SCPI Battery Charger - Raspberry Pi + OWON SPE Series

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Professional intelligent battery charger controller for OWON SPE series programmable power supplies running on Raspberry Pi.

Supported models: SPE3102, SPE3103, SPE6103, SPE6205 (and likely other SCPI-compatible PSUs)

Headless operation - fully controlled via MQTT and monitored remotely.

Features

Core Functionality

• OWON SPE Series Support - Full SCPI control (SPE3102/3103/6103/6205)
• Multiple Charging Modes - IUoU (3-stage), CV, Pulse, Trickle
• MQTT Integration - Complete monitoring and control
• Energy Accounting - Ah/Wh delivered and stored (Coulomb counting)
• Safety Monitoring - Multi-layer protection with automatic shutdown
• Data Logging - CSV logs with complete charging history

Advanced Features

• 26 Battery Profiles - Pre-configured for 2V/6V/12V/24V batteries (sealed & flooded)
• Battery Profile Switching - Change battery via MQTT without config edits
• Charge Scheduling - Schedule charging with start time and duration limits
• Battery History Tracking - Track charge cycles, capacity, and health over time
• Error Recovery - Auto-reconnect PSU and MQTT on connection failures
• Multi-Voltage Support - 0.01V to 60V (2V cells to 48V battery packs)
• Voltage Plateau Detection - Auto-stop for high-voltage flooded battery charging
• Power Monitoring - Real-time V/A/W measurements
• Temperature Sensor - Optional DS18B20 support for battery temperature
• Charging Efficiency Tracking - Accounts for 17% losses (heat/gas)
• Improved Progress Calculation - Smoother 0→70%→95%→100% progression
• Systemd Service - Auto-start, watchdog, automatic restart

Integration

• Home Assistant - Full integration with sensors and switches
• Remote Control - MQTT control from any client
• Web Dashboards - Compatible with Node-RED, Grafana, etc.
• SSH Access - Full Linux debugging and monitoring

CRITICAL: Battery Type Configuration

Modern batteries need DIFFERENT voltages than old batteries!

This project includes TWO configurations:

1. Lead-Calcium (Ca/Ca) - Modern batteries (2010+)

   • Uses 15.2V for charging
   • Default configuration
   • Most automotive batteries since 2010

2. Lead-Antimony (Sb) - Legacy batteries (pre-2010)

   • Uses 14.4V for charging
   • Separate configuration file
   • Older serviceable batteries

How to Check Your Battery

Quick check: When was your battery manufactured?

• 2010 or later → Use default config (lead-calcium)
• Before 2010 → Use charging_config_lead_antimony.yaml

Label check: Look for these markings:

• "Calcium", "Ca/Ca", "Maintenance Free" → Lead-calcium (15.2V)
• "Sb", "Antimony", removable caps → Lead-antimony (14.4V)

Full guide: See docs/BATTERY_TYPES.md for detailed identification

Why This Matters

Using wrong voltages:

• 14.4V on lead-calcium → Battery never fully charges → premature failure
• 15.2V on lead-antimony → Excessive gassing → water loss

Most "dead" batteries just need the correct charging voltage!

Configuration Files

# Modern lead-calcium battery (DEFAULT)
config/charging_config.yaml                    # 15.2V charging

# Legacy lead-antimony battery
config/charging_config_lead_antimony.yaml      # 14.4V charging

# To use legacy config:
python3 src/charger_main.py --config config/charging_config_lead_antimony.yaml

Technical References:

• German Battery Technical Wiki - Complete technical specifications
• Microcharge Forum: High-Voltage Charging - Expert charging methods
• OWON SPE/SP/SPS Programming Manual - Official SCPI command reference

These resources explain:

• Lead-calcium vs lead-antimony chemistry differences
• Correct charging voltages (Ladeschlussspannung: 17-17.5V for flooded)
• Traditional constant current method (150 years proven)
• State-of-charge voltage tables
• 12.5V critical threshold (80% SOC - must recharge immediately)
• Charging efficiency and losses

---

Hardware Setup

OWON SPE Series USB → Raspberry Pi USB Port (/dev/ttyUSB0)
                        ↓
                   Ethernet/WiFi
                        ↓
                    MQTT Broker
                        ↓
              Home Assistant / Dashboard

Choosing the Right PSU

Model	Voltage	Current	Power	Best For
SPE3102	30V	10A	200W	Batteries up to 70-80Ah (12V only)
SPE3103	30V	10A	300W	Batteries up to 70-80Ah (12V only)
SPE6103	60V	10A	300W	Batteries up to 70-80Ah (12V, 24V, 48V)
SPE6205	60V	20A	500W	Batteries up to 200Ah+ (12V, 24V, 48V)

Configuration templates are provided in config/psu_templates/ for each model.

See config/psu_templates/README.md for detailed PSU selection guide.

Quick Start

New to Raspberry Pi or Linux? → See Complete Installation Guide for step-by-step instructions!

Experienced users:

# 1. Install dependencies
sudo apt update
sudo apt install python3 python3-serial python3-paho-mqtt python3-yaml git mosquitto mosquitto-clients

# 2. Clone project
cd ~
git clone https://github.com/packerlschupfer/scpi-battery-charger.git battery-charger
cd battery-charger

# 3. Add user to dialout group (for USB access)
sudo usermod -a -G dialout $USER
# Log out and back in for this to take effect

# 4. Choose PSU template and configure for your battery
cp config/psu_templates/SPE6205_config.yaml config/charging_config.yaml
nano config/charging_config.yaml  # Edit battery capacity and current

# 5. Test manually first
python3 src/charger_main.py --auto-start

# 6. Install as systemd service (after testing!)
sudo cp battery-charger.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable battery-charger
sudo systemctl start battery-charger

Configuration

Edit config/charging_config.yaml:

# Power Supply
power_supply:
  model: "OWON SPE6205"
  port: "/dev/ttyUSB0"
  baudrate: 115200
  max_voltage: 60.0  # SPE6205: 60V max (0.01-60V range)
  max_current: 20.0  # SPE6205: 20A max (0.001-20A range)

# Battery
battery:
  type: "lead_calcium_flooded"  # Modern battery (2010+)
  nominal_voltage: 12.0
  capacity: 95.0  # Ah

# Charging Mode - Lead-Calcium Configuration
charging:
  default_mode: "IUoU"
  IUoU:
    bulk_current: 9.5         # 9.5A = C/10 rate for 95Ah
    absorption_voltage: 15.2  # Lead-calcium needs 15-15.4V!
    float_voltage: 13.8
    absorption_current_threshold: 1.0
    enable_float: true

# Safety Limits
safety:
  absolute_max_voltage: 16.5  # Safe for lead-calcium
  absolute_max_current: 20.0  # Hardware limit
  max_charging_duration: 43200  # 12 hours

# MQTT
mqtt:
  enabled: true
  broker: "localhost"
  port: 1883
  base_topic: "battery-charger"
  update_interval: 5.0  # seconds

MQTT Topics

Status (Published every 5 seconds)

battery-charger/status/online         # "true" / "false"
battery-charger/status/voltage        # 13.45 (V)
battery-charger/status/current        # 4.23 (A)
battery-charger/status/power          # 56.79 (W)
battery-charger/status/mode           # "IUoU"
battery-charger/status/state          # "charging" / "idle" / "completed"
battery-charger/status/stage          # "bulk" / "absorption" / "float" (IUoU mode)
battery-charger/status/elapsed        # 3600 (seconds)
battery-charger/status/progress       # 75 (%)

# Energy Accounting (Coulomb Counting)
battery-charger/status/ah_delivered   # 12.345 (Ah from PSU)
battery-charger/status/wh_delivered   # 175.23 (Wh energy consumed)
battery-charger/status/ah_stored      # 10.246 (Ah stored in battery, 83% efficiency)

# Complete JSON status
battery-charger/status/json           # Complete status as JSON

Commands (Subscribed)

battery-charger/cmd/start             # Payload: "" (start charging)
battery-charger/cmd/stop              # Payload: "" (stop charging)
battery-charger/cmd/mode              # Payload: "IUoU" / "CV" / "Pulse" / "Trickle"
battery-charger/cmd/current           # Payload: "5.0" (set current in A)
battery-charger/cmd/profile           # Payload: "12v_sealed_20ah" (switch battery profile)

# Charge Scheduling
battery-charger/cmd/schedule          # Payload: JSON {"start_time": "14:30", "duration": "2h", "profile": "lucas_44ah"}
battery-charger/cmd/schedule/cancel   # Payload: "" (cancel scheduled charge)

Battery Profile Examples:

• 12v_sealed_20ah - 12V 20Ah sealed/AGM battery
• 12v_flooded_75ah - 12V 75Ah flooded/wet battery
• 6v_flooded_200ah - 6V 200Ah golf cart battery
• 2v_sealed_100ah - 2V 100Ah industrial cell
• 24v_battery - 24V battery pack
• lucas_44ah - Lucas Premium LP063 44Ah (specific battery)

26 profiles available - See config/ directory or NEW_FEATURES.md

Home Assistant Integration

Add to configuration.yaml:

mqtt:
  sensor:
    - name: "Battery Voltage"
      state_topic: "battery-charger/status/voltage"
      unit_of_measurement: "V"
      device_class: voltage

    - name: "Battery Current"
      state_topic: "battery-charger/status/current"
      unit_of_measurement: "A"
      device_class: current

    - name: "Charging State"
      state_topic: "battery-charger/status/state"

    - name: "Charging Progress"
      state_topic: "battery-charger/status/progress"
      unit_of_measurement: "%"

  switch:
    - name: "Battery Charger"
      command_topic: "battery-charger/cmd/start"
      state_topic: "battery-charger/status/state"
      payload_on: ""
      payload_off: ""
      state_on: "charging"
      state_off: "idle"

Monitoring

Via MQTT Command Line

# Subscribe to all topics
mosquitto_sub -h localhost -t "battery-charger/#" -v

# Start charging
mosquitto_pub -h localhost -t "battery-charger/cmd/start" -m ""

# Stop charging
mosquitto_pub -h localhost -t "battery-charger/cmd/stop" -m ""

# Change mode
mosquitto_pub -h localhost -t "battery-charger/cmd/mode" -m "CV"

Via Logs

# Real-time logs
sudo journalctl -u battery-charger -f

# CSV data logs
tail -f ~/battery-charger/logs/charge_*.csv

Safety Features

Multi-Layer Protection

• Voltage Limits - Absolute max (18V), operational max (17.2V), warning (12.5V)
• Current Limits - Hardware enforced (20A max from SPE6205)
• Power Monitoring - Real-time V×A calculation
• Timeout Protection - Configurable max charging duration (default 12 hours)
• Temperature Monitoring - Optional DS18B20 sensor with high/low limits
• Voltage Plateau Detection - Auto-stop for flooded batteries above 16V
• 12.5V Warning Threshold - Critical SOC alert (80% - recharge immediately)

Reliability Features

• Automatic Shutdown - On safety violations, completion, or errors
• Systemd Watchdog - Auto-restart on crash
• MQTT Status - Real-time health monitoring
• Last Will Testament - Offline detection
• Complete Logging - All sessions logged to CSV with full history
• Energy Accounting - Track Ah/Wh delivered and stored

Charging Modes

IUoU (3-Stage) - Recommended for Most Cases

• Bulk: Constant current (C/10) until absorption voltage
• Absorption: Hold absorption voltage until current tapers
• Float: Maintain 13.5V (reduced from 13.8V to prevent grid corrosion)
• Automatic transitions between stages

CC (Constant Current) - Traditional 150-Year Method

• Pure constant current charging (C/10 rate)
• Best for open flooded batteries
• Uses voltage plateau detection for auto-stop
• Battery naturally reaches 17-17.5V when full

Conditioning (Tom's Method) - Advanced Maintenance

• Extended high-voltage (15.4-15.6V) for 24-48 hours
• For batteries that won't hold charge properly
• Improves resting voltage and charge retention
• Includes electrolysis detection
• Better than continuous float for storage batteries

CV (Constant Voltage)

• Hold target voltage, current tapers naturally
• Good for maintenance charging

Pulse

• Desulfation mode for neglected batteries
• Voltage pulses with rest periods
• For recovery of sulfated batteries

Trickle

• Low current maintenance
• Now uses 13.5V (reduced from 13.8V)
• For long-term storage

Troubleshooting

Service won't start

# Check status
sudo systemctl status battery-charger

# Check logs
sudo journalctl -u battery-charger -n 50

# Run manually to see errors
cd ~/battery-charger
python3 src/charger_main.py

OWON not found

# Check USB device
ls -l /dev/ttyUSB0

# Check permissions
sudo usermod -a -G dialout pi
# Log out and back in

# Test SCPI
python3 /tmp/test_owon.py

MQTT not working

# Check mosquitto running
sudo systemctl status mosquitto

# Test manually
mosquitto_pub -h localhost -t "test" -m "hello"
mosquitto_sub -h localhost -t "test"

File Structure

scpi-battery-charger/
├── README.md
├── battery-charger.service   # Systemd service file
├── requirements.txt           # Python dependencies
│
├── src/
│   ├── charger_main.py       # Main entry point
│   ├── owon_psu.py           # OWON SCPI driver
│   ├── charging_modes.py     # Charging algorithms
│   ├── safety_monitor.py     # Safety checks
│   └── mqtt_client.py        # MQTT integration
│
├── config/
│   └── charging_config.yaml  # Main configuration
│
├── logs/                     # Data logs (auto-created)
│   └── charge_*.csv
│
└── docs/
    ├── CHARGING_MODES.md     # Mode details
    └── MQTT_API.md           # MQTT topic reference

Documentation

Getting Started

• Installation Guide - Complete beginner-friendly setup guide
• PSU Selection Guide - Choose the right OWON model
• Battery Types Guide - Lead-calcium vs lead-antimony
• Systemd Service Setup - Auto-start configuration

New Features (2025)

• NEW_FEATURES.md - Battery profiles, scheduling, history tracking, error recovery
• 26 Battery Profiles - config/charging_config_*.yaml files for 2V-24V batteries
  • 12V Sealed (AGM/Gel): 7Ah, 12Ah, 20Ah, 35Ah, 75Ah, 100Ah
  • 12V Flooded: 45Ah, 60Ah, 75Ah, 100Ah, 200Ah
  • 6V Golf Cart: 200Ah, 250Ah
  • 2V Industrial: 100Ah, 200Ah, 600Ah
  • 24V Battery Packs, plus specific batteries (Lucas, Banner, 4MAX)

Support & Community

• GitHub Issues: https://github.com/packerlschupfer/scpi-battery-charger/issues
• Configuration Help: See config/psu_templates/README.md
• Logs: ~/battery-charger/logs/ and journalctl -u battery-charger -f
• MQTT Testing: mosquitto_sub -h localhost -t 'battery-charger/#' -v

License

MIT License - See LICENSE file for details