It only monitors total battery voltage so only needs one resistor. The other wires from the balance lead go nowhere on the board.
Be VERY careful that you connect the battery positive wire to the correct pin (red wire). If you accidentally connect it to earth pin (where the black wire is shown), you'll produce a short-circuit across the APM board which will vapourise earth tracks and possibly destroy the board.
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I'm assuming you have an APM1. You only need to put in one resistor as per this page:
http://code.google.com/p/arducopter/wiki/AC2_Current
It only monitors total battery voltage so only needs one resistor. The other wires from the balance lead go nowhere on the board.
Be VERY careful that you connect the battery positive wire to the correct pin (red wire). If you accidentally connect it to earth pin (where the black wire is shown), you'll produce a short-circuit across the APM board which will vapourise earth tracks and possibly destroy the board.