I bought a "Multi Battery Parallel Charging Board For DJI phantom3" on ebay, and I soldered on a deans female connector for connecting it to my iMax B6 charger.
Since the Phantom 3 battery is intelligent and has its charging circuitry in the battery itself, the iMax will just work as a voltage booster with an output of 18V. This is 0.5V more than the DJI charger provides but it seems to work. So anything that can output >3A ~17.5V should be able to replace the iMax.
- Connect iMax input to car cigarette connector
- Connect iMax output to the multi-charging board.
- Connect the Phantom battery to the board
- Choose Pb charge, 5.0A, 18.0V (9P)
- Turn the battery on right before long-pressing start on the iMax (by using the short-then-long-press sequence on the Phantom battery.)
- When the battery is full it will say CONNECTION BREAK, but this is because the intelligent battery circuit will disconnect itself when fully charged.
In the next version i will be using a cheap boost converter from ebay, like this: http://www.ebay.com/itm/150W-DC-DC-Boost-Converter-10-32V-to-12-35V-6A-Step-Up-Voltage-Charger-Power-/171907240597
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