250 pro sometimes out of control

Discussion in 'Walkera Runner 250 Pro' started by aerobat77, May 7, 2018.

  1. aerobat77
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    aerobat77 New Member

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    hey gents !

    i,m new here and first a big hello to everybody ! i,m living in germany and found this great forum , hope to get some hints on a strange issue i had on my brand new 250 . i collected one or two dozens flights on it , up to now crash free flights .

    today i made on a free area somekind of a advanced testflight , forcing it to high altitudes , tested the rth from distance ( works nice ) as well the other modes . expecting low battery soon i started to walk back from the free area where i started the copter to my parked car about 200 feet away and flew the drone slowly infront of me during the walk . ( maybe at 30 feet altitude ) .

    shortly before i reached my car the battery warning went off and i lost control !!

    i tried to lower and land the drone but it tried to climb by itself . gps on , gps off , nothing worked ! i finally let it go and it climbed by itself to about 60 feet and started by itself flying back again to the starting point , hovered above this point for some time and then lowered and landed . i expected it will crash every second due to a complete drained battery but had luck .

    on previous flights i was able to control and land the copter when low battery alarm went in , this time it even in manual mode did not responded to inputs .

    can it be that a 250 pro will fly back to starting point when low battery alarm starts AND it is not in vicinity of the starting point at this moment ?

    best regards

     
  2. bjr981s
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    bjr981s Moderator Staff Member

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    At some point you lost your TX link to the 250. It then executed its Lost TX routine of doing a RTH.

    Do Not. I repeat do not think that the alarm means you should land now. It does not. It is a "battery is now self destructing" warning.

    This is a last minute warning that you have over discharged your battery and am now damaging the cells.

    You need to land as soon as the battery reads 3.6V per cell 10.8V. Do not discharge below. Either use the FPV Telemetry or set a flight timer on the radio.
     
  3. aerobat77
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    aerobat77 New Member

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    i tried fail safe rth by intentionally switching off the radio and in this case all the orange directional lights illumminate and the copter gives a loud beeping . this was not the case here .

    regarding battery : i thought the battery alarm tells you : land now without delay but not 'battery is destructing' . i have the timer on always as a reference and at this flight it landed at 13:42 ... not hood
     
  4. bjr981s
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    bjr981s Moderator Staff Member

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    They are Lipo Batteries. They self destruct at voltages above 3.9V and below 3.6 V. The higher and lower the faster.

    This is why you don't store the batteries fully charged. You store them at Storage Voltage 3.8 V per cell.

    They are only stable around the Nominal voltage. 3.7V. Don't charge batteries the night before you fly, charge them just before you fly. And always return them to storage charge of 3.8V when finished.

    Anything longer than about 8 Minutes in a flight is shortening the life of the battery.
     
  5. aerobat77
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    aerobat77 New Member

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    ok thanx , will keep a closer look on the battery !

    you ever heared the 250 pro will execute a rth without a chance to manually override iz when the battery runs low to alert AND you are at this moment at a greater distance from the starting point ? that appears to happened to me .

    does the copter measure its distance from the tx radio ?
     
  6. bjr981s
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    bjr981s Moderator Staff Member

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    If you do not have fixed ID set in your radio once you lose the link it stays lost. That is the benefit of Fixed ID. It will always auto reconnect.

    So you can never override as the link is down and it does not detect you using the radio.

    You can only override a Manual RTH (Mix Switch) as you still have a valid link to the aircraft.

    It does not care where the TX is at any time. Home is Home.

    It has no idea where the TX is located. Only the Home point.
     
  7. aerobat77
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    aerobat77 New Member

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    ok... very useful inputs and i tried the following : i searched how to do and applied a fixed id to my copter .

    made a testflight where i walked away some distance from the starting point and forced the battery running into low to look if it will make a forced rth without override .

    the copter takes one shake in the moment low battery kicks in but it stayed under my control and i was able to land where i wanted to .

    no idea if a fixed id is the key to this but i will keep the fixed id setting . great help and hints here !!!
     
  8. bjr981s
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    bjr981s Moderator Staff Member

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    Not a valid test. Try it again and this time turn your radio off.

    When this happened to you it had nothing to do with low battery. You lost the tx connection to the model. That caused the RTH. And the radio did nothing as it was disconnected so you could not abort.
     
  9. aerobat77
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    aerobat77 New Member

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    maybe i miss what you mean with this post but are you saying my forced rth i described in my initial post of this thread has nothing to do with a low battery ?
     
  10. aerobat77
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    i tried one time fail safe rth and with switching the tx off inflight all the orange lights on the wings start flashing slowly and the copter beeps - even after landing . that flashing here never happened
     

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