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Need a new BEC
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Shimmy
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Need a new BEC - 07.05.2011, 04:42 AM

Hey fellas,

Well I fried my CC BEC (10a) running a Savox 1268 the other day, so I am in need of another, a better one.

I don't particularly fancy buying another CC one, but I cannot find anything else that can take a 6s lipo and put out 7.4v.

I also don't fancy the idea of buying a BEC that costs the same as (or even have as much) the servo.
I would rather sell it and buy a 6v one and be done with it.

I do have another idea though, I have made up a plug that I could put on the balance plug of my 6s lipos to use just 2 cells to power it.
Obviously not the best way as it would be draining 2 cells slight more than the rest.

Cheers.
   
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simplechamp
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07.05.2011, 08:20 PM

What were the circumstances of the failure? How did it happen?

For the price and specs I think you'll have a hard time finding anything better than the CC BEC. There's the CC BEC Pro, but the regular CC BEC should be plenty capable of handling that servo (as long as it's functioning properly), and you said you aren't keen on spending $40+ on a BEC.

Have you been able to test the servo since the BEC fried? Possible the servo is at fault? If you know the servo is functioning properly I'd have to chalk it up to a random fluke failure of some component in the BEC.


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Shimmy
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07.06.2011, 12:13 AM

I was on a grassy area, it was a little wet but the BEC (and everything else) was bone dry, so I am about 99.99999999% sure it was not a failure due to water.

No excess load or anything, just driving it about, it died in a straight line, I went to turn and had no steering.

I have always found it to run hot, even with the last servo I had in it.

I have hooked up the servo directly to a 2s lipo (got confirmation from Savox that it will run on 2s directly) and it seems to work fine.

There is no binding in the steering, it's all nice and free.


I am willing to spend $40, it's just that I kinda find it hard to justify when there are plenty of quality $50 servos out there that could do the job, although with another Savox one, I would probably need a BEC anyway.
I did have a Hyperion DS20 FMD running in it for a short while which did the job well.

I mainly got this servo to be the end of all servo problems, not thinking that it would cause me more problems.

EDIT; I just took a picture of it and looking at I think theres a possibility that it shorted out.
I am assuming that the film stuff all over it is their water prevention stuff.
Looking at the bottom legs of that chip, it's obvious that the one on the right is near non-existent, the others look like they had something across them but dunno what.


Last edited by Shimmy; 07.06.2011 at 12:27 AM.
   
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Arct1k
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07.06.2011, 02:21 AM

Consider castle will send you a new one for the cost of postage (pretty much) just send it in
   
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Shimmy
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07.06.2011, 02:51 AM

I am in Australia, for the cost to send it back it would probably be cheaper to just buy a new one.
   
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BrianG
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07.06.2011, 11:25 AM

I would just get a new BEC. It does look like the chip (primary FET driver?) and other components are toast. To be clear: the servo still works right? Because when a bec fails it can send full input battery voltage to your servo and rx possibly frying them as well. Hooking a new bec to fried components can result in frying the new bec.

Yeah, I wouldn't suggest using voltage off the balance taps for the reason you said. Either get a new bec or use a seperate 2s lipo/life.
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Shimmy
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07.06.2011, 12:43 PM

Yeah, I was thinking of just getting another BEC.

As for the servo itself...
It was working.

I had it hooked up to a near flat lipo the other day and it seemed to work fine (unloaded)

After getting an email from Savox themselves confirming that these servos CAN run on 8.4v, I just tried it again with some load (installed it back in the truggy) and it turned one way then stopped working.

I pulled the case off and had a look over it, the solder around the motor has turned into 2 big pools...

So... I ain't buying any more high end electrics, just not worth it for failures.
$20+ to send it back + $whatever they charge to fix it + $20 for them to send it back, and thats if they even take it (I bought it from RC Mart).
I may aswell just use cheap stuff.
   
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lincpimp
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07.06.2011, 02:41 PM

That sucks... Good thing you tested the servo before you put a new bec in...

Seems like a 2s capable servo running off a 2s lipo would be the best bet. And run the rx off the internal bec in the speed control.

Now you would have to correctly size the servo lipo so that it will not go below 2v per cell during the run, and you would have to charge it...

Someone needs to make a bec that will not send full voltage thru itself if/when it fails... Maybe I am asking too much? I do remember pdel commenting on this a while back but cannot remember what conculsion was reached.

How about this:

Say you are running a 6s setup. And you want X mah for the lipo.

Figure out the average servo draw (Y)

So get a 4s lipo with X mah, and a 2s lipo with X+Y mah, and hook the servo to the 2s pack via the balance tap or other wires off the main leads.

That way the sevo will use the extra capacity in the 2s pack.
   
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