remove red wire?

[lydiasdad]

Does removing the red wire actually turn off the esc's bec or does it just remove the load?

[BrianG]

Just removes the load.

[lydiasdad]

That's what I thought. I did this in a tekin 420 g2 and the bec heatsink still got hot. I noticed that you can leave the red wire attached and just leave the esc's switch off and then the bec does not seem to heat up. Is there any harm in doing this?

[Finnster]

wha?

Couldn't you say its turning it off by removing the load? No diff than having a switch inline right?

That last part doesn't make sense. Would you expect the esc to heat up when its switched off? Truck doesn't go too fast tho. ;)

Either way, remove or cut red wire. BEC is disabled and ESC is happy.
Must be my reading again...

[BrianG]

An ESC's BEC not only powers the receiver and servos, but it's own low-level circuitry (brains). When you unhook the red wire, it simply keeps the BEC from powering any external devices, but is still running to power its own circuits. The BEC chip should not get hot at all if the red wire is removed, since the ESC internal circuits are low-power.

Also, the heatsink in most ESCs I've seen are not attached to the BEC circuit at all, so any heat generated is usually wicked away using the PCB traces. Maybe some of that heat is making its way through the traces to the FET board, to the FETs, and then to the heatsink, but that's indirect at best.

The Tekin might be set up differently though - what I said above applied to the MM, Quark, and BK Warriors.

I do know that at anything above 2s/6 cells, the internal BEC can heat up quite rapidly. So, if running 2s/6 cell, I'd use the internal BEC. If anything 3s or higher, I'd use a switching BEC...

[lydiasdad]

Originally Posted by Finnster

wha?

Couldn't you say its turning it off by removing the load? No diff than having a switch inline right?

That last part doesn't make sense. Would you expect the esc to heat up when its switched off? Truck doesn't go too fast tho. ;)

Either way, remove or cut red wire. BEC is disabled and ESC is happy.
Must be my reading again...

When you leave the red wire in the esc plug, and plug the reciever pack in the reciever, the esc turns on as if it's circuits are being powered by the reciever pack. The esc works fine as far as I can tell, no problems yet and the bec heatsink is cool. That is with the esc's power switch in the off position. The tekin 420 does have a seperate heatsink just for the bec. This esc can handle 24 volts and the manual says to use the heatsink on the bec if using over a certain voltage.
I am sure not all esc's are this way.
Wouldn't a bec have to dissapate a lot of heat when stepping down such a large voltage, even if there is no load?

[BrianG]

Originally Posted by lydiasdad

When you leave the red wire in the esc plug, and plug the reciever pack in the reciever, the esc turns on as if it's circuits are being powered by the reciever pack. The esc works fine as far as I can tell, no problems yet and the bec heatsink is cool. That is with the esc's power switch in the off position. The tekin 420 does have a seperate heatsink just for the bec. This esc can handle 24 volts and the manual says to use the heatsink on the bec if using over a certain voltage.
I am sure not all esc's are this way.
Wouldn't a bec have to dissapate a lot of heat when stepping down such a large voltage, even if there is no load?

Yes, plugging in a Rx pack will power the whole unit if the red wire is intact, sometimes even the BL motor! Most designs using linear regulators use a diode from output to input to prevent issues if the output voltage is higher than the input voltage. So, this allows the Rx pack to feed all the circuits.

Having a dedicated heatsink for the BEC is a good idea. Nice job tekin!

You need a voltage difference and current to generate heat in a BEC. The heat wasted can be expressed as W = (Vin - Vout) * Aout. So, even if you have 30v, if there is no current, there is no wasted power: (30v-6v) * 0A. If the ESC itself only draws 50mA, the power loss is pretty small. It's those dang servos that can draw the current, which causes a linear BEC to be so inefficient.

[Topspeedtimmy]

What happens if you leave the ESC switched on and still use a reciever pack?

[BrianG]

You'll drain the batteries over time because there is some "leakage" current.

But, I think you meant "What happens if you leave the BEC switched on and still use a reciever pack?"? Well, that depends on the regulator. Since a receiver pack is typically at higher voltage than a BEC, the receiver pack should take the load. Once the receiver pack voltage falls below the BEC voltage, the BEC takes over (in fact, the BEC would be charging the Rx pack at this point). This assumes that the regulator is designed how I think it is. If it's not, hooking a Rx pack and the BEC could potentially damage the BEC.

[Topspeedtimmy]

How do you turn off the BEC, just take out the red wire from the ESC?

[bdebde]

Originally Posted by Topspeedtimmy

How do you turn off the BEC, just take out the red wire from the ESC?

That's it.

[Matthew_Armeni]

Aren't Novak's wired a little differently? I remeber reading in their instructions for their HV Maxx controller that if you run a single pack (like a 12v or a 4s) you can't turn on the ESC when you run it, otherwise you'll burn up the ESC. You have to run an external ESC or rx pack. Never mentioned unplugging the red wire, although I'm assuming that this would work too.

[lydiasdad]

Originally Posted by Topspeedtimmy

How do you turn off the BEC, just take out the red wire from the ESC?

No that does not turn the BEC off, it only removes the load from the BEC.

[Topspeedtimmy]

And that's okay, right?

[lydiasdad]

I guess thats all you can do. Thats kind of why I started the thread. I was hoping that there was a way to actually turn off the BEC and power the ESC circuits with the receiver pack or UBEC.