As my robot has increased in sensor and micro controller density, I've had to add batteries. I have currently have three sets: one for motors, one for sensors and one for 2 Arduino Megas and an Intel Edison. Each set can be switched on as needed for software development without having others switched on that aren't needed that just drain batteries. Instead of having to order more again in the future, I bought 8 of them this time. The shipping is more than the harnesses, so I saved money! (as I told my wife)