Lv power sys

HomePowerBank

This project is a combined hardware-software effort around designing a control / management system for a home power bank. Unlike commercial USB power banks, this one is intended to serve as a sort of "generator substitute," having a stack of batteries large enough to supply an inverter during situations that otherwise lack power (general outage, off-grid living, etc).

Design Goals

Primary Goals

• Monitor a multi-cell battery stack
  • Measure cell voltage
  • Measure stack voltage
  • Measure stack current
  • Measure temperatures
  • Estimate cell state-of-charge
• Report monitored state to user
• Accept and react to user input for basic operations
• Protect pack against fault conditions
  • Overvoltage / Overcharge
  • Undervoltage / Undercharge
  • Overcurrent
  • Overtemperature
• Integrate control of external charger and inverter
  • Connect & disconnect battery stack bus and external devices
  • Produce on/off control output to charger
  • Take in fault input from charger
  • Produce on/off control output to inverter
  • Take in fault input from inverter

Secondary Goals

• Provide bidirectional USB-C charging port
  • Supply external loads with 5V 1.5A power
  • Trickle-charge bank from external supply
• Take control commands from external communication interface
• Implement advanced diagnostics
• Implement flexible / extensible stack architecture
  • Adapt to different cell and IC counts
  • Adapt to different cell chemistries

Tools

As much as possible, the tools used to produce the design should be freely available.

• Circuit schematic and layout creation will take place in KiCAD
• Block diagrams and similar drawing should use draw.io
• Circuit simulations should be conducted in a free SPICE tool, like ngspice or LTSpice
• Documentation should be created using the Markdown language / format

Philosophy

System Design

When in doubt, design should err on the side of over-engineering, especially for the prototype phase.

Project Code of Conduct

"Be excellent to each other" - Bill S. Preston, Esq.

Usability

The system in basic form should be fully usable from the standpoint of a non-engineer, but should also offer the capabilities for a knowledgeable person to modify / alter the system to their desires.