What is a UBEC and do I need one?

[Coyote]

I recently purchased a model (Dynam T-28) that has retracts and has a total of 9 - that's right - nine servos.

While researching tips on the model build, one of the topics that came up was the BEC (battery eliminator circuit) in the stock 30A ESC was not up to par to handle all servos and receiver in case of low voltage or ESC reset. The solution - a UBEC(universal battery eliminator circuit)!

Now, what is a UBEC and do I need one?

Answer is attached (found it on the net) - hope it helps you as much as it did me

PS: I wonder if Brian's B-17 is equipped with a UBEC?

[RocketManRC]

You can also use a separate receiver battery Marc. I make my own from 4 AA NIMH rechargeables.

Due to problems in the past that could not be explained, I started using either a battery or a UBEC when I have 4 or more servos and always for helis. The only exception I have made is with the Castle Creations Phoenix ICE ESC that is in my 450 heli.

A word of caution however. I recently had a Turnigy UBEC fail after about 2 years of use. Unfortunately it's failure mode was to pass the full battery voltage to the output and fried all the electronics. I have since switched to using the Castle CC-BEC in anything that I value. It is not cheap but neither are the models I put it in.

Rick

[retiredVTT]

Just a reminder...if you do a "search" on the HEFA "RC UNIVERSITY" forum...several additional posts with links concerning UBEC's pop right up.

This is the very reason why this "library of info" was conceived.....

cheers,

Bill

[saboo]

RockeTMan's failure is possibly more a ground loop issue which will fry the electronics by having the full motor current go through the plugged in devices. May not be but depending on the wiring it could be.

For instance if you use a BEC separate from the one in the ESC the ONLY connection from the ESC to the Rx should be the signal line. NO ground, NO positive. The ground and positive are coming from the battery feeds / leads directly. The ground and positive for the Rx are coming from the BEC. The ground and positive for the ESC and the BEC are tied together at the battery 'Y' connector.

Now when there is any problem the ground ONLY goes back from the ESC to the battery via the heavy battery feed/lead, not via the 22 or 26 gauge ground wire from the ESC to the Rx. This ground loop condition will fry virtually all electronics it passes through as it could be full battery voltage of 10+ volts going through 5 volt rated devices.

I read a detailed account with examples on RCG about ground loops and it was very enlightening. I found potential ground loop conditions in my TwinStar and modified the wiring appropriately. If I can find it again I will post the link. Later - After a quick search I was unable to find it.

So a careful examination of the problem with Rick's unit may reveal the existence of a ground loop which could have contributed to or caused the failure. If not the direct cause, a ground loop could then have applied full pack voltage to the electronics when one component failed.

Saboo

[Dirt Torpedo]

?

[RocketManRC]

There was a lot of discussion in the MultiWiiCopter forum last winter about removing the ground paths from multiple ESCs as there are many ground connections in the case of a multicopter. The end result was inconclusive I would have to say and mostly related to noise problems, not failures.

But anyway Marc you do need a UBEC or a battery for your application and you need to remove at least the red wire from your ESC connection to your receiver when you do that.

BTW I have a couple of slightly used Turnigy UBECs for sale real cheap. Just kidding

Rick

[retiredVTT]

...and a good way of eliminating that red wire from your esc is to use a nice little 4 inch extension lead and cut the red wire in it...that way you don't butcher your esc which you may want to reuse in future in a non UBEC circuit..!

Bill

[AndrewS]

Another alternative to cutting the red wire is to use a Dimension Engineering BEC.
They are designed such that the red wire does not pass to the receiver, so all you have to do is plug the ESC into it and plug it into the receiver. John has/ had some on the wall at Maritime.
Andrew

[RocketManRC]

I have a couple of those as well and they do a good job. But I don't think they will handle the 9 servo setup!

Rick

[steve]

9 servos.....?

What kind of superfantastic Mugi are you building ?

lol

Steve