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Battery communication solution

Discussion in 'Phantom 2 Vision Discussion' started by spazmodic1, Dec 20, 2013.

  1. spazmodic1

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    Hi all,

    Just though i would put this out there.
    Frustrated by the continuous battery communication errors i kept receiving. I decided to do something about it.

    after measuring the depression of the two communication pins when the battery is installed with a set of vernier calipers, I discovered one would get about .5mm of depression out of a total of 3mm. ie. when the pins touch the pads on the battery, they only get pushed in .5mm (on my PV anyway) So there must be some sort of design flaw there.

    So i could only assume the errors would go away if there was better contact.
    I acquired some small solid brass bolts from the hardware store. Thin brass rod would be better.
    I basically grinded off a bit of the thread on a bench grinder to resemble something like a bit of rod. I then cut a length of about 3mm with a dremmel. i was then able to hold this tiny piece of brass and grind it down to 2.5mm.
    I then soldered these two little brass lugs i had made onto the pads on the battery. It is a little fiddly as you can see by the burn marks of the soldering iron so it helps allot if you have steady hands and some fine tweezers to hold the lugs.
    I have taken it for two test flights and have not received an error yet.
    It isn't quite the same as the gold plating of the original pads but im guessing it should maintain a reliable connection.
     

    Attached Files:

  2. garygid

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    Location:
    Laguna Hills, Orange county, CA 92653
    I am thinking of extending the pins in the P2V, to avoid
    having to modify each battery.

    Has anybody tried to get the cap off of the battery?
     
  3. LeoS

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    Thanks for sharing the info (and hack), spazmodic1 !

    Can you tell me how did you measure the depression of the pin (.5 out of the max 3mm)?
     
  4. spazmodic1

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    Yes sure,

    For the young players out there i am using a set of vernier calipers which is a tool that will accurately measure depth, length, ID, OD. A very handy tool. I could not add a pic of em because can only upload 3 pics.

    So without trying to explain it too much i took the measurement in the 3rd pic which was 1.58mm (sorry uploaded files in the wrong order).
    Then took the measurement of the 2nd pic which was 8.40mm
    So 8.40mm-1.58mm = 6.82mm which is how far those metal pads go inside the PV from that face where the PV and the battery meet.
    So now in the 1st pic i am measuring from that face to the pins(without pressing them) which gave me 6.20mm

    These measurments are slightly different from the original ones but now i have these numbers from that reference point/face i just go 6.82-6.2= 0.62mm
    So the depression on the pins is 0.62mm

    Hope it healps. Sorry if its hard to understand
     

    Attached Files:

  5. myvrodrocks

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    Location:
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    Anyone ever had the first Tomtom rider for motorcycles? The charging pins on the back had this same problem. Vibrations from the bike caused the spring loaded pins to wear holes in the contacts and it wouldn't charge anymore...
     
  6. Richhealth

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    Absolutely awesome. Love to see someone problem solving, and then sharing. Thanks for taking the time. Please do keep us posted on more issueless flights.

    Rich
     
  7. spazmodic1

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    No worries, iv have taken too much from all these forums and never return the favor.
    ill keep you updated.
     
  8. garygid

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    Location:
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    A summary of the measurement process.
    If you post your measurements, please include the battery serial number.

    One makes three measurements: A and B on the battery, and C on the P2V.

    1. Battery cap edge, to rim around the contact dots (the 2nd pic) A = 8.40mm
    2. Battery rim around the dots, in to the dots (the 3rd pic) B = 1.58mm
    3. P2V outer face to pin tips (the 1st pic) C = 6.20mm

    Then, the pin Depression (D) is calculated:
    D = A - B - C = 8.40 - 1.58 - 6.20 = 6.82 - 6.20 = 0.62mm of Depression

    In my opinion, for the Depression number...
    Anything over 0.50mm is not bad, but about 1.00mm might be better.
    Under 0.50 is poor, under 0.10 is bad, and 0.00 or negative is right out.

    The A - B = 8.40mm-1.58mm = 6.82mm is how far the battery's metal
    dot-pads are inside the PV from that face where the PV and the battery meet.
    C is from that face to the pins (without depressing them), for C = 6.20mm.

    Great, I will try to measure my two batteries and the P2V this evening
    (they just arrived late yesterday).
     
  9. garygid

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    Location:
    Laguna Hills, Orange county, CA 92653
    I just measured my P2V battery pin position at C = 5.40 mm.

    Note that my P2V's pins are 0.80 mm closer to the contact
    discs on the Battery (unless I measured incorrectly).

    I measured again and got 5.58 mm, or 0.18mm further in.

    Battery 1: A = 8.34, B = 1.47, so D = 1.47 to 1.29 mm, which should be good.
    Battery 2: A = 8.55, B = 1.64, so D = 1.51 to 1.33 mm, which should be good.

    It appears that the dimensions of the Batteries are reasonably
    constant, and that the position of the P2V's plunger contact pins
    is the variable. Some more measurements would be helpful.
     
  10. spazmodic1

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    Well i can safely say the mod has been a compete success. It has been about my 5th flight since the mod and i have not received 1 warning about an invalid battery. So im quite pleased about that. There is nothing worse than that bloody message popping up all the time while your flying.

    So even though the pins do make contact (without mods) im guessing the lateral vibrations coming from the props cause the pins to loose their contact due to the lack of holding strength of the springs in the pins.

    garygid i was also thinking about modding the pins, Im not sure if you can access the springs for the pins at the rear of the connector. I did want to look but its a big job because you would have to take out all the esc's, mainboard, motors to access that connector and have a good look at it. My idea was to strengthen the springs some how to make them stiffer. Either that or i guess you could try to extend the pins some how. The only problem is you risk damaging the connector and i imaging getting a new one would not be easy and of course time consuming.
     
  11. kingcat200

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    Hi
    Despite loosing my first PV2 on its first flight due to what was to become a very well know issue Ie invalid Battery ( Before Firmware Fix) . I have decided to dip my toe's in the water again,the Battery offer did help in the timing.
    I manged to get four flights in yesterday with no warnings yet.
    Thanks to some work and lateral thinking by forum members here and elsewhere it wold appear the problem is the pins only just making contact ( yet to measure mine).
    I have made the decision should I start getting these warnings I am going to elongate the holes in the connector block mounted on two stern post and re mount 2mm or so further towards the Battery pack ie physically move the whole connector block closer to the Battery pads.
    I would also see this as a permanent fix for DJI.
    Who knows they may have already done it by re-positioning the hole positions during manufacture . I hope so as my second PV2 is the latest shipment.
    I will measure distances and report further.
    As I say I will only carry out this mod in the event of warnings.
    I just wondered if anyone else had considered or indeed carried out this mod.
    I also wonder if the issue was caused by using the larger 5200 battery's in production models as all the Beta version videos I watched had smaller batteries about 4700 i seem to remember.

    Merry Christmas to all
     
  12. spazmodic1

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    kingcat this is a good idea, i had a look at mine and you have about 1.5mm to play with before the connector butts right up against the battery which should be plenty to eradicate the problem. It just means tearing out all the internals of the P2V to access the connector.
     
  13. kingcat200

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    Hi Spazmodic thanks for the vote of confidence.
    I am away until after the holidays so won't be able to pursue the idea unti then.
    Howeve as soon as I get the chance I will get the vernier out and have a measure up and report here.
    As I say a little bit of me is hoping DJI might have already done it on on latter production models
    I am pleased your mod has worked for you and also confirms what the fundamental problem is.
    Having had the top of my Classic a few times now for various reasons I am not to daunted by the disassembly required.
    Seasonal Greetings to All