CC BEC turning itself off

[ik632]

In my Wraith I'm running a more beefy servo than stock so have a CC BEC wired so it bypasses the receiver for power. Basically, I have ground and signal going to receiver and then using the bypass harness sending power to servo (it's the same setup I use in my XR10).

Anyway, I have the BEC zip tied to the tube frame of the Wraith to keep it out of the way and it's turned itself off a few times (which I have no idea how it could do that). It's certainly not getting wet or hot.

Here's what happens:

1. Drive around for about 20 minutes on a 5000mah 40c 2s pack
2. all of a sudden steering stops working but truck goes forward/back just fine
3. unplug battery (BEC is wired to leads on ESC power)
4. plug battery back in and BEC turns back on

So, it seems a bit weird, but basically the light on the BEC turns off, then when you unplug it and plug it back in it works again. BEC is only about a month old and has about 5 or 6 runs on it so I'm wondering if it's bad from the factory.

[OhioCrawler]

Is your battery voltage getting below what you bec is programmed to? I was bench testing something last night and mine was doin the same, realized my "test" battery dropped below the bec output and turned itself off, i unplugged twice and replugged in and it turned back on for a few secs until i realized what was happening. Caught me off guard for a sec. Something to check...

[ik632]

Ohio,

That's a good point. My BEC voltage was set to 7.0v for my Hitec servo. I hadn't hit LVC yet (which I think I have set to 7.0v manually because I have an AE-2 and it's LVC isn't very reliable). The weird part is when I unplugged and plugged it back in it ran for another 20 minutes without any issue.

So, if I am getting to that voltage (where my battery is below the output of the BEC) should it be turning itself off or should it just supply whatever voltage it has available?

[ik632]

From Castle Manual:

Low Input Voltage
In the event that the input voltage falls below the desired output
voltage, the CC BEC output is essentially equal to the input level.
CC BEC cannot output more voltage than the battery it draws from.
The CC BEC will not operate or produce any output when input voltage
drops below 4.0 volts.

So, it shouldn't turn itself off I'm guessing.

[OhioCrawler]

Originally Posted by ik632

From Castle Manual:

Low Input Voltage
In the event that the input voltage falls below the desired output
voltage, the CC BEC output is essentially equal to the input level.
CC BEC cannot output more voltage than the battery it draws from.
The CC BEC will not operate or produce any output when input voltage
drops below 4.0 volts.

So, it shouldn't turn itself off I'm guessing.

Good call on that above info. It is weird though. Cause mine was honestly doing it last night, and when i grabbed a fresh battery i never had another issue.

BUT now that i think about it i use an old 7.4v battery, so in my case maybe it did drop below the 4v bev cutoff using my old "bench" battery


Sorry i couldnt help...

[Charlie-III]

ik......maybe you had a large load on the motor/servo which dipped the battery voltage enough to stop the BEC. After you unplugged/plugged you never loaded it enough to do it again.

Does your CC BEC have a "large black can" sticking out the shrink wrap? If so, it's the newer version.

[ik632]

Not sure, I'll need to check when I get home. I know the one in my XR has a capacitor sticking out the end where the power leads go in. Not sure if the one in my Wraith has it.

It may have gotten loaded, but the spot where it kicked out was going down a slight hill then taking a left around the garden. I do wonder now, if the servo arm got bent and was rubbing against the diff cover. I'll need to check that too. That could certainly run the amperage way up and brown out the system.

[ik632]

I'm guessing the "newer" model with the big cap doesn't brown out as frequently. If so, I'm ok soldering a larger one in place.