Power Distribution

Power

The power source for kupe will be one or two 12v batteries. Currently I am using one 12V 7Ah lead-acid battery. I have enough room to replace this with a 14Ah device or use two 12V 7Ah batteries instead. These could be connected in parallel or series if I decide to move to 24v drive and change the motors.

I will stick to lead-acid batteries for now as they add extra weight (traction), are easy to charge and are a safe technology. There are drop-in lithium replacements but I see no need to go there at this stage.

Power from the batteries goes through a simple power board (a set of connector blocks and an on-off switch) and feeds the motors via the Motor Driver Board. It also powers the 3v/5v Power distribution board.

Power Distribution Board

Moana had plentiful 5v and 3.3v power distribution, including a USB socket. This worked well and kupe will use a similar mechanism. I pulled the buck converters from moana and reused them on a veroboard power distribution board. There is provision for ten 5v taps and ten 3.3v taps. I left room to add a couple of USB sockets, but have not added them as yet.

Powering the Raspberry Pi

The Raspberry Pi 5 I will add for optical processing needs power from a USB-C connector. I have a USB-A socket on Moana which I could repurpose (and connect via a USB-A to USB-C cable). I'm near the limit of what a USB-A can source with a Pi5, and if it proves troublecome, I will replace it for a USB-C daughter-board.

The usb daughter board was mounted on the extrusion above the power distribution board.

November 2025