Batteries :

The battery of the robot is home made. I have assembled 2 packs of 4 elements each. Each element is Ni-Mh rechargable LR6, 2000mAh. I decided to do it myself because I never found packs with the specifications wanted. The packs are assembled with "heat-schrinkable tubing" found in an RC shop.
The length of the cables that are soldered on the batteries is ajusted. The 2 packs are connected in series; the overall voltage is 9.6V, and the capacity is 2Ah. I made 2 packs instead of jus one, because of implantation problems inside the robot.

Why Ni-Mh? This is a good compromise between complexity and capacity. It is more performant than Pb or Ni-Cd. The Lithium batteries are more performant, but the charging is more complex. The overall power needed by the robot is low: 6W max.

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Autonomy :

With this battery, the autonomy of the robot is 2 or 3 hours

Motors

The transmission part of the robot is very simple. It is a small motor-grearbox, usually mounted on toys. The power of each motor is low (1W), but this is enough.

The mechanics of the motor-gearbox is very poor (lot of backlash and friction). It is therefore a bit more complex to control than with high quality motors, but it is not impossible.

I soldered 2 small capacitors between each plot of a motor, and the case of the motor. This reduces a lot the interferences emitted by the motors.

Tamiya Motor-gearbox

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