I decided to make my own instead of bying one on ebay (from 50$ to 120$)
Its basically only capacitor, I decided to use 2 big capacitor instead of many small like the current voltage stabilizer on ebay. Also
the one you can buy on ebay are always working even if the car is not running. I added a relay connected to the headlight fusebox.
So the voltage stabilizer is only working when I am riding, this help to not draw any current from the battery while you are not using the car.
I use 2 big powerlytic 50v 120000 uF capacitor, one relay, one resistor, one led, one diode and one 15A fuse with some wire for this project.
Here some photo of the ugly beast!