Turtlebot 3 BMS?

Howdo, I’ve just built a Turtlebot 3 burger and I’m already finding it a pain to charge as I’ve been spoilt by having a charging port on the robot I scratch built. Has anyone added a battery management system or swapped for a different battery to make it easier to live with please?

If there’s prior experience to follow I’d prefer that to starting from scratch, otherwise I’ll just use a 3s BMS from another robot I have going spare.