Help with service light when braking

Help! Muy twizy is having the service Light on and the Small Battery Simbol with the ! On but only when i brake. It runs fine, the regens works but when i press the brake the signals turn on. Any ideas?

Your 12V Accessory battery is undercharged. Charge it up off the car or change it. Soon you will not be able to start the Twizy or even charge the main battery.

At least it is a simple fix.

i was thinking that, and i charged it and only after 2 minutes, it showed that it was fully charged, so it is not that. the car seems to work just fine, i am hoping it has to do with just brake pads and they need to be changed, i have 24k km and really hope it does not have anything to do with actual battery. will take it to the dealer today