Never Get Stranded Again: Building the ThrillFishing Battery Monitor

Nothing ruins a perfect day of fishing or boating like a dead battery. That’s why I built the ThrillFishing Battery Monitor—a custom device designed to keep an eye on your marine batteries and send real-time updates and alerts to your phone or computer.

It monitors voltage (battery level), current (power flow), and temperature (to prevent overheating), and reports this data every two minutes over Wi-Fi to Home Assistant, an open-source smart home dashboard. With this system, you can easily monitor your battery’s health, prevent breakdowns, and enjoy more worry-free time on the water.

Here’s an overview of how I built it—and how you can too. If you’d like the full details (sensor specs, wiring diagrams, 3D printable case files, network setup, and application code), feel free to reach out via email at [email protected].

Why Build the ThrillFishing Battery Monitor?

Marine batteries endure a tough environment—constant cycling, salty air, and fluctuating temperatures. A basic multimeter doesn’t tell the whole story. That’s where this monitor comes in:

• Tracks voltage to show how charged your battery is.

• Measures current to detect abnormal draining or charging.

• Monitors temperature to prevent overheating that can reduce battery life.

• Sends real-time data to Home Assistant, where you can view it all in one clean dashboard.

This gives you the power to catch small issues before they turn into major problems—and keeps your vessel’s electrical system running smoothly.

What You’ll Need

Here’s a parts list to build your own ThrillFishing Battery Monitor:

• ESP32 Microcontroller – Wi-Fi-enabled brain of the system ($10–$15)

• INA226 Voltage/Current Sensor – Accurate voltage measurement for 12V or 24V systems

• HSTS016L Current Sensor – Measures power draw and charge

• DS18B20 Temperature Sensor – Waterproof sensor for battery heat monitoring

• 12V to 5V Buck Converter – Powers the ESP32 from your boat battery

• IP67 Waterproof Enclosure – Keeps everything safe from the marine environment (can be 3D printed)

• Wi-Fi Access Point – Use your boat’s Wi-Fi or a portable hotspot

• Extras: Breadboard, jumper wires, soldering supplies, marine-grade wire and fuses

💡 Total Cost: Around $50–$70 depending on where you source parts (Amazon, Adafruit, eBay, etc.)

Real-Time Monitoring in Action

After weeks of testing on my fishing boat, the monitor has proven to be a game-changer. I now get proactive alerts on my phone or smartwatch when battery voltage drops too low—so I can start the engine and recharge before there’s a problem.

The Home Assistant dashboard shows live and historical data, helping me stay ahead of maintenance and better plan battery replacements.

A recent upgrade allows the ESP32 to automatically switch between my marina’s Wi-Fi when docked and my phone’s hotspot when out on the water, keeping monitoring seamless wherever I go.

Battery Data: Sample Dashboard

Battery Data: Graphical View

Battery Data: Real-time Alerts

This critical alert can be send to phone, watch, email or text.   Notifications can identify problems like low voltage, batteries not charging, short circuits and high temperatures.

Summary: Empowering DIY for Safer Boating

This isn’t just a DIY gadget—it’s a smart upgrade that brings peace of mind, convenience, and safety to your boating experience.  This is an expandable platform for monitoring your boat.  I plan to add other sensors to track boat bilge pumps to further enhance boat safety and reliability.

Communities like Reddit’s r/homeassistant are full of helpful users who’ve added features like low-voltage push alerts, solar integration.

Tips for Your Build

• 🔧 Calibrate Sensors – Use a multimeter to compare and fine-tune readings.

• 📶 Boost Wi-Fi Range – Consider a high-gain antenna if coverage is weak offshore.

• ⚠️ Prioritize Safety – Use marine-grade wire, waterproof fuses, and solid connections for reliability.

Get Started Today!

The ThrillFishing Battery Monitor is more than just a project—it’s your gateway to smarter, safer boating. Gather your components, fire up your computer, and dive into the world of DIY marine tech.

Happy fishing—and may your batteries always stay charged!

Tight lines …  Captain P.