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Multiplex Easystar, new battery, low motor power

GeteburgGeteburg Club Members Posts: 3

I've got an old version of Multiplex Easystar, probably 5 years old or so..

I've had a LRP lipo, 7.4v, 1900mah, 25C battery which I forgot in the plane one day and of course the battery went bad. With this battery the plane was flying just fine.

I've bought a Turnigy 7.4v, 3300mah, 30C and I've charged it and it just doesn't feel the same power.

When I throw the plane, it just can't go up as there is not enough power.

The new battery is about 100 or 150 grams heavier so that alone can't be the reason, or can it be?

I know when the plane was on the ground with the LRP battery and if I set it to full power the plane almost moved on the grass.

With the new battery it doesn't. Even the air behind the prop doesn't feel as strong as with LRP battery.

Any ideas on what could be the reason?

Motor is: Permax 400 6v with BEC Elite Aero 27A.


  • WTWUKWTWUK CornwallClub Members Posts: 13,367 ✭✭✭
    Have you removed the prop at any time and replaced it the wrong way round?

  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    "The new battery is about 100 or 150 grams heavier so that alone can't be the reason, or can it be? "

    It most certainly will make a very noticeable difference to something like a light little Easystar. If you're saying it can't even stay airborne at all though there is probably more to it than that though. What WTWUK suggested is a very common mistake people make on pusher prop models for some reason too. Why go so much bigger anyway? Those little buggers would usually stay up almost forever if you kept them light.
  • GeteburgGeteburg Club Members Posts: 3

    Prop not changed or removed, after the battery died, I order new one right away so in the week without battery, prop stayed on.

    Yeah, it will make a difference for sure if there is a bigger battery. However, so much difference that it cannot fly? Its like a paper plane now, I throw it with full power and it just glides as much as it can down to the ground, imagine throwing a paper plane from A4 paper. :)

    Maybe it is too heavy now. Best thing to buy the same battery as I had before. I still think that there is something else going on. Could the motor be damaged during the night when the battery was connected?

    Hard to explain but even by the sound if I hold the plane in my hand it just doesn't feel as powerful as it was.

    Battery is battery, right? So there is no way that one battery would have less power when fully charged.

    I will buy a new old battery,give it a try and will report back.

    Any suggestion on a good battery? Are LRP batteries any good?
  • WTWUKWTWUK CornwallClub Members Posts: 13,367 ✭✭✭
    Can you measure the voltage of the new battery cells at all? Sounds like maybe you have a dud cell ...

    WTWUK2015-10-10 18:24:07
  • GeteburgGeteburg Club Members Posts: 3
    Okay, I feel embarrassed now.. :)

    The problem was that the motor shaft was simply not gripping the prop and after certain power and prop drag, well, you know what I mean :)

    Put some super glue on prop and shaft and we now have full power :)

    Must say that the battery is a bit on the heavy side. Will probably buy a new one, lighter one. :) You never have too many batteries right? :)

    Thanks Sawdust and WTWUK for the help.
  • WTWUKWTWUK CornwallClub Members Posts: 13,367 ✭✭✭
  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    Don't worry, I'm far too embarrassed to tell you about some of the supremely dumb things I've done. Glad you found the main problem, and happy to have helped even if only a tiny a little bit   image .

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