External bec wiring

[1911kevin]

I've been trying to figure out how to wire a bec to my mmm. I know about where it plugs into the rx and to run a servo extention wire without the red wire from the esc to the rx.

My question is where to attach the power wires. I know they go to the wires that go to the batteries but if someone could give me more of an explination on this part id really appreciate it.

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[50togo]

I opened up the esc case and wired it to where the battery terminals attach to the esc
But then I ran the bec hot directly to the servo and left 6v to the receiver

[1911kevin]

I understand what you mean by opening up the case and wiring to the battery terminals but can you elaborate a little on the direct power to the servo.

I'm running a high voltage servo (7.4v) and a fan on the motor and esc so I'd like to give the servo the power it needs without burning up the fans.

Sorry if that's not correct thinking but that's why I'm posting. Just trying to get this all figured out.

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[BL-Bob]

That's a great place to feed one from but it voids any remaining warranty. It also depends on what the new bec's max input voltage is. If it can handle 25 volts most guys solder the leads across the serial harness of the Mamba. black to black, red to red.

IMO, The fans won't care about 2 extra volts.

To wire direct to the servo, run the bec output wires to the red and black wires of the servo but leave the white/yellow signal wire in the ch 1 RX.

[50togo]

This might be hard to explain
I took a Y extension -plug it into the receiver and one side plug it to the esc other plug to the bec after I cut the power lead in the middle of the extension. Took another extension ran it to number 1 on the receiver cut the power lead in the middle of the extension then plugged it to the servo. And the hot from the bec to the servo
This way no cutting or removing pins
You could remove pins and move some around

[chapinb]

Imagine the 'bec' is actually labeled 'battery'. Dont forget to only use 1 battery, not the power from both batteries in series.
Leave the servo signal wire connected to the receiver, but attach the pos/neg of the servo directly to a single battery.

Fans will be fine on 7.2 if its easier, but they may burn out slightly faster than they would otherwise.

[50togo]

I am using both with my castle bec with no problems

[1911kevin]

Ok. I think with everything layed out infront of me this will be a little be easier to understand. Besides giving my servo the power it needs I'm having a problem with the e revo stuttering on acceleration. It doesn't happen all the time but when it does ill just be rolling on the throttle and it will cut out and then come back causing a wheelie or the slipper to squeal.

Will the bec also fix this issue or is there something else that causes that?

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[50togo]

What batteries are you using?

[1911kevin]

Venom 3s 5400mah 20c

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[50togo]

20c are kind of weak probably need stronger batteries

[snookerd1206]

Also what firmware is your esc running?


Sent from my iPhone 5

[87 GN]

1.24 beta, has the least amount of cogging....



Venom 3s 5400mah 20c
your batts are 108 amp, that is a little under rated. But you should be ok if you keep your gearing conservative.
18/54 ish......

here is how I wired in my Ext BEC
http://traxxas.com/forums/showthread...=1#post5394611

you are prob just getting brown out, but you might set your throttle end points again.. & might need to by pass the on/off switch..

[JustinThyme]

Are you running a single battery or 2x 3s? 20c is pretty weak, need at least 40C.
Im running dual HV servos chanel 1 and chanel 3 (because I can) and ditched the BEC altogether. Im using the balancing plug from one of the lipo packs. Using a balancing extender with a servo connector mounted on the other end I just tapped off to get 2s and ran that to my receiver (My futaba R614ff is rated for 7.4VDC dont do this if your RX isnt rated for it) and using a short servo extension I clippied the positive lead off and connected my ESC with that. This gives 7.4V to everything but the ESC with one tap and no BEC.

[1911kevin]

Running 2 3s packs. And the burst is rated at 40c. The first set of packs I got were 3s 5000mah 50c but they didn't last.

I'm understanding this a little but some of the posts are just confusing. Not your guys fault, sometimes when ya know what your taking about its hard to dumb it down. Lol

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[JustinThyme]

More often than not the battery rating from the manufacturer is fluffed, personally I shy away from anything that has a "burst rating". Fine example is MaxAmps. True 100C rating is what they claim. Well on a 5000mAh battery thats 500amps! The wire would melt in a skinny minute if you could find an ESC that could pull that much. Bottom line is if you hit the throttle and it stutters the battery couldnt supply the current needed regardless of its rating. 20C would be OK in a 1/16 scale but anything over that it just doesnt have the punch needed in even a 1/10 scale let alone a 1/8 scale. The ERBE is going to hit you up for around 2500 watts of power at full throttle. Lets do a little math for 6s 5400mAh.

2500/22.2=112.61amps
5400mAh=5.4amps
112.61/5.4=20.85C
20.8x1.4=29.19C peak

Standard good pratice is never to run anything past 80% of its rated load so using peak..
29.19x1.25=36.48C
Closest size larger=40C given that its still 5400mAh.

Just math but take it for what its worth, a little advice.
Put in decent 40C packs and your acceleration problem will disappear.

[87 GN]

this is how Castle states to wire the BEC


===


what happened to the 5000 mAh...??

[1911kevin]

I was running the 3s 5000 in a slash and had a meltdown. Can't give an explination because I really don't know what caused it. Ruined a chassis and an esc and a body in the process. so I sent in the battery that didn't explode and they sent me 2 5000mah 20c's. This was before I had a smart phone so I couldn't email them and trying to call them and leave messages got me no where so I just ran them. Now I'm left to deal with the stuttering on acceleration. Ya live and ya learn I guess.

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[MITCH316]

I was running an external bec installed as posted above...it went faulty on me. Its not fun when you running full throttle and your truck decides to go right.

I think I destroyed the bec bashing the way I do...I have now removed it and running my hitec 7950th off my MMM esc and bumped its internal bec to 6V with the field link programmer. I am also running the latest firmware.

To be honest...I don't notice any difference in performance with my servo, its still very responsive and quick...no brown outs or glitching either. I only use my truck these days as a basher.

[Money pit]

I soldered a jst pigtail directly to the battery wires inside the esc case and a male soldered onto the bec. I had this setup when it went up in flames and castle said nothing about it. Make sure that it has some kind of airflow though, mine got warmer than I thought was acceptable when it was next to the esc and the motor. Now I have it on the second motor mount of the dual plate. With a slipstream body the air hole is blowing right on it, hardly gets above 90°f in 80°f weather.

[clp71220]

This drawing shows the power of two batteries for power. The negative wire from the CC BEC needs to be between the batteries. Or you could move the Positive wire from the CC BEC in between the batteries. You just do not want that much power on the supply side of the CC BEC.

Imagine the 'bec' is actually labeled 'battery'. Dont forget to only use 1 battery, not the power from both batteries in series.
Leave the servo signal wire connected to the receiver, but attach the pos/neg of the servo directly to a single battery.

Fans will be fine on 7.2 if its easier, but they may burn out slightly faster than they would otherwise.

[65535]

This drawing shows the power of two batteries for power. The negative wire from the CC BEC needs to be between the batteries.

DO NOT WIRE YOUR CC BEC WITH THE NEGATIVE (Common Ground) WIRE BETWEEN TWO SERIES BACKS. THIS KILLS THE BEC. It also likely damages your ESC and possibly even batteries and wiring, just don't do it.

That image is the proper way to wire a CC BEC in parallel with your ESC, it is exactly how I have mine wired. The one change I have and how I would recommend doing it is adding a ground wire (black) between the Servo and the Receiver. As drawn the signal path for the Servo ground wire goes through the BEC through the ESC and finally reached the Receiver.

[paulfromtulsa]

what is the point of running a external bec? doesnt the mamba monster already have a internal bec? so essentially are you running 2 becs

[50togo]

One is to take the load off the internal bec -it is weak
I used one mainly to take advantage of my hv servo at 7.4 volts internal is 6 volts
And some servo's like savox need more amps then the stock bec can supply and you usually bypass the stock bec in the process

[BL-Bob]

this is how Castle states to wire the BEC


===


what happened to the 5000 mAh...??

The top picture is for wiring a 6s bec onto a 12s system. I can see it misleading some guys wiring a
more common 4-6s revo.

[87 GN]

^ now I'm seeing it, good catch, so that means wired like above you would only get
2s~7.4v
or
3s~11.1v

so what does that really mean as far as amps & volt going to the Ext BEC..??

[JustinThyme]

The external BEC clips the input voltage to regulate it and dissipates the excess as heat. Too many volts to clip=magic smoke gets out. The castle 10 amp BEC is a fixed linear voltage regulator. Heat generated as follows. For 2s and the BEC set at 6V the equation (7.4-6)x10=14.4 watts of heat. 3s (11.1-6)x10=51 watts of heat. Now jack that to 6s (22.2-6)x10=162 watts of heat and so on. Personally I would never wire it past 3s in an Erevo, no need and its just draining the battery and dissipating the excess voltage as heat that you dont want anyhow. When I had mine installed before I ran straight off the balancing connector for power with a balanicng extension I had it connected to the same negative as the ESC and the positive of the first battery in series as shown in the above drawing. The castle BEC pro is a switching regulator and does not dissipate the excess as heat. It simply switches on and off to keep the output DC capacitors at the desired voltage and why it is capable of handling 12s.


Lucky post #777

[ksb51rl]

The external BEC clips the input voltage to regulate it and dissipates the excess as heat. Too many volts to clip=magic smoke gets out. The castle 10 amp BEC is a fixed linear voltage regulator. Heat generated as follows. For 2s and the BEC set at 6V the equation (7.4-6)x10=14.4 watts of heat. 3s (11.1-6)x10=51 watts of heat. Now jack that to 6s (22.2-6)x10=162 watts of heat and so on. Personally I would never wire it past 3s in an Erevo, no need and its just draining the battery and dissipating the excess voltage as heat that you dont want anyhow. When I had mine installed before I ran straight off the balancing connector for power with a balanicng extension I had it connected to the same negative as the ESC and the positive of the first battery in series as shown in the above drawing. The castle BEC pro is a switching regulator and does not dissipate the excess as heat. It simply switches on and off to keep the output DC capacitors at the desired voltage and why it is capable of handling 12s.


Lucky post #777

So... you are claiming this is not true?

CC BEC, 10 amp max output, 6S max input,4.8 - 9.0 volts, Selectable output...
Thank you for purchasing Castle Creations’ CC BEC switching power regulator. We think you’ll find it to be the most capable and flexible BEC on the market. Please use this product within its capabilities

The above is the text on the packaging of the CC BEC (not Pro.)

FWIW, guys the CC BEC works fine on 4S or 6S. I run in off both packs in my ERBE and have for about 3 years. It's got a 12S limit - 6S does not make it sweat.

[JustinThyme]

So... you are claiming this is not true?

The above is the text on the packaging of the CC BEC (not Pro.)

FWIW, guys the CC BEC works fine on 4S or 6S. I run in off both packs in my ERBE and have for about 3 years. It's got a 12S limit - 6S does not make it sweat.

Dont have the package so I cant say one way or the other but my bet is that its false. 12S limit is definitley false. Right on their spec sheet


http://www.castlecreations.com/products/ccbec.html

Max volts
5v to 25v
2s to 6s LiPo

[ksb51rl]

Dont have the package so I cant say one way or the other but my bet is that its false. 12S limit is definitley false. Right on their spec sheet


http://www.castlecreations.com/products/ccbec.html

Max volts
5v to 25v
2s to 6s LiPo

Darn spec sheets side by side! You are correct - 25V / 6S is the max. 12S was for the Pro on a heli.
Thank you for the heads-up!

You can find images of the packaging here:
http://www.castlecreations.com/support/documents/cc_bec_user_guide.pdf

[JustinThyme]

No biggie, we both had inconsistancies. I havent dissected the 10amp BEC, I sold it off when I ran straight from the battery, using all HV servos and my Futaba R614 RX is rated for 7.4 so I dont need it and passed it on to someone else who could use it. Looking further at the spec sheet the fact that its current capacity diminishes as voltage increases is a classic drop off for a fixed linear voltage regulator. At 6s its down to 5 amps where the pro is 20 amps thoroughout the entire range as switched regulators normally are.

But on the other side of the fence its output can be changed so that leaves several options up in the air. It can be switched or it can simply redirect the voltage drop across different RC networks to obtain the desired output. Maybe its a Hybrid LOL. The only way to find out for sure is to dissassemble Johnny 5! Im sure Castle isnt getting off the schematics.

[87 GN]

OK I'm going to read all ^that a again, for the I don't know how many times.......

So to wire it up in series (like in the lower right hand corner of the guide sheet) where it says never do this...
With 2/3s that will get you to the Max 25v............correct......

[JustinThyme]

OK I'm going to read all ^that a again, for the I don't know how many times.......

So to wire it up in series (like in the lower right hand corner of the guide sheet) where it says never do this...
With 2/3s that will get you to the Max 25v............correct......

Yes it will

[87 GN]

it's all coming together now........LOL
sort of, so say you are only running the Ext BEC at 2s.....7.4v instead of 25v
is there a question in there^^??


thanks.........

[BL-Bob]

http://traxxas.com/forums/showthread...50#post5403650

[JustinThyme]

it's all coming together now........LOL
sort of, so say you are only running the Ext BEC at 2s.....7.4v instead of 25v
is there a question in there^^??


thanks.........

I only ran it on 2s, no need to work it harder. Wasnt that big of a deal to run the wires right up with the battery wires ans solder them in with the connector. Im not even using a BEC now. Using a balancing lead extension with the male end replaced with a servo male connector. I dont run above 5s, mostly 4s so its not too hard to connect the lead to the batteries balancing lead when I put the battery in. If you run 2x3s packs it can still be done with a 3s balancing extenion, just have to tap it for ground and cell 2 to get the 7.4 Volts. Again this is only good if you are running HV servos and depending on how you wire it a reveiver that will handle the 7.4 volts.

[BL-Bob]

^When you run without a bec your servo(s) slow(s) down as the pack voltage drains. 2s direct wired servos can see anything between 8.4 to 6.0volts, even 7.4 sometimes.

[Qtop]

I just ordered a cc bec 10a for my MMM. Do I need to connect it directly on the esc power cables if I am running 2 3s packs?
Or just on one pack so it will use only 11,1 volts?
I know the bec can handle 6s, but I need to be sure I am connecting it propperly.

Also what channel on the reciever do I use for the BEC cable? (5 channel tqi reciever)

Last question: Do I really need to use an external BEC on the MMM v3 or not? (just using the stock servos)

[Money pit]

Wire it to the positive/negative of the esc and it is fine, any open port, and no it is not needed but will not hurt anything. Make sure you disable the esc's bec if you use the external.

[Qtop]

Ok thanks. Maybe instead of a CC Bec it better to install a CC cap pack?