I have a regular sump. My regular sump pump is a 1/2 HP Zoeller M137
pump. It works very well and I am not complaining. I bought it, by the
way, based on Edwin's advice on this newsgroup.

My question is about a good selection for a backup. I have a nice
finished basement. I want to have a well thought out backup system.

1) I would like it to operate from both a battery as well as 120v,
meaning that if it runs off a battery, and 120v is available, the
charger should keep up with keeping battery charged as the pump is
running. In other words, it should be able to operate indefinitely if
120v is available. I also want it to be able to use extra batteries (I
have three marine batteries that I may as well hook up to this
system).

2) I want it to be very well made, not like cheap "homeowner backup"
stuff that is never seriously meant to be used

3) I would like it to have some diagnostic features like warning me
about battery condition or about the fact that it is running.

I am aware of brands such as "basement watchdog" etc, but what I want
to know which one is a very honestly made system that has a lot of
reliability features.

i