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

[Irishchamp]

I just purchased a castle link so I could run my servos at 7.4 volts however when I hooked up the castle link there was no setting for 7.4 volts, only 7 or 7.5? anyone know how do get around this? should I just run my servos at 7 or 7.5 volts?
thanks

[Irishchamp]

I also wanted to ask for some experienced insight on wiring up the servos to the bec, as of now I'm doing it like Castle Creations says, I have the two plus going to the 6th and 7th channels or my DX6 receiver. is there any disadvantage to doing it this way, should I be wiring the servos direct to the BEC?
thanks again in advance.

[deephis46]

I wired just like this...

[Irishchamp]

Thanks for the diagram! However, what's the advantage to doing it like this? Does it get better power this way?

Originally Posted by deephis46

I wired just like this...

[Sharkey]

the receiver may not like 7.4 volts, they are designed to run on 6 volts. then again, with nitro stuff a fully charged 5 cell hump pack is around 7 volts fully charged and nobody has problems with that. another thing to keep in mind is that servo will pull more than 4 amps at stall, the receiver may not be able to handle that sort of current.

id directly wire the servo.

[hitman46mod]

Originally Posted by Sharkey

the receiver may not like 7.4 volts, they are designed to run on 6 volts. then again, with nitro stuff a fully charged 5 cell hump pack is around 7 volts fully charged and nobody has problems with that. another thing to keep in mind is that servo will pull more than 4 amps at stall, the receiver may not be able to handle that sort of current.

id directly wire the servo.

I don't see any power going to the RX from the BEC in that diagram. Just from the ESC. And with the castle link you should be able to change the voltage from 4.8v to 9v in .1v increments. I dont see the problem here. And as far as I have read some people are running as much as 8v through the RX. So if you want to run your servos off the BEC that is how its done.

[cato]

Originally Posted by Irishchamp

Thanks for the diagram! However, what's the advantage to doing it like this? Does it get better power this way?

IMO this is best way to hook it up. Gives two power sources. ESC controling the rx and persay dig; BEC powering only the St. servo. Signal wire only going to RX. Less chance of shutting system down since servo is isolated. If you can't adjust BEC to 7.4 then just run it at 7....Hope that helps!!

[indiana mudcat]

There's no issue with 7.5, I would see no problem with running a 7.4 rated servo at 8.4 myself. You can plug 2s lipo straight into it and thats 8.4.

[Irishchamp]

Yea, I don't think 4 amps is enough for two 7950's. That's what I needed to know, I was not sure if receivers let enough amps through. Thanks

Originally Posted by Sharkey

the receiver may not like 7.4 volts, they are designed to run on 6 volts. then again, with nitro stuff a fully charged 5 cell hump pack is around 7 volts fully charged and nobody has problems with that. another thing to keep in mind is that servo will pull more than 4 amps at stall, the receiver may not be able to handle that sort of current.

id directly wire the servo.

[Irishchamp]

I don't know what I'm missing then. Maybe I'll try the software on the disc not from their site. Is becpro different than standard?

Originally Posted by hitman46mod

I don't see any power going to the RX from the BEC in that diagram. Just from the ESC. And with the castle link you should be able to change the voltage from 4.8v to 9v in .1v increments. I dont see the problem here. And as far as I have read some people are running as much as 8v through the RX. So if you want to run your servos off the BEC that is how its done.

[Irishchamp]

Yea I thought about the 2s lipo thing but I'm not sure at what amp load lipos voltage drops off and to what.

Originally Posted by indiana mudcat

There's no issue with 7.5, I would see no problem with running a 7.4 rated servo at 8.4 myself. You can plug 2s lipo straight into it and thats 8.4.

[Szczerba]

Originally Posted by indiana mudcat

There's no issue with 7.5, I would see no problem with running a 7.4 rated servo at 8.4 myself. You can plug 2s lipo straight into it and thats 8.4.

I would not run that servo at 8.4v unless you want to buy another one soon. I'm pretty sure the max input voltage is 7.4v and anything after that is just heat.

http://www.servocity.com/html/hs-7950tg_servo.html

Look at the detailed description.

Honestly, I think they misrepresented that 2 cell lipo description. I run mine at 7.0v.

[indiana mudcat]

All the new 7.4 volt stuff is made to plug 2s lipo straight in so nitro cars don't have to run a BEC.

[Sharkey]

thats exactly it. as i said earlier, most current servos are designed for 4.8/6 volts, however a fully charged 5 cell receiver pack is over 7 volts fully charged. im sure the next gen hv servos will take a 2s lipo fully charged without issues. my only concern is the receivers.

[indiana mudcat]

KO PROPO rx (at least the new ones) are rated for 2s.

[Phyuck Yiu]

Originally Posted by Sharkey

thats exactly it. as i said earlier, most current servos are designed for 4.8/6 volts, however a fully charged 5 cell receiver pack is over 7 volts fully charged. im sure the next gen hv servos will take a 2s lipo fully charged without issues. my only concern is the receivers.

Spektrum receivers are rated for 9.6v. I run 3 8711hv's through my receiver with a 2s lipo feeding both sides of the bus. I also run a standard 8711 on 2s lipo through the receiver.

[Irishchamp]

So it sounds like I could run my two servos through the receiver or not. I'm going to be running 6s a123 so I definately need to limit voltage to the receiver. Maybe I'll use the onboard BEC in one of the holmes br-xl's for the receiver and run the servos direct off the BECPro.

Originally Posted by Phyuck Yiu

Spektrum receivers are rated for 9.6v. I run 3 8711hv's through my receiver with a 2s lipo feeding both sides of the bus. I also run a standard 8711 on 2s lipo through the receiver.

[Phyuck Yiu]

Originally Posted by Irishchamp

So it sounds like I could run my two servos through the receiver or not. I'm going to be running 6s a123 so I definately need to limit voltage to the receiver. Maybe I'll use the onboard BEC in one of the holmes br-xl's for the receiver and run the servos direct off the BECPro.

The receiver will take the load, I just don't know if the bec will supply enough voltage under load to prevent rebooting. Using one of your esc's bec's would eliminate any chance of a reboot, but if you are willing to test using the cc bec running everything it won't hurt anything.

[Irishchamp]

Cool, good info! Thanks.

Originally Posted by Phyuck Yiu

The receiver will take the load, I just don't know if the bec will supply enough voltage under load to prevent rebooting. Using one of your esc's bec's would eliminate any chance of a reboot, but if you are willing to test using the cc bec running everything it won't hurt anything.

[deephis46]

Originally Posted by Irishchamp

Thanks for the diagram! However, what's the advantage to doing it like this? Does it get better power this way?

I use that way because i often set my sidewinder and ccbec to castlelink to find my best setting. no need removing red cable from esc because it needs when it connected to castlelink.
Also with that diagram you can use a 2nd battery to supply power to the servo stand alone without bothering main battery, but watch the voltage though
oh, and my castlelink (downloaded from cc site) works fine, there is an 7.4v option. you might check your castlelink software