View Full Version : HITEC Servos: Can the OEM RN-1 Servos handle 7.4V?

06-19-2008, 02:25 PM
I am sure someone has asked and been answered here but I can't find an reference to the question:

Can the servos that come with the RN-1 set be run at 7.4 Volts?
Can you change the geartrain out for a metal one to enable higher torque, power and speed?

I'm transforming my RN-1 into a little Armored Core and I see the weight issue rearing its ugly head. While the world is used to americans being overwieght, I'd like my bot to be a powerful as it looks... I've worked out some suspension linkages that should remove a lot of what gravity will do to the beasty but I'd like to know if I can beef up some of the servos I've already invested in.

So far the SuperNova has 34 DOF (I'm running both boards). I'll Post some piccies of my progress on the model tomorrow.

You are all very informative/knowledgable but above all I value you for the inspiration you continue to provide.


06-19-2008, 03:28 PM
Technically 6v rated servos can be run at 7.2v... usually the higher end ones tend to do this better, I've heard of some of the lower end ones getting the twitters and acting weird.

I'd say with these type its certainly possible- you are already aware that you're runnign them out of spec so I'm sure you're aware of the risk. What I'd recommend is designating one servo as a guinea pig, running it at 7.4v for increasingly long periods of time (start with 30 seconds, 1 minute, 3 minutes, 5 minutes, etc) and closely monitor the temperature of the unit. If you can get it running at 15-20 minute run times without burning up I'd say you're probably golden.

Edit: Make sure to put some load on it while testing though.

06-19-2008, 03:40 PM
The reason I ask is that the newer models are able to run at the higher voltages.

I have to look closer. Perhaps my motors are not the coreless type that the new serrvos boast. The geartrains can't be the only reason for the higher specs.

06-20-2008, 02:35 PM
Hi MYKL since your running so many servos, and burning them up doesn't sound like a good idea, why don't you try to find a voltage regulator with a high enough amp. rating to keep from cooking them? Plus you could then run other applications eg: gyros, accelerometers, bluetooth, video or whatever you want. thnx john

06-21-2008, 02:00 PM

My experience with those servos is that the faster speed you run them at the hotter they get and I would guess that if you are running both higher amps and higher speed actions you are really very likely to blow the servo.


06-21-2008, 03:16 PM
I tend to agree, and would not risk running at that voltage, I have used many types of servos in my model aircraft and found that 6v is best, But as tyberius has stated the later 6v versions may be able to run at 7.2v but be cautious.

06-21-2008, 04:07 PM
Technically, higher volts = lower amps. More speed, less power.

That said - there's a good reason for the limits. I wouldn't push them very far without manufacturer's approval.

06-23-2008, 08:48 AM
Thank you all. I shall run them as specified.

If I need more poop I'll buy the newer models and place them where needed.

I'm sure the torque will be needed in the legs. I'm running two boards so I can power the one that commands the legs at the higher voltage with the bigger servos If the bot seems under powered.


06-23-2008, 01:59 PM
Keep an eye on the current-draw from your power supply. If you're short of torque the current drain (amps) will go up, regardless of volts. Maximum current draw happens at stall, but you can ramp up there pretty quick if it starts hitting any real load.

06-23-2008, 02:59 PM
So you have every servo attached to a meter whilst you program your bots?

I need to look at my GUI closer but, I don't think it includes a amprage reading. Its should with the capabilaties of these servos. I'll look closer.

Thank you for your help.

I need to get an AC/DC power supply so I can have more time on the programming table...


06-23-2008, 04:39 PM
I have a ammeter inbetween my power supply and my controller. If I start sucking more than my regulator can deliver reliably, I shut-down and diagnose - ie. I pull servos and test each under load to build a profile.