reply to dick white
Re: Sump pump w/ battery backup During Sandy in Annapolis my section of the neighborhood lost power for about 18 hours. Next-door neighbor has a 110v sump pump with a 12v battery backup. By nightfall Monday we had 4" of rain and their basement was flooding due to the battery powered pump being overwhelmed by the water volume, and the battery being depleted after a few hours of running.
I ran a long extension cord to their house to get their main pump running again.
Anyway, the moral of the story is that the type of pump backup you choose depends entirely on the site specifics--how much water could possibly flow into your basement, what would be destroyed if it were to flood, etc.
Another thing to consider is to have something like this on hand:
Moral of the story is that you should have a MAIN type of backup for everything (Generator) and focus your "maintenance" time on that generator.
When an event like Sandy occurs, you're sure it will work.
I can understand the battery as a "bonus" to use it while you have the generator turned off to save fuel.