Castle BEC Update

[Arct1k]

Anyone else noticed that the newer ones now have a cap installed on the input 20uf?

Suprised to see that its only rated for 25V though.

On 6s I'd think it would be close to limit with voltage from braking...

[BrianG]

Not to mention 6s is 25.2v fresh off the charger...

I noticed they have. A capacitor. On them now they work better too

I got couple of them just recently. I thought they were old stock or something as I didn't hear anything about an upgrade to them.

Anyway what is the point of the cap on them. To me it looks like it is on the input side. I could understand if it was on the output side to help level out the voltage but have no idea why have one on the input where there really shouldn't be a dip in voltage bellow 6V. Maybe I am missing something so if someone could explain it I would very much appreciate it.

Also I can't see a difference in operation with the cap version compared to one with out it. Both seem to hold voltage just as well with similar HV servos.

[padrino]

Originally Posted by BIG-block

I got couple of them just recently. I thought they were old stock or something as I didn't hear anything about an upgrade to them.

Anyway what is the point of the cap on them. To me it looks like it is on the input side. I could understand if it was on the output side to help level out the voltage but have no idea why have one on the input where there really shouldn't be a dip in voltage bellow 6V. Maybe I am missing something so if someone could explain it I would very much appreciate it.

Also I can't see a difference in operation with the cap version compared to one with out it. Both seem to hold voltage just as well with similar HV servos.

If using the BEC with a main battery I could see cases where lower quality batteries would stave it some under high current draw (acceleration), I assume it was added because of a specific problem in the field that has resulted in issues/crashes.

[BrianG]

The input cap is probably to help cope with ripple currents. The motor/ESC is generating the ripple, but it is also present on the BEC wires as well. Couple that with the longish BEC input wires may cause undesired BEC operation in the switching circuit.

Originally Posted by BrianG

The input cap is probably to help cope with ripple currents. The motor/ESC is generating the ripple, but it is also present on the BEC wires as well. Couple that with the longish BEC input wires may cause undesired BEC operation in the switching circuit.

Cool. Thanks for that Brian. I kind of figured that input voltage being so much higher than whats going out isn't going to be troubled too much by ripple currents but I can see what you are saying. The jest of it is it just gives the BEC a smoother voltage to work with. Right?

Anyway both versions work just fine in my applications. They are mainly all powering just a steering servo except one that is also powering 8 LED's as well. 4 of the older ones and 2 new version seem to work just fine.

Early on I was warned about using CC BEC. I was told to use Dimensions Engineering BEC instead because the CC switching BEC could possibly send full battery voltage to my servo/Rx in case of a failure. Well two years later they are all kicking butt. Also considering they are only $20 and so easy to adjust voltage output I will not use anything else. I will have to get the Pro version soon because for my XL. Hopefully it will also be trouble free as the smaller ones.

[BrianG]

FYI: ALL switching "bucking" regulators can potentially send full battery voltage to the output. They all have a FET in between the input and output that switches and provides (along with the output coil, Schottky diode, and cap) the step-down action. If that FET decides to fail by internally shorting, then there is nothing to limit the input voltage from making its way to the output.

[suicideneil]

Other than that little invention of yours that you designed a while back as an add-on failsafe of sorts...