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HelicopterRadio - Futaba FASST › Futaba S9303 Servo using 2S LiFe 6.6v battery
08-29-2017 05:04 AM  28 days agoPost 1
JLF92677

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Southern California

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Has anyone successfully applied Futaba S9303 Servo using 2S LiFe 6.6v battery without damaging the servo?

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08-29-2017 02:56 PM  27 days agoPost 2
HilliHeli

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S.MI./FL.

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Sent ya' PM with some info

!Antriebe, die bewegen!
Jazz', Jives & vbar's
Futaba FASST / FASSTest

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08-29-2017 10:26 PM  27 days agoPost 3
JuanRodriguez

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The Villages, Florida

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Why not post the "info" here so that others can benefit???

Been there, done that and old enough to know better.....

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08-29-2017 10:42 PM  27 days agoPost 4
HilliHeli

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S.MI./FL.

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I simply asked him to be careful of the temp. of the servo(s) when running at a higher voltage than what is recommended by the manufacturer.

!Antriebe, die bewegen!
Jazz', Jives & vbar's
Futaba FASST / FASSTest

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08-30-2017 12:03 AM  27 days agoPost 5
JuanRodriguez

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The Villages, Florida

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A friend of mine and I have been running 2S LiFe batteries with all standard servos with the exception of a step down reg for the Fut 9253/54 and have had no issues..... this was all before the "HV" revolution......

If one were to do a search on the topic in general, there are many, many others doing the same thing without running a separate regulator for the "standard" servos......

My take on it is that back in those days before the HV stuff started to become popular, everyone was running the 4 cell 4.8 V NiCd or NiMh packs and as such, the manufacturers used that voltage as a "base line" to rate the speed and torque of their product.....

Then, some folks started using the 5 cell packs, no problems...... if you do the math, the voltage of a 5 cell pack is very close to the voltage of a 2S LiFe battery......

So with that rationale in mind, many concluded that using the 2S LiFe without a regulator was fine.....and it has proven to be so in my experience.......

Been there, done that and old enough to know better.....

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08-30-2017 05:26 AM  27 days agoPost 6
JLF92677

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Southern California

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Juan, below is the info provided by "HelliHelli":
HilliHeli wrote on 08-29-2017 06:55 AM:
Hey JLF92677,
I can only find a few postings on this topic for the Futaba S9303 servo.
Seems there were a few that wanted to have the same questions answered.
I see that someone posted that there should be an increase in torque of about 25% when running the S9303 at 6.0V (125 oz. at this voltage).
Remember that a fully charged 2S LiFEPO4 (LiFE) pack will be at 7.2V.

I have run the newer Futaba servos that were rated for 4.8V at higher voltages without problems and I know of a few that have even run Futaba servos that were rated (on the low-end) at 4.8V on voltages up to 8.2V (2S LiPO).
I would be careful with your S9303's and running anything over 6.0V.
These are an older (now discontinued model) and because of their age the voltage may cause damage.
When I do run servo (JR or Futaba) at a voltage that is higher than what was originally recommended I will always remember to let things cool-down between Flights.
I would also suggest that if you were to run your S9303's at 6.6V that you should try to monitor the temp of the servos with a temp gun (if possible).
If you do not a temp gun I would simply do as I have in the past and carefully touch the servos to see if there is extreme heat.
If they are getting very hot I would suggest not to run them at these higher voltages.

Hope that Helps

!Antriebe, die bewegen!
Jazz', Jives & vbar's
Futaba FASST / FASSTest
Juan, I tend to agree with you, as servo driver PCB components and motor technology for those servos only rated 4.8V at the time are most likely the same as servos of the same time frame that were also rated for 6V.

It would be good if Futaba can weigh in on this, but so far I have not been able to get any response other than 4.8V with no further explanation.

Dr. Ben, any input from you on this?

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08-31-2017 04:50 AM  26 days agoPost 7
Dr.Ben

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Richmond, VA, USA

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Though the published ratings were always based on 4.8v nominal voltage, you'll probably be ok on Life voltage once it has settled to its nominal 6.6v. A lot of the original analog servo testing was done on voltage equivalent to 4 dry cells or an even 6v, pretty close to plateau Life voltage.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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