To bec or not to bec that is the question - RC-Monster Forums

slimthelineman · **To bec or not to bec that is the question -** 03.28.2011, 11:51 PM

Hey fellow monsters here is my dilema, well more of a choice but just wondering what my fellow monsters and possibly the cc crew think. I have sitting in my pit bag a nip ccbec. Currently running a mmpro on 6s with a tekin t8 1400kv motor a futaba bls452 brushless high tourqe servo and a sr300t receiver with temp and rpm telemetry. My question is would it ease the load on the esc to run an external bec instead of the built in one? By no means does the esc get hot or brown out the rx. Assuming the higher input voltage enables the bec to work better? Using motor brakes too and just thinking using the external bec might keep the mmpro happier? Don't get me wrong this is an amazing esc and I currently run three of them in my race vehicles, but I know it's not really intended for 1/8. The car is about 7.25 lbs rtr and the 6s 1400 combo seems to pull minimal current but I will have to throw the watt meter on it to get a ballpark of average current and spikes. So what does everyone think? External bec or internal?

03.29.2011, 01:06 AM

I would run the external bec, takes a load off the esc and it will lower temps

Cheers

fastbaja5b · 03.29.2011, 01:08 AM

+1 on the BEC, you're already running the ESC over what it was designed for by putting it into a 1/8 scale car. Best not to push it.

slimthelineman · 01:21 AM

Don't really think it's being used beyond it's capabilities. It comes stock in the sc8e with a 2200 which on four cell will draw twice as much current as my setup. Not to mention it's probably at least a pound heavier than my rig. Esc comes off the track after a five minute run at about 100f so heat is not an issue. Will probably throw it in anyway to eliminate the possibility of a bec failure. Just wanted to see what others thought since it works fine with the internal bec.

Mostly wondering if the higher input voltage helps the bec out a little. Seems like the mmpro works better for me on higher voltage. No brownouts in my two wheel and four wheel sc's on 3s using brushless digital servos like others have on 2s.

scarletboa · 03.29.2011, 09:56 PM

The MMP has a switching BEC, so even on 6s, it should only generate minimal heat. The only reason I can see for running an external one would be if you are using a high torque digital servo.

Arct1k · 03.29.2011, 10:03 PM

I have a cc bec/ bec pro on all of my rigs - 2 on one :)

BrianG · 03.30.2011, 11:24 AM

To the OP: I would use an external BEC if it were me.

slimthelineman · 03.30.2011, 05:22 PM

Was pretty much planning on using it when I got it anyway just wanted to hear some opinions. Actually pretty impressed with the internal bec being able to handle the high tourqe digital servo, personal transponder, and all the telemetry as well. Weak bec my a$$! Kinda what I always found with the mmpro though, 2s is where the issues lie with brown outs and such. Never had so much as a hiccup on 3s and up with digital servos and the like. I'll post a pic after I squeeze it in somewhere on the rig.

BrianG · 03.30.2011, 05:28 PM

I've had the MMPro BEC exhibit problems on 3s and 4s. Maybe it was an earlier model, but I had 3 that all did the same thing. I found the BEC would basically drop out at anything over around 2-2.5A. Spektrum receivers especially don't like this.

slimthelineman · 03.30.2011, 05:58 PM

Wow that sucks, never checked what kind of current I was drawing. Maybe I'm just lucky, ha ha ha. What kind of motors were you running on those setups with the issues. I've always ran like 3400kv or less on 3s and higher not sure if that has anything to do with it. The only time I had an issue was with a 4.5 550 on 2s I used in my scrt10. But it wasn't the digital servo that did it. Was only when I would punch it off the line I would get a brown out. Cap fixed it, but switched back to my fav setup of a 6.5 550 on 3s.

03.31.2011, 01:12 AM

Quote:

Originally Posted by BrianG

I've had the MMPro BEC exhibit problems on 3s and 4s. Maybe it was an earlier model, but I had 3 that all did the same thing. I found the BEC would basically drop out at anything over around 2-2.5A. Spektrum receivers especially don't like this.

Mine does the same and its a recently purchased MMP

Just running an Ace DS1015 Servo in my Slash 4x4

Servo draws 3 amps or so and the bec voltage drops to under 5v

Tried the cap and it helped a little but was still not stable, ccbec installed and all is well

People blame the Spekky recievers but I think its just that they dont like voltage drops, other recievers / servos are still seeing a drop in bec voltage, just handling it a bit better

Cheers