# [Need Help] -> Bibycle Brake System using LED strip

Joined Aug 23, 2018
3
Hello everyone!

I'm new to this forum and also new to electricity, beside knowing some basics, like the Ohms law. As I've bought myself a new bike, I want to pimp it up with self-made brake lights, using a LED strip. Although it may seem quite simple, I still want my idea and calculations to be prooven by experts. Here is what I have imagined to do:

1) The circuit would be supplied by a Duracell Alkaline MN1604 9V battery, connecting it to a battery cap, to easily connect the wires

2) I would use 5cm of a LED strip with 14,4W/m (60x0,08W) and a voltage of 12V. There would be 3 LEDs on 5cm, so they would need 0,72W of power, if considering that 1m needs 14,4W. Based on the equation P=V*I, where P=0,72W and V=12V, there would flow a current of 0,06A through the strip. I've heard that a LED strip has a biult-in circuit, which means I need to connect the strip with wires only from one side?

3) The main problem for me are the resistors. I've read that most LED strips have biuld-in resistors, but I'm not sure if they can limit every current. I want to calculate the needed resistance for my circuit with the equation R=V/I, but I don't know what voltage should I put in, because the voltage of the LEDs is bigger than the voltage of the power supply. Should I calculate with the difference of the voltages (3V), although the answer would be negative? Will it still cause, when not using resistors, the LEDs to burn out?

4) I've got problems removing the silicone cover from the strip. Some people advice to peel it off gently with a knife, which I've tried and removed a bit of the white covering, but only with scratching, until I saw some copper beneath and stopped, because I thought I could damage the poles. What do you suggest me to do? I've put a screenshot of the current state of the strip.

5) The circuit would be connected together via 2 aluminium squares (1cm^2), each one would be connected to a wire. The squares would stick together, when the brake lever would cause the V-brake Chrome to compress. Would that be an efficient connection?

That's all for now. Every answer and critique is more than welcome!

Warm Greetings,

Joined Aug 23, 2018
3
Edit: image link won't work, can't edit original post, because of suspected spam.

#### oz93666

Joined Sep 7, 2010
737
Your link doesn't work for me ,but that doesn't matter ....You say these are strips designed for 12V ... these are very common and are meant to just be connected to 12V ... that's it , they have limiting resistors built in .... You may be able to get some light by connecting them to your 9V battery , they will draw a fraction of the power ,so if they're bright enough for you the battery should last a long time . The wires need to be connected to the battery the correct way ,if no light try the other way , you won't damage them by wrong connection , they just won't work ...