BEC Melted Wires

[fastbaja5b]

Ok this has me puzzled.

Savage Flux with a Hobbywing 150A Esc Turnigy HV767 Servo and Spektrum RX, 4s Lipo set up. I hooked up the ESC to the receiver, with an extension lead with the red wire missing and then hooked up the BEC using one of these

http://www.hobbyking.com/hobbyking/s...r_adapter.html

between the Deans of the Lipo and ESC on one side. (ESC has dual Deans in a Series configuration like the Savage Flux Set Up does on the stock esc)

With the JST end plugged into the input wires of this BEC
http://www.hobbyking.com/hobbyking/s...ly_6_23v_.html

And the output connected to the Battery socket on my Spektrum Receiver.

Plugged everything in, RX has power, Servo moves fine, as soon as I turn on the ESC however, the wires between the BEC and Receiver melted as did the Servo Extension with the red wire missing between the ESC and RX

So I removed the adapter, extension and BEC, hooked up the ESC directly (using internal BEC obviously) and everything was fine.


....so what gives?

Any clues as I'm puzzled on this one!

[brainanator]

You melted the red wire on the extension that isn't even connected?

[fastbaja5b]

No I remove the Red wire from the servo extension entirely, the Black and White wires melted.

[_paralyzed_]

As wire length increases so does resistance, as resistance increases so does the temp.

But I don't think that was the problem

It sounds like a faulty bec to me. Do you have a voltmeter to determine the actual output voltage of the bec?

This is a weird one alright. You obviously had more current than the wires could handle, but that shouldn't have melted the extension to the bec.

I don't fully understand why you chose an hv servo if you were only going to send it 6v anyway? Were you just using a bec to lighten the load on the esc?

Perhaps it was a combination of too long of an extension and a faulty bec and both failures occurred simultaneously?

[fastbaja5b]

The servo was just one I had in the box which they state runs fine on 6V as well as 7.2V

http://www.hobbyking.com/hobbyking/s...idProduct=9983

The ESC internal bec seems fine with it, and thats without a Voltage Cap which I usually run on my Spektrum gear

[_paralyzed_]

Originally Posted by fastbaja5b

The servo was just one I had in the box which they state runs fine on 6V as well as 7.2V

http://www.hobbyking.com/hobbyking/s...idProduct=9983

The ESC internal bec seems fine with it, and thats without a Voltage Cap which I usually run on my Spektrum gear

It's gotta be the bec but I can't wrap my head around why it happened when you turned your esc on. Gremlins?

[suicideneil]

Which battery did you connect the BEC to, via the in-line adaptor?



It should have been wired up like-so^, paying close attention to where the BEC input wires are going exactly ( which battery & wires ).

[fastbaja5b]

Yeah it was connected as a deans adapter between the harness and one of the Lipos at the battery end

[Arct1k]

Which Lipo? You MUST connect it to the ground side lipo otherwise you had a floating voltage issue.

Ground on BEC is actualy 7.4v to the ESC. Guessing this is were it got f'd up.

[fastbaja5b]

Ok I will double check that, if that's the case where I hooked it to the wrong battery (ie positive from batt not neg from batt) then it's easier to swallow

...but the BEC is rated 2-5s Lipo?

[Arct1k]

It's more that the esc ground is 0v but the bec ground is 7.4. Effectively creating a short.

[fastbaja5b]

...and we have a winner! It was plugged into the + side pack not the neg side pack

[Arct1k]

That will do it :)