Servo Voltage

[Roger Dyke]

Hi All,

I have just ordered two Futaba S3115 Mini servos. After ordering, I've noticed that the Futaba specification states 4.8 volt only, and warns of damage if this voltage is exceeded. My system runs on 5.0 volts from the ESC (via the receiver). Have any of you out there ever had any problems with these servos using 5.0 volts?

Futaba do not seem to indicate any form of voltage tolerance.

Roger

[John Privett]

Roger - 5.0v shouldn't be a problem.

An 'old-style' 4.8v NiMH or NiCd starts at well over 5v when freshly charged - I often get readings on my telemetry of 5.2v in the first few minutes from models equipped with them.

They just mean don't use a 5-cell (6v) NiMH or higher.

[Roger Dyke]

Sorry John, I told a little porky. I have just checked the specification of the BEC from the ESC and it is specified as 5.5 volts at 5 amps. Do you think this is too much for the servos?

[John Privett]

Good question Roger! That's a bit higher than a 4.8v battery, but not as high as a 5-cell, 6v one.

Looking at the FutabaUSA datasheet they say;

"Using the supply voltage higher than 4.8V or applying high load to the servo will shorten the life."

My take on that is that you may get a shorter life from the servo, but as long as it's not heavily loaded maybe not a problem. I suspect there are people using these servos on 5-cell batteries without even realising that it's advised against.

Let's see what others reckon!

[Roger Dyke]

I have just rang Futaba Customer Service, and the guy there assures me that the Futaba Mini Servo S3115 is good for up 6 volts like the S148 and that the stated voltage is nominal (in line with the 4.8v NiCd battery pack). He says that they are aware that more flyers now are using electric flight with the BEC supplying 5.0 or 5.5 volts and that is fine.

So that is job done I think (I hope)

John: Thanks for your input.

Roger