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Servos and LiFe batteries

Old 10-15-2016, 10:43 AM
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Jack_K
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Default Servos and LiFe batteries

Will most servos be OK with the 6.6 volt LiFe receiver batteries? I think the batteries actually charge up to 7.4 volts.

Jack
Old 10-15-2016, 12:26 PM
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Gizmo-RCU
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Jack,

I use LIFE and have never had any problems. Most Servo's today give values for both 4.8 and 6 volt performance . Guess if you are using really old servos there could be a problem? I know several
local guys that are really anal and would not use LIFE on some Servos that were old enough that only 4.8 specs. were available. Did some research and found that the higher values were fine and current
information was available by inquiry to the vendor (Futaba in one case). I recently gave a friend a Smoke Pump nib and he installed it and boy did it put out, and then failed. Read the small print and it was for 4.8 volt,
The pump had been in my shop for years............
Old 10-15-2016, 12:55 PM
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Jack_K
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Originally Posted by Gizmo-RCU View Post
Jack,

I use LIFE and have never had any problems. Most Servo's today give values for both 4.8 and 6 volt performance . Guess if you are using really old servos there could be a problem? I know several
local guys that are really anal and would not use LIFE on some Servos that were old enough that only 4.8 specs. were available. Did some research and found that the higher values were fine and current
information was available by inquiry to the vendor (Futaba in one case). I recently gave a friend a Smoke Pump nib and he installed it and boy did it put out, and then failed. Read the small print and it was for 4.8 volt,
The pump had been in my shop for years............
Thanks. I was worried about some old Futaba servos I have, S128, S138, and S148. They all have 6 volt ratings, but I'm just uncertain about the fully charged voltage of the LiFe.
Old 10-15-2016, 03:46 PM
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Zeeb
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Originally Posted by Jack_K View Post
Thanks. I was worried about some old Futaba servos I have, S128, S138, and S148. They all have 6 volt ratings, but I'm just uncertain about the fully charged voltage of the LiFe.
Not sure about those older Futaba's but if they are rated for six volts that means they can take a five cell NiCD/NiMH. Those come off the charger at 7.2 volts.

Now there are some heli servos/gyros that when they say "6 volts", they mean exactly 6 volts.
Old 10-15-2016, 04:06 PM
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aghost
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I run LiFe batteries for the RX in a six planes (at the moment). There are about 20 Futaba S3003 and S3004 servos among these planes. The 3003 is a replacement for S148 and S138 and others. The 3003 servo spec sheet shows torque values at 4.8 and 6.0V. Never had any problem with this battery/servo combination over 5+ years. But I can't answer your question about the even older Futaba servos.

Brian
Old 10-15-2016, 04:22 PM
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Yes a life battey is 7.2 volts of the charger. But within a few minutes it's down to 6.6/6.7 volts, and sits around there for a while.

I started using them this year, and no problems. I havs a few s3003, as well as hitec and jr. If they are ok for 6 volt nimh or nicd, the a life should be fine.
Old 10-15-2016, 05:41 PM
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All Day Dan
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Jack, get the answer from the one who really knows, the manufacturer of your servos. You have no idea what the qualifications are, or lack of them, from the guys on RCU. And don't forget to ask them about the receiver and anything else you have plugged into it. Dan.
Old 10-15-2016, 06:07 PM
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I have some older Fut S148 servos in use and about 8 years when I switched from 4 cell 4.8v NiCad to using a 5 cell 6.0v NiCad in my 2.4 systems I posed the question to Bax the Fut rep who advised me that the servos would be okay on 6.0v. Then about 3 years I switched again to using Life 2 cell packs exclusively to power the same servos and so far no problems.
Old 10-15-2016, 06:29 PM
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Gizmo-RCU
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Dan,
He asked advice here and I gave him solid advice. I had went to Futaba and pointed that out. The other guys also gave solid advice from their extensive use of various servos. I also advised the OP
look up the ratings on the various servos, in your view that can't be trusted?

To me that is as good as talking to someone on the phone, etc..

Mostly I really didn't like what you infer about RCU folks!
Old 10-15-2016, 06:44 PM
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Some of the very best information and advice I ever got related to this hobby came from people right here on this RCU forum.
Old 10-15-2016, 07:32 PM
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Truckracer
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Originally Posted by Jack_K View Post
Will most servos be OK with the 6.6 volt LiFe receiver batteries? I think the batteries actually charge up to 7.4 volts.

Jack
As others have stated, 7.2V is full charge for LiFe batteries and that voltage goes down to under 7V soon after removing the batteries from the charger. Normal working voltage is 6.6V and the batteries stay very close to that value until depleted.

Futaba readily supplies info on working voltages for most of their equipment unless it is really old.
Old 10-16-2016, 05:41 AM
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Nearly all Servo manufactures provide the necessary information, just Google them and there it is!
Old 10-16-2016, 07:41 AM
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Jack_K
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Originally Posted by Gizmo-RCU View Post
Nearly all Servo manufactures provide the necessary information, just Google them and there it is!
I have Googled the S128, S138, and S148. All give specs for 4.8 and 6 volts, but not for 6.6 and higher. Some of my other brands allow up to 8 and even 9 volts.
Old 10-16-2016, 08:40 AM
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Truckracer
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Futaba has OK'd the 148 for use on 6.6V in a conversation I had with them several years ago. This has been confirmed online by Futaba / Great Planes reps on several occasions. As you said though, not the 128 and 138 but these last two servos are getting pretty old these days. Should probably be retired anyway for any critical applications. I wonder about some of the very early 148 also as this servo has been made for a very long time with several different board / internal revisions. Perhaps not all versions of the 148 are suitable for 6.6V. I simply don't know.
Old 10-16-2016, 01:13 PM
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I used up all my 128-38 and 48 servos as throttle servos and then that was a long time ago. I was using 6 volt Nicads and NiMH............never had a problem damaging the servos. It said 6 volts and I went for it knowing the fully charged pack was higher than 6 volt.
Old 10-16-2016, 04:05 PM
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Gizmo, good input. We invest a lot of money and time in to our model airplanes. They are hazardous objects to life and property. The only person qualified to discuss the ratings of our radio control equipment is the person who designed it or their representative. Unless that person is on RCU, like Bax for Futaba , anyone else can only describe their experiences which is not sufficient considering the damage an out of control model can cause. Here is a one case I know about. One of my flying buddies put a lithium based battery pack in to his JR transmitter that was designed for NiCads. It took a few minutes for the regulator in the transmitter to get fried because of the increase in voltage applied. He was flying a 1/3 Cub with all high end JR equipment in it. Luckily the plane was totaled away from the pits. I respect the OP for posting such an important subject and all the guys taking time to explain their experiences. But experiences are not valid design information. By the way, have you noticed that all the manufactures have come out with a line of high voltage servos and receivers? Dan.
Old 10-16-2016, 05:45 PM
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Dan,
In the one case I received direct in-put from BAX(Futaba) here on RCU. I am very aware of the HV rating on many newer servos, all that is so easy to look up and more than a few of mine have that (Savox). In the case of your buddy, what was he thinking, doubt anyone would have told him to do that? I would never take someones word on such unless they had done so themselves, kind'a like here.
If I pass on information I will qualify if not sure or suggest going to the mfg. Some things are beyond the average RC'rs ability (mine for sure) and should be addressed only by a qualified person.
Having been a safety officer with the largest club in the area I am very tuned in to that aspect of the sport also.
Been building and flying for many years........learned that if you tempt faith you will get bit!
In this case What I and others posted has come from years of positive experience on the subject. The good thing is you are not bound by that and can do your own thing, what the heck you don't know me.
Old 10-16-2016, 06:20 PM
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Originally Posted by All Day Dan View Post
Jack, get the answer from the one who really knows, the manufacturer of your servos. You have no idea what the qualifications are, or lack of them, from the guys on RCU. And don't forget to ask them about the receiver and anything else you have plugged into it. Dan.
Somebody p*ss in your Wheaties today?

Get off it man, all you are doing is irritating folks who are trying to help. You'll notice the sticky about "what would I do if I ran RCU?" It's because folks like you spend WAY too much time on these forums with no real useful input. My suggestion for improving RCU would be to ban guys like you.....
Old 10-17-2016, 07:13 AM
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Jack_K
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You guys sure have messed up the thread I started. Let's be gentleman. It's just a sport!
Old 10-17-2016, 08:19 AM
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Gizmo-RCU
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Don't think I did anything wrong except defend myself and try and give you your requested information! Sorry
Old 10-17-2016, 09:04 AM
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BAX and the lady from Great Planes (Futaba), sorry I forget her name, have posted often on the various forums regarding this subject. Google searches should show this info and confirm or disprove any info provided by those posting in the forums. Overall, in this thread I believe the OP has received reasonable and proper info to move forward with.

I'm a very conservative RCer but there are limits. When I read questionable info I confirm it one way or another by seeking other sources for confirmation. Yes these sources include the mfgr. when available.

Like many dangerous activities in life, if we allowed all our concerns and fears to control our actions, no RC airplane would ever leave the ground! Most of us follow a reasonable path and avail ourselves of as much info as possible to make our hobby a safe one. At least as safe as it can be.

Away from RC, when I was racing I accepted certain risks realizing that I could be seriously injured or killed and that my normal health insurance probably wouldn't cover my bills. I further realized I could possibly injure or kill someone and that I could be sued for my actions. I accepted that risk also. If I hadn't accepted those risks, I could not have participated.

The same story pretty much applies to full scale flying. When flying, once again I accepted some of the risks and insured those risks where the premiums were within reason. Many things were not insurable so I accepted the risk. Had I not accepted some risk, I couldn't have left the ground.

In our lives, we make educated, calculated risk decisions all the time. RC flying is no different and is just an extension of our normal lives.

Last edited by Truckracer; 10-17-2016 at 09:08 AM.
Old 10-17-2016, 01:53 PM
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[QUOTE=Truckracer;12268222]BAX and the lady from Great Planes (Futaba), sorry I forget her name, have posted often on the various forums regarding this subject.

Her name is Krysta.
Old 10-17-2016, 05:13 PM
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Truckracer
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[QUOTE=karolh;12268310]
Originally Posted by Truckracer View Post
BAX and the lady from Great Planes (Futaba), sorry I forget her name, have posted often on the various forums regarding this subject.

Her name is Krysta.
Thanks, senior moment left me with a void where her name once was!
Old 10-17-2016, 07:08 PM
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[QUOTE=Truckracer;12268357]
Originally Posted by karolh View Post

Thanks, senior moment left me with a void where her name once was!
Happens to the best of us, and nowadays it happens much more often to me
Old 10-22-2016, 03:26 AM
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Originally Posted by Jack_K View Post
Will most servos be OK with the 6.6 volt LiFe receiver batteries? I think the batteries actually charge up to 7.4 volts.

Jack
Most yes, modern servos that carry a 6v rating are rated for a 5 cell nickel pack and they are fine with Life/A123

As noted there are a few exceptions but they are increasingly rare.

Krysta is awesome, we share a birthday


As for the rest of it, y'all settle down, its a hobby, have fun and go do some flying

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