sorry, but BEC questions on 9920, also want to confirm wiring! - RC-Monster Forums

R00ST · 02:55 AM

Alright I did a search and saw some old threads simliar to my questions, but I just want to get a confirmation on a couple of things (cant risk burning up these new electronics!!!)

First off: I am running 14 cells on my 9920/8xl. I do have two 5 cell receiver packs, but would prefer not to use them. I do plan to order a UBEC once I return from our vacation (spending two weeks in FL, the revo is coming along :) ) so until I can get my hands on a UBEC, can I safely run the internal BEC? And if the answer to that question is yes, I shouldnt have to pull the black jumper, right? (just leave everything how it came and bec is enabled correct?)

My other question was to wiring. I am wondering the best way to wire this up using deans plugs.

This is golf's drawing by the way, was in his thread (want to give credit where credit is due!)

Is the above drawing correct for my application (obviously minus the extra + and - wires coming out of the controller)

Sorry for the nubish type questions, I am just fretting plugging this thing in for the first time, as I CANNOT afford to fry anything!

Thanks everybody :)

Serum · 12.24.2005, 04:36 AM

On 14 cells, the internal BEC should be fine. I personally prefer a UBEC though. it's more stable.

Removing the black jumper is the thing to do to disable the internal BEC. keep it on, as long as you don't have got the UBEC or external receiver pack on.

Using deans plugs makes this drawing very usefull. This is the way to do it.

You are on a roll, You got the idea.

coolhandcountry · 12.24.2005, 08:53 AM

On the internal bec. I have ran it with 14 cells on the older controllers. It worked but it had issuses. Nothing to worry about really. It would quit working until you unplugged the esc and plugged it back up. So if you have this problem don't worry just get the receiver pack out. :D

Sylvester · 12.24.2005, 11:05 AM

What about for 16 cells, would i need a bec?

MetalMan · 12.24.2005, 01:40 PM

Yes. The voltage regulator on the 9920 (BEC) has to burn off the extra voltage to bring it down to 6V (or whatever voltage it is at). Then, the more amps that are pulled, the more amps that are put into heat. The equation for how many watts are into heat is (Vin-Vout) x amps. So, 16 cells are about 19.2v, and the BEC voltage is about 6v. That's a voltage difference of 13.2v. A high torque servo can easily pull 1amp continuous, and 2amp peaks (or even more). That would be 19.2watts continuous, and that's a lot of heat even for a chip with a heatsink! But, the BEC chip on the Warriors doesn't touch a heatsink, so it is best to keep the voltage low.

Serum · 12.24.2005, 02:21 PM

Yeah, on 16 cells a ubec is wise to use.

R00ST · 12.24.2005, 02:46 PM

I think I will just try my luck with the 14 cels, and bring along the two receiver packs we have left over that came stock on the revos just in case the controller heats up, or gets finnicky on me.

This forum is a life saver! I am proud to say this is the only rc forum I really visit anymore (sometimes go to traxxas to look up old threads)

Hope everyone is enjoying the holidays! I know my christmas spirit will really kick in when I get to thrash this truck for the first time (merry xmas to me :) )