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P2 Cheap china battery when in NAZA mode

Discussion in 'Phantom 2 Discussion' started by pete, Jun 4, 2014.

  1. pete

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    Hello, can anyone share his experience(if any) with some other LiPo's,
    I would like to squeeze this one inside :)
    http://www.hobbyking.com/hobbyking/stor ... _Pack.html


    I know about banggood 80ish $ copy of DJI intelligent battery, but that is too much also, and some have reported shutting down motors in mid air,
    because those(and original DJI ones) have circuit inside of them that breaks connection to exposed pins when charge is complete or battery is drained,
    so it can happen in air too...
    and besides that.. it slows down charging rate.

    but if phantom 2 gets switchet to NAZA mode in GUI, it can work of any Lipo as long as you make a connector,

    I am planning to do it, but would like to know dimensions of battery tray and if someone has done it already?
    (my P2 is on its way still so I cant measure it :( )
     
  2. rilot

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    I don't think it can. If it could, we'd all be doing it.
     
  3. pete

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    I don't speak chinese...
    http://h5.m.taobao.com/awp/core/detail. ... 7980963829
    .

    But it looks like it is possible to solder connectors to stock battery cap and plug lipos in it.
    good if they can be charged on regular charger and only plugged in that cap.
    with voltage alarms disabled. Monitored via osd or similar in flight....
    Maybe somene knows more..
     

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  4. tom3holer

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    The voltage alarms are active in Naza mode so yes you would have to use the head of the battery and incorporate the built-in circuitry. This means you would have to get a bad battery and remove the case.
    No way do I think this is a viable workaround. Too much to loose on a homemade battery replacement.

    There is a new alternative being offered for about $80 that looks very nice and just like the original with I believe 5600 mah.
    I can't seem to find it now but it was mentioned in a thread here somewhere.

    Tom
     
  5. ElGuano

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    There are some caps being sold that can be used with regular lipos, but I don't think anyone has described in detail how they work.

    People have stripped down and removed the cells from a DJI smart battery and have examined the way the smart circuitry work. Normally, you can't just plug and unplug new cells in, because the smart chip remembers and counts current from last charge to report the battery capacity remaining % to the NAZA. If you swap out a drained pack with a full one, the smart chip will still think that new 12.6v bat is at 40% until you cycle and charge it. Whether the clone caps account for this, simply spoof a 100% full pack (what would that do to the low voltage alarm, auto-land or battery protection circuit?) or otherwise is simply not known. There's also the chance that a firmware update from DJI will require a password or encrypted handshake with the battery circuit, which it currently does not....so a lot of questions, not a lot of answers. Maybe some enterprising soul will take the plunge and test it out, but for those who don't want to be the guinea pigs, I'd wait for that to happen before jumping aboard...
     
  6. tom3holer

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  7. ianwood

    ianwood Taco Wrangler
    Staff Member

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    ElGuano, are you sure the battery percentage algorithm is derived from the way the battery is draining over the duration of the flight? It would seem too easy to just base it on voltage. Do we know if this is determined on the battery controller itself or by the Naza?

    BTW, I saw you got some of pawelsky's Teensy shields. Was that for your P2? I have mine but haven't found any time to install it yet. I am curious to see if there is any communication from the battery controller to the Naza that is unique to the P2. I haven't found anything in the OSDII DAT logs but it is probably only capturing specific payloads.

    And, OP, I don't think the mode (NazaM/Phantom2) has any influence on the battery control.
     
  8. ElGuano

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    Hi Ian,

    Tiagobaracho actually did the test, he removed the stock 5200mah cell pack and soldered on a smaller pack. The way the battery pack reported charge remaining wasn't consistent with simply reading 3s or cell voltage, which is how I thought it would be done.

    I'm sure there is can communication between the SMB and Naza, the transceiver is on the board and the Phantom-Naza won't arm without EXP, which on the p2 should be exclusively Can. I haven't done the logging to find it yet, though.

    I see where you are going with this, sending a spoofed battery msg and regular heartbeat to the Naza over can would allow any battery to be used! But that's something I probably won't broach; I'm pretty comfortable with the idea of snooping the bus for data, but injecting data into the stream to the Naza is a scary beast. I'm not even sure I want to send pmu/iOsd heartbeats to the canBus if logging in flight!
     
  9. ianwood

    ianwood Taco Wrangler
    Staff Member

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    That and maybe blocking the auto-descend if possible. I know what you mean about injecting messages. It will be a while before I get the courage to do that! BTW, you beat me to the neo-pixel mod!