4000 mAh Battery – Phantom FC40
The required modifications to the a/c were carried out by two qualified electrical and mechanical engineers.
We thought that the FC40 battery arrangement is a bad design for any battery. Considering the Phantom 2 battery modification by DJI we know that they have acknowledged this and rectified the problem.
To accommodate the 4000 mAh battery the door hatch nearest the hinge required the bottom lip to be level with the battery supports inside the a/c. This was done using a Dremmel cutting disc and then to finish off, a fine file. The battery fit is tight and care should be used in insertion. (No comment here)
Next, we examined the possibility of cable failure within the aircraft with placing the cables and battery inside. Various components were placed under strain and considering the MBR of the cable, (See
http://uk.ask.com/wiki/Bend_radius?lang=en
For more explanation)
It will happen that the cables fail due to high resistance and / or fatigue after numerous battery insertions – the most vulnerable point being the rear of the XT60 socket and plug. Together with this there could be additional strain exerted on the cables themselves and the soldered joints on the PCB.
We consider it an important safety requirement to place the cables and connecters to the outside of the a/c.
See:-
viewtopic.php?f=20&t=15368
An opening on the hand side of the hatch door is provided to allow the battery leads exit point.
We disassembled the body shell and cut a notch on the body near the base of the arm. It is advisable not to make the cables exit point a tight fit but to allow room for the cables to have some movement in and out with two winds of electricians tape where the cables exit the body to reduce cable fatigue. The cables are secured to the body inside with hot glue to reduce the strain on the soldered joints on the main board.
Fitting the battery connector to the outside of the a/c is more convenient and safer than the ‘designed’ way and we recommend that this modification is effected by all FC40 owners.
The following U-Tube clip describes the method above :-
https://www.youtube.com/watch?v=okVp4LW1BA0
However, some of you will prefer the following method which is more simple and quick :-
https://www.youtube.com/watch?v=bGNIuN9oK80