Sluggish Servo Movement

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Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:04 pm

So I pulled out my fully charged Primo this past weekend. Upon a ground check three servos are not only sluggish but barely moving at all. When I throw the sticks the control surfaces either move really sloooooooooooowly or not at all. I have not flown this plane in a while, but I have never experienced this with planes, I've not flown for years... Battery is charged and 2.4 is bound to the plane. I mean is it on the rx side, servo grease, wire connections?! Before I start tearing everything apart and looking, has anyone ever experienced this. I searched the threads but didn’t find anything. If anyone has some advice or can point me at the right thread, I’d appreciate it. Thanks
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:11 pm

I'd suspect the battery. You sure it's still good? Just because it shows full voltage doesn't mean it still good. Could also have a short causing issues.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:17 pm

Thought about that, 5 servos, three are sluggish and 2 move as normal I guess could still be the case...
Last edited by c_locklair on Tue Sep 25, 2012 2:18 pm, edited 1 time in total.
Yes, I do mixing with certain models: balsa, monokote, dirt, and grass...and now WATER too!

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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:18 pm

c_locklair wrote:Thought about that, 5 servos, three are sluggish and 2 move as normal


What kind of battery?
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:20 pm

Unplug the servos one at a time and see if it goes away. I had a servo smoke and it caused all the rest to move slow.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:24 pm

rcaircraftnut wrote:Unplug the servos one at a time and see if it goes away. I had a servo smoke and it caused all the rest to move slow.

x2!
I would look at battery first, then unplug all servos and try one at a time
one can drag the whole bus down

if you have a slow one, try oiling it,
usually a slowing down servo is a failing servo,

there iare only 2 kinds of servos, failed servos and servos that are gonna fail!......someday.....well, not really :mrgreen:
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 2:52 pm

chumley wrote:
c_locklair wrote:Thought about that, 5 servos, three are sluggish and 2 move as normal


What kind of battery?


Hydrimax 6v 1600 - may be time for a replacement. I'll swap out when I get home. Start with the easiest first right... :roll:
Yes, I do mixing with certain models: balsa, monokote, dirt, and grass...and now WATER too!

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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 3:05 pm

What radio you running?
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 3:07 pm

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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 3:34 pm

c_locklair wrote:
chumley wrote:What kind of battery?


Hydrimax 6v 1600 - may be time for a replacement. I'll swap out when I get home. Start with the easiest first right... :roll:

There's your problem. Typical NiMH that can't maintain a voltage under a load.

Put a voltmeter on the battery output and measure the voltage while the servos are idling, then measure it again while moving the servos. I'm betting the voltage is seriously dropping under a load. Running this test was the final straw that scared me away from using NiMH batteries in any plane. All of them have since been replaced with either A123 or LiFe.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 7:07 pm

McDDD is right -- that'll be a pack made from AA cells and they are *crap* at delivering any decent amount of current, especially once they start getting old.

The only other time I've seen servos run slow like that is when I've had a few knocks on some Hitec coreless servos. This can cause the wire rotor to deform and rub on the magnets. That slows the whole motor down and causes the servo to draw lots of extra current as well.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 7:19 pm

I always thought the HydriMax packs were junk. Any NiMH packs I use all come from NoBS Batteries. These days it certainly looks like the A123 packs from WWRC are the way to go.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 7:57 pm

+1 wwrc ftw.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 10:35 pm

I really do need to run the a123s. What do you guys recommend as a good batt. pack and what do you need to charge them?
Yes, I do mixing with certain models: balsa, monokote, dirt, and grass...and now WATER too!

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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 10:45 pm

:thinking:


Looks like most recommend the WWRC A123 :wink:

Pretty sure most chargers that do Lipo will also do the 123's,... might be wrong tho.
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Re: Sluggish Servo Movement

PostPosted: Tue Sep 25, 2012 10:46 pm

c_locklair wrote:I really do need to run the a123s. What do you guys recommend as a good batt. pack and what do you need to charge them?


You will need the 1100 for the Primo. He has the FMA chargers that work great. In the combo deal you get the Batt, Charger and a charge lead. A great deal and worth every nickel.

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Re: Sluggish Servo Movement

PostPosted: Wed Sep 26, 2012 1:18 am

Got an A123 2300 and a cellpro modified by factory to do A123. Chargers have to have a function for A123, some of the newer ones do them all.

I'm not totally against Nimh batts. Been reading about them and they don't like being partially drained and charged again, don't like being discharged hot or charged hot and really don't like having their voltage reversed. Any of this type of usage can cause one or more cells to drop voltage faster than the others at one point or another, even though none of the cells are really bad. The method given for conditioning Nimh cells in this state is to discharge the pack to .9 volts per cell at a very low rate (like .5C or less) to get all of them to dump without reversing voltage badly in the first cells to dump. Then charge them up at 1c or less and repeat at least two more times. It's a slow process. I've been using Nimh batts in my TXs. They seem fine for that but do seemed to lose capacity after a year or so. I have done the above procedure and it does seem to restore them to better balance, not new capacity but give even voltage for long periods again. Still a slow process and I don't trust them for airborn packs for the above reasons and for the fact I haven't seen any Nimhs, even good sanyos designed for high discharge that can be relied on. For airborn packs, I am going to A123s on all of them. I've still heard very few reports of A123s going bad despite some real rough treatment. :tu:
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Re: Sluggish Servo Movement

PostPosted: Wed Sep 26, 2012 3:34 am

c_locklair wrote:I really do need to run the a123s. What do you guys recommend as a good batt. pack and what do you need to charge them?

Support a bro and get a pack (or two) from WWRC

As for chargers -- any of the modern chargers will handle the A123/LiFePO4 chemistry.

I just use a Turnigy Accucell 6 and it works perfectly fine -- no problems at all.

If you get a WWRC pack you can charge at up to 4C (4.4A for the 1100mAH pack) although I prefer to charge my A123s at 2C, it's kinder on them.

If you get a generic LiFePO4 pack then you should stick to 1C charge rate.
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Re: Sluggish Servo Movement

PostPosted: Wed Sep 26, 2012 6:11 am

I too use the accucell 6, and I crank it up! I love me some a123, won't use anything else. I lost a plane in the woods in the spring. Found just about everything, except for the battery and rx. Well, found em both about two weeks ago. Rx is shot, but guess who got cycled a couple times and has been just fine? Yup, a wwrc 1100 pack.
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Re: Sluggish Servo Movement

PostPosted: Wed Sep 26, 2012 6:26 am

Sorry SU. Totally overlooked your first post with advice...scrolling on the droid. Thanks for all the comments. I'll start with all the aforementioned advice and drill my way down to the core which may ultimately be the batteries. Any rate gonna make the battery move.. I hope one year I can make that drive up to a PB and meet some of you guys..work makes it tough tough...maybe next year. :rockon:
Yes, I do mixing with certain models: balsa, monokote, dirt, and grass...and now WATER too!

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