To UBEC or Not to UBEC? That is the question.

[nasa_steve]

well I've read with interest but I always fit a separate battery for the radio AND I always disconnect the BEC if fitted to the ESC its a complete no brainer really if the aircraft can handle the extra weight and all but the smallest of aircraft can, it goes without saying.

 

i can put up with no power to the prop but no power to the radio and its no model.

steve

[Chris Bott - Moderator]

I don't think there's much in it. I like knowing my radio supply is fresh for each flight, I dont have to charge any Rx batteries or keep an eye on them.

 

When NiCads were the norm a Rx battery could just be left on trickle the night before and everything would be dandy. But Nimh's seem so variable in quality these days. e.g. higer capacity certainly doesn't mean better for our purpose.

Trickle charging can damage them but we still get trickle chargers with our radios. I'm sure there are still fliers that don't know the right way to charge a NiMh Rx battery.

 

The best Rx power source is probably a GOOD Rx battery, that is looked after, charged correctly and has a good quality switch and wiring. Sadly this is not always the case, and that goes for just as many IC models as electric ones.

[Steve W-O]

The test results are interesting and useful.

 

Looks like a combination of diode types would have less drawbacks.

 

You could also use a mosfet on the UBEC feed, with almost no voltage drop.

In fact you could use mosfets on both feeds and control when they switch.

 

It can be done simply, or not so simply, no way will be perfect, but I still think that three diodes will give a good backup, like I said at first, it has some drawbacks, but it is simple and should work without introducing more problems than it solves, after all the idea is to be able to retain control in the event of a UBEC failure, not construct a complete redundancy system. (like two switchmode UBECs fed from different batteries)

[J Moyler]

Tim,

I think that I have found what you want. CSM make a device called a BECSafe - It allow the BEC to power the model but if something goes wrong with the BEC a backup battery will kick in.

 

HERE

 

The above link should take you to the correct page. I remembered it because I was thinking about using it myself.

 

Hope you find the information helpful.

 

Regards

 

John

Edited By Tim Mackey - Administrator on 21/04/2011 18:26:58

[Tim Mackey]

John - thats exactly what I am after mate - nice find.

I have ordered one and will report back on the forum after I have tried it.

[Tim Mackey]

See here for a report on this device, page 6 - disappointing