Bec confusion

[Steve g]

I recently bought a cheapo hobbywing bec to help relieve some strain on my ae5 esc. I wired it in and when I turn all the way to either side and let off the steering rapidly, it will jerk the truck forward like I hit the throttle for a split second. I mounted the bec as far away from the receiver as possible, as per the instructions in relation of interference. Now the odd part is for the hell of it I hooked the red wire back into my receiver from the ae5 built in bec, and the issue went away. I didn't drive much like this, because I've read it's bad. So wtf is the issue here? I have proper voltage from the hobbywing bec, even tried another hobbywing bec as I bought a 2 pack for the price. How bad is it to have the hobbywing bec and the ae5 bec plugged in together? And why does that fix the problem? And what is causing the problem?

[DavidH]

It is bad to have two regulated power supplies trying to regulate the voltage on the same circuit. I expect that the power supply with the weakest components will let go of its smoke.

Without seeing how it is wired I could only guess at the problem. Check your voltage at the esc at idle and under load, even if you have to wire in some test points.

[Greatscott]

Originally Posted by Steve g

I recently bought a cheapo hobbywing bec to help relieve some strain on my ae5 esc.

I think this statement pretty much nailed what happened.

I would put a multimeter on to the BEC's output and testing it static and under a load, more than likely when it is actually trying to supply power to something the voltage isn't stable.

Also, what is the voltage of the ESC, and what is the voltage of the HW BEC? What is the amperage rating of each?

[TooOldForThis]

I run one of those same cheapo hobbywing BEC's with excellent results. If both BECs are giving you the same symptoms, this is much more likely a wiring issue.

This thread may help you: Separated power for the servo

It's about running a servo directly off a battery, but it can be applied to a BEC.

[Steve g]

Last night i by rewired my hw bec to power only the servo, and it solved the issue. But I just put it back how I had it to test the voltage as you guys recommended. So my esc has an output of 5v and 2a for the bec. I didn't check this with a meter. The hw one is 6v 3a. Not much improvement, but my servo is about 300 or 320 once at 6v. So I did check the voltage of the hw bec, 6.1, from both actually. Then under load, still 6.1v. Even when it spun the wheels. My meter may not be sensitive enough to catch the voltage rise or drop when it sends a bad signal or whatever it's doing. It's a fraction of a second, so might not be reading it. I wired it as follows: bec power leads soldered to battery connector off of esc. Bec plugged into receiver. Red wire from esc bec disconnected and taped off. All I can think of is my servo is sending interference through the system when I let off the steering knob, and for some unknown reason it only effects the receiver when the hw bec is being used. It's a cheapo powerhd servo. Seems to be holding up well though. Even though my problem is resolved, I still would like to know what happened and why. Electronics are finicky and can be unpredictable I guess

[mewalsh100]

It sounds like you have it all wired up properly. As far as interference, I was fearful of that too when I was building my new Truggy this past november. I had very limited realestate to work with to mount the esc, bec, and rx. After searching around on the internet and posting my concerns here, I was told it was a non issue. The frequencies modern Tx/Rx operate are not really affected. To that end, I have my esc, bec and Rx all packaged right together on a small mounting plate I fabricated. I have had zero issues with glitching/interference.

Maybe it’s just the cheapo BEC? That said, a 10amp Castle is only like $18.

[nightcrawler48]

Originally Posted by Steve g

Last night i by rewired my hw bec to power only the servo, and it solved the issue. But I just put it back how I had it to test the voltage as you guys recommended. So my esc has an output of 5v and 2a for the bec. I didn't check this with a meter. The hw one is 6v 3a. Not much improvement, but my servo is about 300 or 320 once at 6v. So I did check the voltage of the hw bec, 6.1, from both actually. Then under load, still 6.1v. Even when it spun the wheels. My meter may not be sensitive enough to catch the voltage rise or drop when it sends a bad signal or whatever it's doing. It's a fraction of a second, so might not be reading it. I wired it as follows: bec power leads soldered to battery connector off of esc. Bec plugged into receiver. Red wire from esc bec disconnected and taped off. All I can think of is my servo is sending interference through the system when I let off the steering knob, and for some unknown reason it only effects the receiver when the hw bec is being used. It's a cheapo powerhd servo. Seems to be holding up well though. Even though my problem is resolved, I still would like to know what happened and why. Electronics are finicky and can be unpredictable I guess

I run Hobbywing BECs on all my rigs, actually 2 on rigs with lights. I have had no issues and been doing this for about 3 years.

The difference is, I leave the red wire on the plug from the ESC to the receiver connected to provide the power to the receiver. The BECs are soldered to the battery connector so as soon as the battery is connected the BECs have power. The output wire from the BEC is connected directly to the servo and the white wire (signal) is the only wire going to the ESC.

Don't know if the picture helps. This isn't exactly what I finally end up with, just components to bench test as I go along.

Hope this isn't too confusing.

One last thing, some people run 2 ground wires from the servo, one going back to the BEC and another plugged in with the white wire to the receiver. I've never had an issue with just the white wire connected to the receiver.

[Hydrocarbon92]

Without a picture or actual diagram it could be described as wired correct but not.

The servo's BEC should not power the receiver, leave the ESC's BEC to power the receiver. It sounds like the receiver is browning out when you're powering both the servo and receiver from the same BEC. The receiver will only use a fraction of an amp, and it doesn't benefit from extra voltage - just clean voltage.

Regarding a single ground, it can work if your grounding is done right. When it's done wrong or the electronics it passes thru aren't ideal, you can get voltage offsets & noise. IMO the risk is not worth 1 less wire.

[Steve g]

Yeah I have it now powering just the servo. Almost like the picture there but one less connection, and the double ground. At first I had it connected as I wrote of in the previous thread, and that's when it gave me issues. The hw must just have interference that my receiver can't handle. Any of you who have the hw one ever use it to power the reciver as well? I don't know the brand of my reciever, trucks back together. It's an oem wraith spawn, so probably a tactic?

[Hydrocarbon92]

First you need to answer if it's a genuine Hobbywing. If it was less than $7 and the company isn't an approved reseller, it's probably a clone. If so, it might have really weak components - not enough for 5A peak. If that's the case, your receiver's voltage will drop low enough to reset it. A resetting receiver can do all sorts of unusual things during a brown-out.

Either power the receiver separately with the ESC's internal BEC, or buy a 2nd clone HW BEC and power it separate from the servo. There is no free lunch with BEC's, either multiple cheap BEC's or one expensive BEC (Castle 10A, HW 20A, etc).