will i fry my ESC if.....

[heinie_21]

So I ran an FXR, CCBEC, 7955tg, and 3s lipo in my c2 rig for at least a year. I recently removed the FXR to switch to a different esc and noticed that on that particular ESC i forgot to remove the red wire form the plug to the RX.

My question isn't really "will i fry my esc if i dont remove the red wire?" i just used that title to lure you in here.


My question is:
"Why did I never, EVER have any issues with my high torque servo, FXR, and 3s if I had the red wire plugged in the whole year i ran that rig?"


more questions:
With the red wire still plugged in, does that mean the internal FXR BEC was powering my servo the whole time?

does that mean BOTH the IBEC and the EXBEC were powering the servo the whole time?

If i weren't running a high end RX that whole time, would the combined IBEC and EXBEC power fried my RX?



i'm perplexed. Hopefully some electronics experts can chime in

[Trubble]

Originally Posted by heinie_21

My question is:
"Why did I never, EVER have any issues with my high torque servo, FXR, and 3s if I had the red wire plugged in the whole year i ran that rig?"

(shrug) Dunno. Got lucky?

more questions:
With the red wire still plugged in, does that mean the internal FXR BEC was powering my servo the whole time?
does that mean BOTH the IBEC and the EXBEC were powering the servo the whole time?

I'd have to wonder if you never ran into problems because one of your BECs was burnt out..... or if one of them has a voltage sensor (the BEC won't turn on if voltage is already present in the circuit). Don't really know. Sadly to give you an absolutely definitive answer, you'd need to run current sensors on both red wires and see which one's actually providing current.

If i weren't running a high end RX that whole time, would the combined IBEC and EXBEC power fried my RX?

Seriously doubt it. In just about every receiver I've checked, the red pins are usually on a common bus, as are the black pins. And you'll remember from previous dissertations on parallel versus series, that if you're connecting the reds and blacks of two BECs, you will have doubled your amperage available, however your voltage should remain well within most electronics' tolerable limits. And as has also been discussed, you cannot "push" electricity, there has to be a demand for it. Even if you had a monster servo(s?) that were capable of pulling a HUGE load, in my opinion, whether or not you destroyed a receiver wouldn't be as much of an act of the BEC as much as it would how well the pins in the receiver are attached to each other. I suppose it does happen, but I've never seen a printed circuit board in an RC receiver melt off from trying to pass too much current. I'd wonder if before that happened, you start experiencing problems with the folded foil in your standard servo plug, though.

i'm perplexed. Hopefully some electronics experts can chime in

That's my quick and dirty on it. Like you said, perhaps someone can explain the science behind it all.

[heinie_21]

hmm interesting. does anybody know of a definitive thread about the lil red plug? I just wired up my FJ-Cruiser saturday with a new ESC/BEC and i'm tempted to leave the red plug in tact to see what happens. see if i get lucky twice? or if it's just a myth?

I'm NO EXPERT with electronics, but I would guess that having BOTH red wires (ESC and BEC) in tact and plugged into the RX, that it would be fine. The RX will "pull," like you said, the power that it needs. Whether it be from the ESC or the BEC.

I always compare electricity flow to water. With two red wires connected to the RX it's like having two pipes of water combining into one pipe. And the servo is at the end of the one pipe. The servo pulls water out, it doesn't care which of the two pipes the water came from because the two pipes have combined to one pipe. - i dont know whether that will make any sense, or even if it is correct.. but that's why my brain says! so i'm typing it! because that's what the internetz are for!

[Charlie-III]

I guess the first question is......what output voltage is the CC BEC set for?
If it's the same as the internal ESC BEC, that may be why you have not had an issue thus far.

Have you tried disconnecting the external BEC to see if the internal BEC still works??

[next time you turn it on...poof....they don't play together.....LOL]

[monkeyracing]

Why chance it? I've popped both red and black off my ESC lead - just run the white for signal.

[TURTLE]

Originally Posted by monkeyracing

Why chance it? I've popped both red and black off my ESC lead - just run the white for signal.

That does work some times. But often times it can lead to interference issues. You should leave the back wire going into the receiver for a return path. Even if I run the external BEC direct to the servo I still run the black wires through the receiver.

I have done it both ways before, but often when I only run the signal wire to a receiver I will suffer interference/glitching issues. It doesn't happen all the time, but most of the time it does.

[Trubble]

Originally Posted by heinie_21

i'm tempted to leave the red plug in tact to see what happens. see if i get lucky twice?

No whammies, no whammies, no whammies.......STOP!

Wanting to 'press your luck' eh? Good news is, I think the absolute worst thing that could happen is you burn out a BEC, an ESC, a receiver and a servo. As long as you've got the money to cover those, go ahead and gamble on it. Who knows, you might get lucky again and it all works. Won't know until you try.
(though my guess is you either pop the cap on your exBEC or your iBEC burns out and the rest of the ESC continues to work fine.)

Originally Posted by heinie_21

The RX will "pull," like you said, the power that it needs. Whether it be from the ESC or the BEC. .......... i dont know whether that will make any sense, or even if it is correct..

Your logic would only be correct if you ran through a diode bridge. But electricity is an insidious little monster and can get into all sorts of places you wouldn't think of.
It's been documented that it is entirely possible to get backfeed through a BEC (without a diode on the output). In this case, one BEC would 'run wide open', with power being produced going backwards through the other BEC and back to ground.
Guess you'll have to get your FJ wired up like you think it should be, and post back in here with your results.

[heinie_21]

Originally Posted by Charlie-III

I guess the first question is......what output voltage is the CC BEC set for?
If it's the same as the internal ESC BEC, that may be why you have not had an issue thus far.

Have you tried disconnecting the external BEC to see if the internal BEC still works??

[next time you turn it on...poof....they don't play together.....LOL]

It was set at factory output. I don't change them.

The bummer to all this is i can't check to see if the ibec is fried cuz i no longer have said fxr in my posession. I hope the internal bec isn't fried cuz i sold it probably a month ago as a 'perfectly working esc.' Because it was working perfectly. I havn't heard anything from the buyer so i can only assume it's still working fine. But if the ibec were fried in theory you could just always run a exbec and never have an issue, right?

Sent from my SCH-I535 using Tapatalk 2

[Charlie-III]

Originally Posted by heinie_21

It was set at factory output. I don't change them.

The bummer to all this is i can't check to see if the ibec is fried cuz i no longer have said FXR in my possession. I hope the internal BEC isn't fried cuz i sold it probably a month ago as a 'perfectly working esc.' Because it was working perfectly. I haven't heard anything from the buyer so i can only assume it's still working fine. But if the ibec were fried in theory you could just always run a exbec and never have an issue, right?

Correct.