Do I need a External uBec - RC-Monster Forums

GorillaMaxx360 · **Do I need a External uBec -** 12.02.2006, 01:23 PM

I will be runing quark 125B, 1 servo(Hitec 5995tg ti gear), 1 reciever(spektrum), (2) 2s orion 4800 (total of 4s), quark cnc machined heatsink, and one fan(40mm 5v 5500 rpm). My question is do i need a ubec. Some people have told me that i need one, but when i looked at the bec information on rc monster i says you only need one if your exceding cell amount or servo amount. Now as far as i know i am not exceeding either because quark can go up to 5s and like more than one servo(i think) so do i realy need a ubec(external) for safe/efficient running. Thanks for opinions

danverz · 12.02.2006, 01:41 PM

Hi,
I think yes, you need at least for 3 reasons:

- using an external BEC helps your controller to get not hot
- that servo you are using can peak over 3.5 Ampere and this is a lot for an internal ESC Bec
- using an external bec means you will have a lot less spurious current coming from
the Esc and going to the receiver ... this usually means less interference.

Ciao,
Daniele

neweuser · 12.02.2006, 01:50 PM

A ubec is recommended, it will help keep your esc cooler.

BrianG · 12.02.2006, 02:09 PM

BEC & Wiring Info

GorillaMaxx360 · 12.02.2006, 02:57 PM

Thanks a ton i have ben looking for something like this. I love it nice!!!!!!! :004: :004: :004: THANKS A TON

BrianG · 12.02.2006, 03:09 PM

NP! That's what it was made for. :)

GorillaMaxx360 · 12.03.2006, 12:12 AM

So when i get this ubec is there any keep up work(bad word choice) to do after i install it like charging it or something or pretty much when it is installed i need not do nothing more.

BrianG · 12.03.2006, 12:22 AM

Nope. It pretty much starts working immediately after connecting the main batteries. Follow the diagram on my wiring page and that's it.

GorillaMaxx360 · 12.03.2006, 12:25 AM

cool

coolhandcountry · 12.03.2006, 10:38 AM

I don't think the quark is recommended to use internal bec on over 3s lipo.
Some one had a melt down on 4s lipo with bec. I would go with external ubec.

12.13.2006, 12:17 AM

...BG that is a FANTASTIC page...Really helpful...Thanks for the obvious time you have spent on it...REALLY good...

jhautz · 12.13.2006, 12:56 AM

This is what happens if you don't disconnect the internal BEC above 10 cells.:eek:

I didn't even run it. This is just sitting on the bench with 5s plugged in. Everything still works fine, but if I didn't notice right away that it was getting hot, who knows.... Ive been using it a good 8 months like this now.

BrianG · 12.13.2006, 10:15 AM

Thanks BitHed! I did some searching around and found there were a lot of explanations and diagrams, just nothing in one place. So, I came up with a single place to go to.

jhautz: Wow, that looks like it got quite hot indeed! Although, the regulator will get just as hot on a bench as it does running, probably more so since there is no airflow. Even at a 1A load, the regulator will have to dissipate 16w @5s. That's a lot. Now that you know where the IC is, you couldcut away that part of the plastic and mount a heatsink on it. :)

I'm wondering why these would actually burn up though. Most linear regulator ICs have a thermal and current overload sensor and simply shut down. Maybe it just happens too quickly for these circuits to respond.

Basically, if you even think you might need a UBEC, get one. At worst, it will be a waste of a few bucks. At best, it'll run much more efficiently.

I don't know if anyone noticed on my BEC calculator page, but a UBEC actually increases runtime over the built-in one. Since a UBEC is really a powerIn=powerOut device, the draw from the main batteries is lower than the BEC load current, especially at higher cell counts. While a built-in BEC pulls the same current from the main batteries as BEC load current. Just thought I'd point that out. :)