Sump pump backup

For those who have a sump pump, Ryan Homes strongly suggests you have a backup battery installed. Why?  Well, if the power goes out, the sump pump won't work and your basement might take on water. Or something like that. 

I heard that the sump pump failed to work in my neighbors house and his basement filled up with water so I decided to bite the bullet and have it done.  

Here is the picture of the completed work ... I have no clue how this works, I just hope it does.