Problem:
I have add different devices on my bike. The problem is either they are directly connected to the battery and they draw a leakage current or after the main switch and are not available when I switch off my bike.

Examples:

You need to charge your phone during a break and your USB charging port is connected after the main switch. You need to turn on the main switch and your battery will be loaded for the lights and motor control electronic. Or you put it directly to the battery with a switch. I such case, if you once forget to switch off your circuit, you'll may be not able to start on the next day or a week later...

You have a navigation device and it ask to switch off at any small break as soon you switch off the main Key.

You have a 3DMS device to measure your performances. It is usually directly connected to the battery. If yout forget to switch it off and it will draw down your battery after a week or so.

Step 1: My Solution

I just connect all my device after a so called Delayed Switch Off Timer. The Idea is activate a relay on switch on and deactivate it after a certain time (30 minutes in my actual case). All my devices are connected after this switch device. Circuits:

The circuit is completely switched off when therelay is disconnected => 0 leak current

Step 2: Step 2 :The Technology

The brain is an arduino nano that could be supplied from 7 to 12 V. It will detect the main switch on position, switch on the relay, detect the main switch off position and start a timer to switch off the relay after 30 minutes. A current probe ensure to delay the switch off only when it is needed. (no charge = no delay)

As I have had 6 V relays, I decide to reduce and stabilize the battery voltage to 7V. This could be adapted to another value but it will be good to not put it directly on the battery that can go up to 14.5V

Step 3: Step 3 : Check the Current

The current is measured on the ground path and the timer switch off immediately when the current is lower than about 50 mA (no charge detected)

Step 4: Step 4 : Mount All in a Box

I have mount all in a small box using a three wires connector for as well at the input as for the output. So it will be possible to remove the timer device and connect the two cables directly in case of troubles.

I the add some small two wires connectors on the output to connect my electronic devices and a larger one for the USB Plug.