I’m pretty new in the robot business, so sorry for the newbie questions…
Questions:
I’m not sure how/where to plug the battery pack, as I want only one battery to power eveything. Note that the battery pack has only an Arduino Compatible DC2.1 Power Jack.
Do I need some kind of voltage converter to power the Arduino and the motors at the same time?
Since your battery pack has a barrel connector compatible with the Arduino, you can connect it directly. This will power the Arduino board. Make sure to power the L293D motor driver logic from the regulated 5V but to obtain its Vdd (motor power) from the Vin instead. This will somewhat prevent motor signal noise (when they start/stop/stall) on the Arduino board and also prevent damage to the on-board 5V regulator.
The voltage provided by the LIPO battery you chose would provide all the power required to the Arduino. It has an on board converter which will take care of transforming the 7.4 V into 5.0 V DC. The main problem you will encounter is that this battery pack is 7.4 V whereas the motors used in the rover kit (Tamiya Twin-Motor Gear Box) cannot handle such a high voltage. This kit is meant for a 3.7 V DC LIPO battery pack, usually by using the DFRobotShop Rover Mobile Robot Shield and the 3.7V, 2000mAh, 5C LiPo Battery.
The battery pack in itself is fine for your purpose. It has a voltage that is too high for the motors you will drive with it though. One option is to ensure that the duty cycle of the motors is under 50% at all times so as to give a lower voltage to the motors and therefore prevent damaging them. This is not a fail-proof method and is not usually recommended but if you do not wish to change or purchase more parts, this is one possible solution. We also recommend that you obtain the battery charger for your LIPO battery pack since it cannot be charge without a special LIPO charging circuit. It is available here: 7.4V Lipo Battery Charger.
