Hitec HS-7950TH servos CC BEC PRO no 7.4v setting

[indiana mudcat]

the cc bec has a 7.4 setting, but he's using the 20amp cc bec pro, it might not I have no idea.

I wouldn't think he would have the voltage drop enough to shut the rx down with the 20 amp unit, but it might pass some extra heat through it if all were ran through the rx.

 

[deephis46]

upss...sorry my bad
cc bec pro has limited info but i just saw this
http://www.castlecreations.com/media/press-releases/pr-ccbecpro.pdf
they said that '1/10th increments' for ccbec pro too CMIIW

 

[Lushtrucker]

the cc bec pro has .1v increments up to 7v, then jumps to 7.5v. I don't know why castle did it that way.
I talked to a castle tech about wiring the pro with 1 of the wires to the servo and 1 to the rx since it has two leads, he stated that there would be a concern with the bec seeing different grounds and possible feedback or failure. It is best to have both plugged into the rx, you can use a y harness if you don't have a 2nd plug available.
He also stated that the pins in a standard servo plug are only rated for about 5A, which is why they put two power wires on the pro.

as others have said, the spektrum rx's are rated up to 9.6V and hitec claims you can run the servo off of a 2s LiPo which will put out 8.4V fully charged. I see no issue with running it at 7.5V if you feel you need the extra power over running it at 7V

 

[Irishchamp]

so the issue is having one of the BEC Pro plugs going to the RX and the other split between the RX and Servo? what if both plugs on the BEC Pro were going to two servos, that way no discrepancy in ground signal? if the RX can receive and supply 5 amps per pin connector is that peak or continuous? if thats peak then I would basically be downgrading my BEC Pro to a standard CC BEC with a 10 amp peak rating. if its continuous then maybe it would allow the whole 20 peak amps through from the BEC Pro. The RX can then just receive power from the BR-XL's on board BEC instead of disconnecting the red wire.

the cc bec pro has .1v increments up to 7v, then jumps to 7.5v. I don't know why castle did it that way.
I talked to a castle tech about wiring the pro with 1 of the wires to the servo and 1 to the rx since it has two leads, he stated that there would be a concern with the bec seeing different grounds and possible feedback or failure. It is best to have both plugged into the rx, you can use a y harness if you don't have a 2nd plug available.
He also stated that the pins in a standard servo plug are only rated for about 5A, which is why they put two power wires on the pro.

as others have said, the spektrum rx's are rated up to 9.6V and hitec claims you can run the servo off of a 2s LiPo which will put out 8.4V fully charged. I see no issue with running it at 7.5V if you feel you need the extra power over running it at 7V

 

[Irishchamp]

interesting how continuous amps goes down as input voltage goes up. it only starts the diagram at 16 volts input but it looks like the closer you are on input and output voltage on the BEC Pro the better performance your going to get. I guess I will also wire up my 6s a123 pack somewhat separately so I can run the BEC off of 9.9 volts instead of the final 19.8 volts.

upss...sorry my bad
cc bec pro has limited info but i just saw this
http://www.castlecreations.com/media/press-releases/pr-ccbecpro.pdf
they said that '1/10th increments' for ccbec pro too CMIIW

 

[Lushtrucker]

so the issue is having one of the BEC Pro plugs going to the RX and the other split between the RX and Servo? what if both plugs on the BEC Pro were going to two servos, that way no discrepancy in ground signal? if the RX can receive and supply 5 amps per pin connector is that peak or continuous? if thats peak then I would basically be downgrading my BEC Pro to a standard CC BEC with a 10 amp peak rating. if its continuous then maybe it would allow the whole 20 peak amps through from the BEC Pro. The RX can then just receive power from the BR-XL's on board BEC instead of disconnecting the red wire.

I do believe the 5A rating on the servo plug was a continuous rating.

If you pull an rx out of the case you will notice that the + and - pins are all tied together on a bar. I have heard that this allows for a good bit of current to flow with no ill effects on the rx components. I don't know exact draws and such, but I can tell you I have my bec pro feeding into my ar6100 rx and have no issues at all with any shut downs. in a few months I will be trying this set up on a super and will find out if it will feed 2 large servos reliably.

side note: I went with the pro because I could not get away from rx shut downs during a comp using the regular bec on my berg when I was running dig switches and a 7955, I tried wiring it every way imaginable with no fix. I believe the sidewinder's bec is even weaker than the mm bec, which may be why the dig switches would over-load it even with the epa's set properly.

 

[Lushtrucker]

interesting how continuous amps goes down as input voltage goes up. it only starts the diagram at 16 volts input but it looks like the closer you are on input and output voltage on the BEC Pro the better performance your going to get. I guess I will also wire up my 6s a123 pack somewhat separately so I can run the BEC off of 9.9 volts instead of the final 19.8 volts.

it is purely a relationship between amps and heat. the more you step the voltage down, the more current is used in the process, more current = more heat.

are you planning to make 2 3s packs? I would caution you away from tapping into the middle of the pack to get a lower voltage for the servos and such, it could lead to cell damage from an over-drained cell.

if you are running a 6s a123 pack, why don't you just pick up a tiny 2s lipo pack to run the rx and servos? I think the pro bec will work fine, but you are asking it to drop the voltage quite a bit.