A disaster response 4WD light following rescue rover with an in-built battery monitoring system

Connect two LDRs in pins A0 and A5 of your Arduino. And connect the three LEDs in pins 2, 4 and 8 respectively, to measure the battery voltage, connect the +ve pin of your battery to your Arduino's pin A3, via potential divider (refer to the circuit diagram of Alnitak). And connect or change the pins of the motor driver according to your circuit (all the pins connected to the motor driver must be PWM).