I made a 4wd mobile robot with an 4 DoF robotic arm on it and currently in process of designing a power board for my robot. I would like get a detailed road map on designing a power board for the robot. Here is a brief overview of my hardware:
- The robot has 8 joints which each of the motor runs with 12V (stall current: 800mA, nominal run: ~200mA),
- The control board works with 5V (nominal current draw: 500mA, max: 1.5A),
- Overall(averge) energy consumption of the robot is around 6 Watts (max 18Watts).
Here is what I have done so far for powering the robot:
- I am using 2 ncr18650b battery in series with a cheap of-the-shelf battery management system (BMS), so I do not kill the batteries while over-running the robot,
- Nominal voltages of these two batteries are 7.2V where I use one boost converter for driving the motors with 12V and a buck converter for driving the controller board with 5V,
- I have to unplug the batteries when ever I need to charge them (since I do not have a charging circuit for the batteries yet).
Since I was working with the rest of the robot, I just built this battery setup in two days and it was working and enough. Now I would like to focus on developing a professional power management module. Here is simply what I need (need to understand) for designing the power circuit board:
- I would like to power the robot with 2 18650 batteries in series,
- the batteries (in series) should be charged without unplugging (from a 12V DC input port),
- the robot can also be powered on while charging the batteries,
- I would also like to monitor the batteries,
- I would both want to supply 5V for controller board and 12V for the motors from the same battery unit. I encounted a problem with my cheap dump setup which; if motors draw much current from boost converter (12V), buck converters 5V drops. So, I would also like to prevent this happening.
As I am going to through the ICs and datasheet, I assume I need:
- a 2S battery charging IC with a power path management (eg: bq24075) to also power the robot while charging the batteries,
- a 2S battery management IC for balancing/protecting/monitoring the batteries (which are in series),
- a boost converter for 12V,
- a buck converter for 5V,
I am fairly experience with designing circuits but never worked on a power management circuit for batteries. I will appreciate if you give me detailed road map or resources for reading (schematics/articles etc.).