Set up an emergency back-up battery system that is always charged - electricity.straw.backup PEP BB

This is a badge bit (BB) that is part of the PEP curriculum.  Completing this BB is part of getting the straw badge in Electricity.

In this Badge Bit, you will build an emergency back-up battery system that is always charged.  Don't you hate it when the power goes out and you need to charge batteries and run some lights?  Let's make a system to help out!

Here's a video of a guy making one for his aquarium:


To complete this BB, the minimum requirements are:
  - includes a 7 amp hour battery or larger
  - has a light to indicate it's fully charged
  - can stay plugged in forever so it's always charged
  - has output wiring that matches your needs (maybe an inverter for 110V use)
  - it does not need to be in a water proof case, use your own judgement based on your application

To show you've completed this Badge Bit, provide proof of the following as pics or video (less than two minutes):
  - the parts you're putting together
  - a short description of the build
  - the assembled back-up battery system
  - the system charged (light on)
  - the system powering a device