Smart Motorcycle Power Manager: Build a Delayed Switch Off Timer for Your Devices

Problem:

I have added various devices to my motorcycle. The issue is that if they are directly connected to the battery, they draw a leakage current. If connected after the main switch, they become unavailable when the motorcycle is switched off.

Examples:

1. Charging Devices During Breaks:

• You need to charge your phone during a break, but your USB charging port is connected after the main switch. You have to turn on the main switch, which draws power for the lights and motor control electronics, draining the battery.
• Alternatively, you could connect it directly to the battery with a switch. However, if you forget to turn off the switch, your battery might be dead the next day or a week later.

1. Navigation Device:

• Your navigation device asks to shut down during any short break as soon as you switch off the main key.

1. 3DMS Device:

• A 3DMS device measures your performance and is usually connected directly to the battery. If you forget to switch it off, it will drain your battery after a week or so.

This creates a dilemma between having devices available without draining the battery or risking battery depletion due to leakage current. My solution addresses these issues by automatically managing power to these devices.

I have built a small device to manage the power supply to all additional electric devices on my motorcycle. This device automatically switches off connected devices after 30 minutes or when the current drops below a certain threshold. Here’s how it works and how you can build it yourself.

How It Works

The key idea is to use a Delayed Switch Off Timer. This timer activates a relay when the motorcycle is turned on and deactivates it after a set period (30 minutes in my case). All my devices are connected through this switch.

Circuit Features:

• The circuit is completely off when the relay is disconnected, ensuring 0 leakage current.

The brain of this device is an Arduino Nano, which can be powered from 7 to 12 V. It detects when the motorcycle is turned on, activates the relay, and starts a timer when the motorcycle is turned off to deactivate the relay after 30 minutes. A current probe ensures the relay only stays on when needed (no load = no delay).

Power Supply

Since I had 6 V relays, I decided to reduce and stabilize the battery voltage to 7V. This can be adjusted for different components, but it’s crucial not to connect it directly to the battery, which can reach up to 14.5V.

The current is measured on the ground path, and the timer switches off immediately when the current drops below approximately 50 mA, indicating no load.

I mounted everything in a small box using three-wire connectors for both input and output. This setup allows for easy removal of the timer device if needed, enabling direct connection of the cables.

Additionally, I added small two-wire connectors on the output to connect my electronic devices and a larger one for the USB plug. The box features two small waterproof three-pin cables.

All connectors are oriented the same way: pins from the device towards the battery and holes from the battery towards the devices.

I chose to use adapter cables instead of plugging everything directly into the box for two main reasons:

1. It’s more flexible to mount.
2. I can remove the box and connect the input and output cables directly, ensuring all devices are still connected to the battery.