Castle 90 ESC & Buffer Pack

[Danny_K75]

I would like to fit this capacitor-based buffer pack to my flybared trex500 running a Castle 90 ESC ( purchased 2nd hand in 2017 ).
Would I have any issues with current from the buffer packing going to the ESC or any other issues?

https://www.hely-shop.co.uk/1st-buff...-v4-8-1st9540/

[The Tok'ra]

Not sure, Do a search on Helifreak for "Castle 90 Buffer pack" see what comes back. It should be fine I suppose, the only thing that would concern me would be current feeding back through the BEC in the event of the main pack failing / disconnecting.

[trillian]

Looks like the R2 Prototyping cap pack is back under a new name.

I have a couple of the R2 units but I'm using them with Kontronik ESCs. I don't have any kind of backup device on my 500 though

[Varelco]

The BEC circuit within the ESC or the FBL/receiver unit should prevent back feeding to anywhere It shouldn't and in most cases that is true, but I can't be certain. Your best bet would be to drop Castle Creations an email.




Put it this way, whenever I set up a heli or need to check something I plug a small 4 cell NiMH into a spare port of the FBL unit so its saves the aggro of having to remove blades/back off the pinion or disconnect the motor. This has never caused an issue with my ESCs but I've never done it with a Castle Creations.

[Danny_K75]

Thanks for the info everyone.

I could only find one comment on helifreak and that indicated this was a bad idea:

the talon doesnt have back current protection like a kontronik or yge so you can send voltage back thru the talon and in turn burn it up...

https://www.helifreak.com/showthread.php?t=523986

Have emailed both Castle Creations and 1st RC to see what they say.

[Danny_K75]

I got a reply from 1st RC, gotta say that is good service!

If can work with the Catle ESC I can’t say 100%. Sorry.
But I can remember that Castle say don’t use an battery on the Receiver.
But the buffer works different to a battery.
A battery (2S Lipo) gives 8.4 volt always and goes down slowly, if you have adjust the BEC Voltage from the ESC to 7.5 volt then maybe can be damage the ESC, because the 2S Lipo has the higher voltage as the BEC Voltage.

The buffer works following:
If you start the ESC then the buffer will check the voltage from the BEC. He goes to this voltage and help the BEC only when the voltage goes down from the BEC.

That is to say the 2S battery bring always power into the ESC, but the buffer only when they need it and helps to make stable the output voltage.
I know from other Brand ESC which has an problem with an battery, but the buffers works well, with the castle I have no experience for the moment.

[The Tok'ra]

With respect, while 1st RC are correct in what they say, that's not really the problem. With some ESC's the way the BEC circuitry is designed, if the main battery pack fails, and throttle cut is not engaged straight away, the ESC will try to keep the main motor spinning and at least try to draw the required power back through the BEC leads from the buffer pack, and fry the BEC circuitry. This is not an issue if you have the option to set up telemetry data as a trigger so that when the main battery voltage drops (due to failure / disconnection) the Throttle Cut is automatically engaged. But, if you don't have that option, then it really depends on how the ESC behaves when the main pack is disconnected. i.e. does it try to keep the main motor spinning or not.

EDIT: It will be interesting to read what Castle Creations say, when they reply to your email.

[Danny_K75]

I did not know that, thanks for explaining.

What if I fitted a diode between the ESC and RX to prevent it from drawing current in that direction?

[The Tok'ra]

Yes, that would work. a big Schottky one should do the trick!

[Danny_K75]

I got a reply from Castle Creations:

"That should be totally fine as it charges to the same voltage your BEC is putting out. "

[The Tok'ra]

I got a reply from Castle Creations:

"That should be totally fine as it charges to the same voltage your BEC is putting out. "

Interesting!! I guess they are sure the ESC will not try to keep the main motor turning then. Good!!

[Danny_K75]

Some more info from Castle Creations:
"If the flight pack fails it isolates power in the ESC. It won’t send power out to the motor or back to the battery. The BEC may or may not continue to work. It just depends on how the ESC fails. "