BEC from esc

[lowndsy]

Morning gents. My Quicrun ESCs have a 5v BEC built in which I want to use to power the receiver, but there is no extra wire or anything so I'm stumped on how to use it. No instructions with the esc, obviously....

Do I have to split a cable out into the receivers dedicated power channel, or does all the lovely electricity just flow through the normal channel connections?

[teamshock]

You just need to connect the rx cable as you would normally. The BEC will work just fine.

I've just bought a load of Quicrun ESCs for my students and I'm pretty impressed with them so far!

[lowndsy]

brill, That's what I was hoping you'd say!

Yeah, the Quicrun looks quite handy, and unlike the other escs I bought they actually turned up!
I'm using the 4s dual output units so I might be tempted to use them to go 4wd one day.

[cjsowry]

I'm happy with them in my bot. The duel output for two motors very handy for a 4wd. I've read that if you have more than two esc's supplying the BEC problems can occur. But with running two for the drive everything is grand. Waiting for my actuator to arrive so I can test three BEC's into one receiver.

[RobotExtreme]

Hi,

You must use just ONE BEC per RX, if you use more than one BEC per RX bad things can really happen, why?

Battery Eliminator Circuit (BEC) is nothing more than a Voltage regulator that "reduce" any voltage at input for a given voltage (~5V) at output, the question is that the ~5V is a undetermined value, when you plug two BEC at the RX, each one is delivering their own voltage to the RX, the problem start here.

Example: One is delivering 5.2V and another 4.9V, the RX is "burning" 0.3V inside. More than this, today in order to reduce space and improve efficiency, most of the ESC use "active" voltage regulator "monitoring" the output and when the BEC "see" a obnormal voltage at their output, very bad things happen. My advise, remove the red wire of all ESC less one.

About the Quicrun:

Attention for the fact that the ESC have different current limit on both directions (60A Forward, 30A Backward) you must swap the motor wires in order to have the forward on both motors when the robot move forward, since the "Forward" is used harder than backward on ours purpose.

Guilherme

[lowndsy]

Thanks Guilherme. I knew about switching the polarity on the motor (soldered up a little XT60 crossover to do that quickly), but how do I only feed one BEC to the receiver if both escs have them? Would disconnecting the negative cable do it?

Thanks,
Steve

[RobotExtreme]

You must remove the red wire (receiver conector) of all less one ESC. Make sure to isolate the wires you removed.

[R9000]

Is this true for any and all ESC setups? Like if I had my three TZ85s all plugged into my receiver at once, would that somehow cause a problem? Does anyone else cut all red BEC wires except for one?

[RobotExtreme]

Hi,

Different of batteries that we can usually install in parallel (the voltage equalizate on both cells, energy transference) a BEC can't "transfer" the energy btwn each other. We can't say "will burn right now", but will certainly damage the RX and/or BEC. On all my TZ85 i unplug the red wire and know a lot of people that do the same. Instead you can leave all TZ85 BEC disabled (switch off) and use a external BEC.

Guilherme

[lowndsy]

Perhaps a silly question but what if I installed a little on/off switch on the red wire? Then I could turn the BEC on and off at the drop of a hat.

[R9000]

That's actually a really good idea. Nice one.

[RobotExtreme]

Lowndsy,

This would solve the problem yes.

Combat robots quality increase every year, from event to event less robots fail for "silly" issues, as a connector jump off, a switch break...

I can say that is very annoying when your robot stop during a fight and at the end you dscovery a stupid fail.

You can easily make a test, switch on a switch, hit him on a hard surface and check if he still is "on". Now imagine a robot during a fight. The best advise i can give you is, never use switchs on robots, never use bolted/spring connectors. Solder the max you can, avoid premature fails

[R9000]

To be fair, in this situation, even if the switch does break you're still fine for one fight, assuming there's one ESC without a switch. I assumed the switch deal was just so the red BEC wire that you weren't using, didn't have to be cut for good.

[RogueTwoRobots]

You don't need to physically cut the red wire. If you get a fine bladed Stanley or craft knife, you can slide the tip of the blade gently under the plastic tab on the plug of the ESC cable that locks the connector in place, then pull the red wire out. Tape up the exposed connector and tape it to the other wires. Disconnects it but keeps it intact if you need to use it again somewhere down the line.

[lowndsy]

To be fair, in this situation, even if the switch does break you're still fine for one fight, assuming there's one ESC without a switch. I assumed the switch deal was just so the red BEC wire that you weren't using, didn't have to be cut for good.

Yep, that was my reasoning too - wouldn't break anything, and I was going to use the same type of switch which is already on both of my escs, so nothing too risky. I think I'll give it a go, but no hurry while I'm sorting everything else out.