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A123 battery too much for 4.8 V rated servos. - 4/12/2012 9:24 PM   
jetwash


 

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From: Henderson, NV, USA
Status: offline 		Hi guys, Iam switching to A123 batteries on all my jets. The freshly charged A123 batteries burned 4 servos, JR3321 in one of my jet. Fortunatelly that happened on the ground. I guessed those wing servos are rated at 4.8V only. Any one having burned servos using A123 batteries. Iam using Futaba 6014 14 channels receiver. The jet didnt have any issues with JR Nimh 5 cells prior to switching.

Ken

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RE: A123 battery too much for 4.8 V rated servos. - 4/12/2012 9:32 PM   
jroth



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Status: offline 		Hi,

There have been many reports, including my own, that there have not been issues using 20 year old servos with JR/Spektrum receivers and A123 batteries. I know that I have used Futaba S-148 servos and JR NES-517 servos on air valves without any problems.

I wonder why your servos burned up?

Who can tell us?

thanks,

John


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RE: A123 battery too much for 4.8 V rated servos. - 4/12/2012 9:36 PM   
lfinney


 

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Status: offline 		my exp with a123 has been with 3000 series futaba, 9000 series futaba, and ds821 servos as well as 3 series hitec series. three years and counting zero problems

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RE: A123 battery too much for 4.8 V rated servos. - 4/12/2012 10:24 PM   
sidgates



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Status: online 		A lot of the older servo components were never designed for voltages above 5.6volts. I am surprised how many guys get away with 6.0volts and sometimes more. On all my 4.8volt servos I never run more than a 4 cell nicad pack.

Why take a chance when there are now high voltage servos available for up to 2 cell lipo packs.

I speak from a little experience having been involved in the production of several thousand servos over the past 42 years.

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RE: A123 battery too much for 4.8 V rated servos. - 4/12/2012 10:27 PM   
mr_matt



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quote:

ORIGINAL: sidgates

I am surprised how many guys get away with 6.0volts and sometimes more.



Me too.....

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RE: A123 battery too much for 4.8 V rated servos. - 4/12/2012 11:24 PM   
Ad Clark III



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From: Fort Polk, LA, USA
Status: offline 		I have been running same 3321's in stab of Bobcat XL for 10years. A123's for the last four years with Fromeco regulators set to 5.8 volts with no issues. Glad yours happened on the ground.

< Message edited by Ad Clark III -- 4/13/2012 2:15 AM >

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 12:05 AM   
Wclays


 

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quote:

ORIGINAL: jetwash

The jet didnt have any issues with JR Nimh 5 cells prior to switching.

Ken


I believe a fully charge A123 pack is less voltage than a fully charge 5 cell pack. So the question is why did you have problems now?

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 12:40 AM   
flyinfool1



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Status: offline 		I have smoked old servos by switching from a 4 cell to a 5 cell pack.
A 4 cell pack will charge to 6.0V but will drop down to 4.8V in a few minutes under load.
A 5 cell pack will charge up to 7.5V BUT will drop down to 6.0V in a few minutes under load.
An A123 will charge to 7.2V hold 6.6V till it is nearly dead.

The old servos can tolerate a sort duration over voltage but can not take it forever.

Either run a regulator to get down to the lowest rated servo, or use all servos rated for the voltage you are running.
There is no function on a jet that is worth risking a servo failure.


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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 12:44 AM   
jetwash


 

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Status: offline 		Hi Clay, I switched to Futata receivers after buying the 18z. Prior to that, I was using Jr 10x and receivers. Wondering if Futaba receivers is the issue here. On my BVM T-33 changing receiver from JR to Futaba and to A123 battery, my flap servos stopped functioning. Put back the JR battery, all is fine.

Ken

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 12:49 AM   
DAN AVILLA



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From: roseville, CA, USA
Status: online 		I lost two old 8411"s and a 4131 . Old servos do not like the higher voltage on 123's

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 12:50 AM   
jetwash


 

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Status: offline 		Your right. Sustaining 6.6V must be the cause. Easier to install the regulators that changing out all the servos.

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 2:06 AM   
readyturn


 

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quote:

ORIGINAL: DAN AVILLA

I lost two old 8411''s and a 4131 . Old servos do not like the higher voltage on 123's


Dan,

I do believe that the way to go for the older servos is the regulator route as others have mentioned. I was going to just go with A123's straight to the Orbit Power Jack, Futaba R6014, buuuuuuuut better be conservative use the regulator until I get some of the HV servos.

Rick

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 4:29 AM   
Bill Rademacher



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Status: offline 		Well, I am running a lot of planes with A123 batteries without regulators.

But, I have a scale FW-190, and prior to a test flight, I smoked 4 hitec servos inside the fuselage (using ar7000 receiver). One on throttle, the other two on elevator and rudder. I also smoked the retract HS-81 servo.

Everything worked fine on the bench before going to the field. I have since put a regulator in that plane. I already had one on a separate A123 ignition battery.

Not sure what happened, but I smoked them good.

billrad

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 5:17 AM   
Wclays


 

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Status: offline 		I had a project at work that was going to use a Futaba 2.4 system per the customers request. I contacted Futaba about runing A123's without a regulator into their receivers, and was told not to, that a regulator should be used, but a 5 cell nicad was ok. Maybe it has to do with the steady 6.6 volts?

Horizon was ok with a A123 pack with their recievers. So we used a regulator for the project using the Futaba equipement with no issues.

I have no issues with either equipment, I just do what the manufacturer suggest.

I did notice that the DS 168 servos show they are rated at 6.0 volts.

Clay

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 5:47 AM   
jetwash


 

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Status: offline 		Thanks Clay for the info . Let's see, I'm going to need 14 regulators for my jets lol.

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 4:33 PM   
Gixxy


 

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From: Clermont, FL, USA
Status: online 		I contacted Futaba directly about running a 7.4v lipo to their rx after explaining I only needed to send a signal and not power servos directly (giant actuators where being used) and they said no problem. They said it's the servos you need to worry about and not the rx. Flew like that for 10 flights without any issues.

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 10:47 PM   
johnfly


 

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From: Arkansas city, KS, USA
Status: offline 		I have been running zippy and hobbico life 2cell batts for about 2 years "no regulators" using servos = hitec 5625 5645 635hb 5485hb hs81. futaba 148 5101 3001 3002 jr 507 517 d517 and probably a few more but thats all i could come up with off the top of my head..... just throwing this out there to see what if anything comes out in the wash. could it be the sustained higher voltage making it more suseptiable to binding then blowing ???

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RE: A123 battery too much for 4.8 V rated servos. - 4/13/2012 11:45 PM   
rcand


 

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quote:

ORIGINAL: jetwash

Hi guys, Iam switching to A123 batteries on all my jets. The freshly charged A123 batteries burned 4 servos, JR3321 in one of my jet. Fortunatelly that happened on the ground. I guessed those wing servos are rated at 4.8V only. Any one having burned servos using A123 batteries. Iam using Futaba 6014 14 channels receiver. The jet didnt have any issues with JR Nimh 5 cells prior to switching.

Ken


besides myself, I know several people using LiFe batteries with JR servos without any problems

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