Most people who have a Speedster know that when you leave it standing for a while, the battery drains pretty quickly. I often forget to disconnect the battery. Or, when I do remember it usually turns out that I want to drive it shortly afterwards.

A while ago I ran into the Battery Brain, a device that monitors the battery and when it reaches a specific voltage (11.8V) it disconnects the battery. Intruiged, I decided to order one.

Before trying to fit it to the Speedster, I decided to test it, with the test setup below.

In the video below you can see the blue Watt meter box. That measures the supplied voltage to the Battery Brain. I turn it down to below 11.8V. Then the Battery Brain takes a while before it decides to shut off the supply to the voltmeter. Resetting the Battery Brain by pressing the button restores power.

Your browser does not support the video tag.\

To make sure the Battery Brain doesn't shut off the power while driving, it has an input signal which can be linked to a switch 12V source. I used the signal from the fusebox, from fuse 7. This seems to work well.

After moving parts around a while and trying different configurations I ended up with the configuration below.

During a testdrive I didn't run into any problems, everything seems to work well. Now I'll have to wait and see what happens when I leave the car for a couple of weeks :)