Can this ESC handle 4 servos? - RC Groups
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Dec 11, 2003, 03:53 PM
Registered User

Can this ESC handle 4 servos?

I posted this question in the GWS forum but I did not get any replies, so I am trying it here.
I built my GWS Corsair using an ICS-400 ESC. I am using 3 servos now for aileron, elevator and retracts. I want to add rudder control also but I do not know if the ICS-400 can handle 4 servos.

Is it safe to add a 4th servo or will it damage the ESC?

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Dec 11, 2003, 03:57 PM
Under tension
citabria's Avatar
The ICS 400 will have no problem at all with four servos. It's a solid 15A controller. I've used them on more than one plane with 4 servos.

Dec 11, 2003, 04:08 PM
Registered User
You don't mention what brand and model servos you're using. I found out the hard way that the 4 BMS Bluebird servos in my speed 400 sailplane were too much for the BEC in my 25A Castle SC to handle (shutdown city). Switched to 4 HS 55's and problem ended.
Be careful, 4 is pushing the limit,

Dec 11, 2003, 04:12 PM
Registered User
I am using the 9 gram servos sold by ALLERC.COM. They are the same size as the HS-55 servo.
Dec 11, 2003, 04:13 PM
Registered User
What servos and what battery?

The BEC on that controller is rated for 1.2 amps at 8 cells. The more cells you have the more heat (power) the BEC has to dissipate.

I've read of at least one EZone reader who smoked the BEC by trying to run four servos with a 3s (11.1v nominal) Lipo battery.
Dec 11, 2003, 04:19 PM
My hangar is,... "almost" full
No Step's Avatar
I looked around on some web sites and couldn't find anything that says how many servos it will handle either. But >>as I understand it << , it won't damage the ESC , it will just not be able to handle current draw of all the servos and fail to operate servos & reciever resulting in a crash. I know, big help ?! I am no expert. Alot depends also on how smoothly (no binding) the surfaces move thus resulting in minimal current draw to begin with. With the single servo/linkage setup on the GWS Corsair, there might be a good amount of current draw there on that servo. Wish I could help some more. Maybe someone with more experience with this ESC will chime in.

Fred G.
Last edited by blaze; Dec 11, 2003 at 04:21 PM.
Dec 11, 2003, 04:23 PM
Registered User
The specs on those servos are Speed (sec/60) .11, Torque 1.1/15.3 (4.8 V)

The specs on HS-55s are Speed (sec/60) .17, Torque 1.1/15 (4.8 V)

So you could infer that the servos you are using must be using more amps because they provide the same torque but are significantly faster (.11 vs .17) The difference in speed must be because the motor is hotter or the gearing is different.

But actual current useage can only be found by testing due to efficiencies, etc.

I always try to test out my controllers BEC capacity first by hooking all the servos up and wiggling the stick around as if I'm flying. (not very accurate since there's no load on the servos but it is fun to do) If the ESC gets so hot you can't touch it, you're asking for trouble.
Dec 11, 2003, 04:50 PM
Registered User
All my battery packs are either 7.2v NICD or 8.4v Li-ion and Li-poly. I wouldn't want to damage the esc so I figure I will just stay with the setup I have now or remove the retracts and add the rudder.
Dec 11, 2003, 04:56 PM
Does anyone hear a cat?
headless's Avatar
Curious; could one use a clamp meter around those smallllllll wires on a servo -- maybe just the hot wire, and actually measure the current it's pulling? Are clamp meters not accurate enough for wire that small?
Dec 11, 2003, 06:17 PM
Nickel what?
Phreakish's Avatar
I was thinking about this earlier, and isn't the BEC really just a voltage regulator? Whats to stop someone from bypassing the BEC in the normal rx and using something like an +5v regulator? I have a couple that run at 3A at 12V...
Dec 14, 2003, 03:46 AM
Registered User
The BEC is in the ESC, not the Rx.

No problem running a separate BEC, just disconnect the red (+) wire from the ESC - Rx connector so that the ESC BEC is not supplying power to the Rx.

Just make sure the voltage regulator puts out a voltage that your servos and Rx expect. Connect the input to the drive battery and the output to the Rx red and black (+ -) connectors on an unsued channel.