glitching if you have it near enough your antenna or rx.

Yea your right brian...my herc bec says 3.5 amps I'll try and limit myself to 5 servos or less.

[Sammus]

Don't be so quick to take the piss, I read an article (and for the life of me cant find it right now) about some guy testing a bunch of newer high torque servos - I think it was the JR series that have super high torque (like figures over 400oz.in) that were drawing 4A or so with minimal load on them. The bright side is that fully loaded peaks weren't much higher - still under 5A...

[hoovhartid]

well, thank you all for the input!

I set up my MMM v2 w/o the BEC and its kickin @$$!

I ran my e-revo with two zippy 4300 20-30c 3s run in a series for (6s)
Lasted about 20 minutes. VERY powerful

My zippy's looked a bit puffy tho. They came out at about 135F

doing more testing in a bit.

Charging my TRC 15c 8000's (4s)

[J3110]

Whooo!
I'd check your temps a lil more frequently when you run those TRC cells simply because they'll last longer and gone unchecked, you could end up with more than a puff...maybe smoke...or FIRE even!
j/k: you know I'm just jealous.
Flog that sucker, Hoovhartid!

[hoovhartid]

Originally Posted by J3110

Whooo!
I'd check your temps a lil more frequently when you run those TRC cells simply because they'll last longer and gone unchecked, you could end up with more than a puff...maybe smoke...or FIRE even!
j/k: you know I'm just jealous.
Flog that sucker, Hoovhartid!

Just got back from jammin my TRC's



The temp outside was 95F. Motor got to 185, batts got to 120
ESC fan turned on a few times, but averaged around 160-140.
Still goin strong. I'm gonna give it hell. It seems to like it

Got the e-revo geared for about 40 on 4S, and 60 on 6S.
Might gear it down a bit to see if it lowers the temps overall

I think the temps are just going to be high do to the heat outside tho.

A servo that draws 4amps? My hs-5955 tg 333oz beast is pulling about 220-330 ma (5v/6v) with no load and around .5a (500ma) with load which sounds about right with the dimension sport bec specs that state 6 digital servos.

[Sammus]

Mate since when were we making personal attacks? I was just trying to help.

Did you measure your servo current with an oscilloscope? unless you have one your readings won't be accurate at all. Here are some readings of a few servos, 1.8A for an analogue 200oz servo. Or if you want to whinge because that's quarter scale, the one to the left is a regular size analogue 100oz high speed servo. Still not even digital.

[BrianG]

OK guys, take it easy.

coolrunnings: What did you use to get those current readings? I've tested a Hitec HS-5945MG (180oz-in @ 6v) and it pulled 2.4A under typical steering load. I wonder if the meter (or whatever) you used had a sampling rate too slow to capture the current peaks?

I got this info from a guy named Randy Moody at r/c dude hobbies, he did not use any testing equipment that I know of, I think it was best guess going by what he read on my servo's spec sheat and from info he's gathered over the years on the dimension bec's...he was supremely confident that my sport bec would handle at least four of the 5955's I mentioned as stated by dimension. No I didnt test anything.