Welcome to InspirePilots.com

Join the leading DJI Inspire community for free!

Mod values, IMU, etc.

Discussion in 'Inspire 1 Help' started by Mr Phantom, Aug 30, 2015.

  1. Mr Phantom

    Joined:
    Jun 19, 2015
    Messages:
    294
    Likes Received:
    25
    I have been searching for the answer to my question but can't seem to find it. I think i saw it before but can't find it now.

    What is the normal Mod values and all the other values?

    Im about to take my aircraft out for its first flight and want to make sure everything is okay.

    Also is it okay to let the motors spin without the props on? Im doing the battery calibration right now at home and it takes an awful lot of time to get the battery down to 5 percent if the motors are not running.

    And also do i need to make an IMU calibration at the flying location or can i do it at home, and how often should that be done.

    Thanks in advance.
     
  2. Scotflieger

    Joined:
    Mar 29, 2015
    Messages:
    1,240
    Likes Received:
    571
    Location:
    Buckie, Scotland, UK
    The IMU gyro values should be zero while the g values should be +/- 1. The compass Z and Mod values should be 1300-1500. You should do the IMU calibration at home is on a solid flat and level surface. Avoid an area where people or vehicle are moving. The compass should be done in a clear area away from all source of magnetic interference like power cables and reinforced concrete.

    I would not run the motors without the props fitted. They may over speed.
     
  3. Mr Phantom

    Joined:
    Jun 19, 2015
    Messages:
    294
    Likes Received:
    25
    Thanks for your answer.

    What about the X and Y values on the on the compass, mine is currently 20-50 on the X and around 410-430 on the Y.

    So how often should the IMU calibration be done, should it only be done when it says that calibration is required?
     
    #3 Mr Phantom, Aug 30, 2015
    Last edited: Aug 30, 2015
  4. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,862
    Quick correction on the compass mod values. They should be between 1400 - 1600 and ideally as close to 1500 as possible.
    Figures above should be when the ac is at rest and not when airborne/moving.
     
    Scotflieger likes this.
  5. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,862
    I only ever calibrate the IMU after a firmware upgrade or if the aircraft has been subject to a large physical shock.
     
    SqdBoss likes this.
  6. Mr Phantom

    Joined:
    Jun 19, 2015
    Messages:
    294
    Likes Received:
    25
    Thanks. Is it often the compass mod values that are out of range, or is it as common with the other numbers out of range as well?

    Do you people agree with "Scotflieger" that the motors should not be spinning without the props installed? Just wanted some more input.
     
  7. John Alan

    Joined:
    Apr 10, 2015
    Messages:
    225
    Likes Received:
    62
    Location:
    Central IL - USA
    I would NOT spin the motors very long or very fast without a load (prop) attached...
    Quick test only... is my opinion... never to drain a battery... :eek:

    I prefer to use GPS mode and return home autoland... then hold left stick UP to hover it at ~4 feet...
    Ignore all the beeps... no need to cancel anything... let it squawk... it will keep flying with up stick held steady...
    Put battery display on screen and watch it drain away... I look for all cells mostly even and all go red at some point..
    I drain it till it hits just under 3.4v with hover load (under 5% indicated) then ease off up stick and land it gently...
    Soon as the props quit... volts will recover to ~3.5v... that fine... it's ready to cool and recharge to 100%
    Then next time... fly to whatever you prefer then recharge to 50% for storage...
    I'm a "better be down and parked by ~20%" but don't panic if your under that...guy
    I set my warnings at 30% and 10% and left them... you can still fly it against the autoland...

    Others have indicated drain till it shuts off (leave it on, etc)...
    My opinion, bad idea... too far... not needed... may brick one (hurt a cell)...

    I'm teaching the battery board UNDER HOVER LOAD where 3.4v is... as a low limit... 0%
    The following full recharge (charge, turn on batt....charge again) where the full 100% is...
    Your scaling volts to percent charge... it's not rocket science... in my opinion...
    Someone else on here said 3.3v using same process... that's fine...
    I choose not to push MY batteries that low on purpose... my call...

    Just my 2 cents... ;)
     
    #7 John Alan, Aug 30, 2015
    Last edited: Aug 30, 2015
  8. Mr Phantom

    Joined:
    Jun 19, 2015
    Messages:
    294
    Likes Received:
    25
    I appreciate your input. Well i was home and had no chance to fly it at that time, so i just waited like 4 or 5 hours until the craft was down to 0 percent according to the DJI GO app, but i don´t think it was 0 percent since only one of the cells showed red and the others was green and one was yellow if i remember it correct?
    I´m a bit worried if the battery indicator is not showing the correct percentage, that would not be good in a flight.
    I don´t remember the cell voltage but one cell was 0,18 V lower than the other ones.

    Whats the maximum difference that is okay between the individual cells?

    Now I'm charging the battery again, it seems it will be a late maiden flight (around 9 PM), my plan was to take her out on a flight at around 2 PM but i guess the battery calibration process took much longer time than i had expected.
     
  9. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,705
    Likes Received:
    3,862
    Could we keep it on topic please?
    This thread was about IMU/compass mod values.
    There are numerous threads about discharge levels for battery packs.

    Thank You.
     
  10. John Alan

    Joined:
    Apr 10, 2015
    Messages:
    225
    Likes Received:
    62
    Location:
    Central IL - USA
    Sorry to The Editor for derailing the thread into batteryville... :oops:
    I thought the topic was answered well enough in the posts above mine...

    Mr Phantom...
    I would suggest you to recharge each battery till it turns off...
    Unplug and turn it on (like your turning on the drone)...
    Leave it on and plug it back into the charger...
    It will then charge/balance some more till each cell reaches about 4.3v
    It will turn off again at some point...

    Then I suggest you just go fly your machine and be conservative on how low you fly your batts till you have more time to do a proper fly down process on them...

    Enjoy your new machine today... :)
    Worry about resetting the batteries again when your comfortable with it... ;)

    We now return to your normally scheduled Mod/IMU programming... :D
     
    #10 John Alan, Aug 30, 2015
    Last edited: Aug 30, 2015
    The Editor likes this.
  11. Mr Phantom

    Joined:
    Jun 19, 2015
    Messages:
    294
    Likes Received:
    25
    oh just thought its better to keep my questions in the same thread i started, sorry.

    So i guess i will start a new thread for my battery questions right away. Thanks for your help.