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06-29-2014 09:17 PM  6 years ago
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brandonstill

rrApprentice

Palm coast Florida

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Help please.
Battery / charger question :

I'm having a problem that I can't figure out. I'll try and make this short as I can. I've developed a vibration with my trex 450 L dominator. It was flying great and nothing changed before this vibration started. I checked everything I could possibly check This vibration was only happening during normal mode flight. A little in IU 1 and no vibrations in IU2. I could not figure it out. A few days later, I went to try it. Again and absolutely no vibrations during this flight at all. I even lowered the head speed a lot in normal mode and still perfectly solid with no vibrations at all. I was very puzzled. How could this be. Ok, put on another battery and started another flight and this time the vibration was terrible. I was now convinced that my problem is some bad batteries. I'm using the align
6 cell, 1250 mAh, 45 C. I have 5 of these batteries. I've only had them about 6 or 7 months and have only charged each of them probably about 10 or 12 times each. The problem is I have left them fully charged at all times even when not in use. I've now learned is not good but I've also done this with many 3 cell batteries and it has never hurt them enough that I could notice. These 6 cell batteries have no puffiness at all and after each flight, all cells when checked are very close and most cells in each battery are exactly the same. But it must be the batteries because I have charged them all up and the same battery produces no vibrations and the other 4 batteries produce the vibrations in my heli. I have no way to check the internal resistance of these batteries but everything sure looks good. I'm wondering now if it could be my charger. I'm using a bantum bc6 that I've used for 2 years with no problems. I now have ordered a power lab 8. Just waiting to get it. I think someone told me once that a battery can look good with close cell voltages but once a load is put on it, it can drop from like 95 % to like 30 % with a load on it. When the battery is bad. Has anyone ever had this kind of issue ? Or know what is going on ? I truly appreciate any helpful knowledge.

Thanks a bunch.
Life is good. Better with a bunch of Heli's
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06-29-2014 10:39 PM  6 years ago
AWittleWabbit

rrElite Veteran

O.C., CA

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There's no way your battery is causing vibration. Maybe adding or subtracting mass changes the resonant peak.

Back to your vibration. This assumes you've checked head and all rotating parts for secure fasteners.

For tracing down vibs I suggest taking all the blades off. Run your Dom bladeless on the ground in Nor, IU1, and IU2.

If no vibs are present, put the tail blades on and repeat. Be careful now that you have tail blades on.

If no vibs are present, double check the balance of your main blades.

If mains are balanced, replace the spindle and main mast.

It's not commonly mentioned but check your torque tube for runout. Pull the tail boom off the Heli and turn the tail rotor. See if it wobbles. Then pull the torque tube back out and flip it around, check for a wobbly torque tube again.

Let me know what you find.
Heli-itis sufferer.
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06-29-2014 11:44 PM  6 years ago
brandonstill

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Palm coast Florida

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Thanks Wabbit, I could go into all I've done to correct this but it would take a while. I'll just ask why do 3 of my align batteries produce this vibrations and 2 of them do not. Perfectly still with no vibes. With the 2 batteries that produce no vibes when flying, I've even turned down my head speed very slow and still no vibes at all. Most vibes don't come and go just because you change out a battery. I probably didn't make my question clear. Sorry about that.Life is good. Better with a bunch of Heli's
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06-30-2014 01:48 AM  6 years ago
BobOD

rrElite Veteran

New York- USA

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Is the head speed changing with different packs?
What ESC?
Are you using governor?
Team POP Secret
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06-30-2014 01:51 AM  6 years ago
wrongler

rrProfessor

Brewerton, New York

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I would also check or replace the blade dampers.Bill Whittaker
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06-30-2014 02:45 AM  6 years ago
jschenck

rrProfessor

La Vista, NE.

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I'm thinking that your battery mount should be looked at. Perhaps the batteries causing vibrations are hitting something or are loose in the battery tray system somehow.
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06-30-2014 03:54 AM  6 years ago
brandonstill

rrApprentice

Palm coast Florida

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It seems the headspeed is slowing down but I can't be sure. I've not checked it with my tach. But with the good batteries, I've really slowed down the head speed a lot and still no vibrations. I've not thought about the dampers, I'll take care of that. All batts are solid to the battery trays , taped on good and Velcro straps around them.Life is good. Better with a bunch of Heli's
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06-30-2014 04:16 AM  6 years ago
AWittleWabbit

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O.C., CA

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If your running throttle curves, maybe the peppier lipos stay out of the rpm range of the vibration. You mentioned it goes away in idle up. Are you using really low head speed?Heli-itis sufferer.
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06-30-2014 05:33 AM  6 years ago
BobOD

rrElite Veteran

New York- USA

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My thought was that a difference in the IR of the packs is interacting with the esc operation somehow. Would need to know more about your setup.Team POP Secret
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06-30-2014 09:14 PM  6 years ago
es1co2bar3

rrKey Veteran

Atlanta GA,

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Make sure you have the bearing fitting in each main blade Grip
Check the Dampener make sure they not too hard Lube them up with little grease,.... make sure the main shaft spin freely in the center bearing them bearing can be bad and feel like they're grinding.
make sure airfoil on main Blade is intact. make sure motor shaft
is not bend low Rpm you wont detect VIB on bent motor shaft but higher
RPM you'll.

The battery should never be a facture no matter how it impact the COG}.....
make sure you not using mix match Tail blade.

make sure main bearing block isn't loose between frame and all 4 screw is lock tight.
I was waiting on some honey but there aren't no Queen bee,
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