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Resilient
12-26-2008, 11:17 PM
What do you use to power your SCC-32 servo controller? Can I power it all off of one battery? They seem to suggest its possible, but it looks like you need one > 6v for the logic and one < 6v for the servos.

Thanks
Justin

Adrenalynn
12-26-2008, 11:23 PM
The SSC32 needs at least 5.5v to run - a 6v battery won't deliver more than 5.5 for long, esp. not when powering servos too.

I use a 7.2v battery and a CastleBEC for the servos. The BEC will step the voltage down to 6v for the servos and the 7.2 (9v max to the SSC32) powers the SSC32 directly.

Resilient
12-27-2008, 12:51 AM
Is there a low voltage cutoff on the CC BEC? I would like to use my LiPo batteries but always worry about discharging them too far if I accidentally leave it plugged in or something.

Adrenalynn
12-27-2008, 12:59 AM
Nope - there are other *switching* BECs specifically for LIPO. Check out Hobbywing, for example.

Resilient
12-27-2008, 01:18 AM
I notice you have switching is bold letters with some stars... Is this more significant for a application like this than an RC application? As far as I have been concerned, switching vs. linear BECs are really the same except that its a bit harder to melt a switching BEC :P

Adrenalynn
12-27-2008, 01:52 AM
Drop-out voltage, for one, for another really biggie - current handling. Much harder to find a 10A or bigger non-switcher. Efficiency, for another. Heat? That's a pretty biggie. Stability of power. Noise around the servo wires.

Yeah, the list does go on a bit. :)

DresnerRobotics
12-27-2008, 09:56 AM
I always power servo and logic separately on the SSC-32. On my projects which are usually 14-20 servos, they'll pull too much at once and cause the logic to dip, resetting the SSC-32. Easier just to separate the two.

4mem8
12-27-2008, 12:32 PM
Definitely go split P/S for the SC32, As Tyberius has stated those servos can draw a lot of current as I am finding out.

Adrenalynn
12-27-2008, 12:58 PM
Right - that's what the BEC is for (you use the same one, 4Mem, right?)

4mem8
12-27-2008, 07:09 PM
Correct, Adrenalynn, I have two of them that I will be using om my J5.

Resilient
12-29-2008, 10:22 PM
So how much current will my servos draw? I know it depends on the servo, but lets say a HS-55 on the small end of things and something like a HSR-5995TG on the big end?

I can find that the HS-55 pulls 150mA operating at no load, but thats not super helpful and I cant find anything on the 5995.

Thanks for the help so far!

Adrenalynn
12-29-2008, 11:12 PM
That's the big mystery - crummy documentation. The only good answer I've been able to come up with is "measure it and find out". About 850ma for an HS-675MG at moderate load. Almost 2A for an 805BB near stall. (Both @ 6v)

Quantum
12-30-2008, 01:32 AM
The 5995 are older versions of the current 5990.

They have the same rating but are not heatsinked. Otherwise same servo.
I would not even dare trying to push this servo that much as it will melt and I can
show a couple of pics of that.

The 5995 are rated 6.0V no load 300mA & 7.4V 340mA no load
stall current 6.0V is 4.2A & 7.4V is 5.2A

Just dont strain them to much

Paul

Adrenalynn
12-30-2008, 01:34 AM
"push them" how much?

They will draw whatever they want to draw current-wise, the only control you have is the voltage you put in.

Quantum
12-30-2008, 01:44 AM
You also have control over the application. Basically the more you lift the load increases to the point where pop no more servo. I am I wrong on this I have never checked this out (experiment time). I assumed the more you lift weight wise the load increase not exactly linearly but to point where you push the servo to its max.

Adrenalynn
12-30-2008, 02:08 AM
Sure, the closer you get to stall the more current will be required. Amps = Power = Work.

If you have any servo that can't handle the power requirements of something close to its rated load, I suggest filing it in the round bin and never buying from that manufacturer again.