Keith,

I've gone through two battery-back up systems using battery-powered DC
motors in this house since 1990. I've really never been happy with
their performance, and the deep-cycle marine batteries never seem to
last as long as they should.

Although I know the initial inductive kick of the typical AC sump pump
pulls quite a bit of current, it seems to me the best alternative would
be analagous to a computer UPS. Simply plug the normal sump pump into
the UPS-like device, and once there's a AC power outage, the device's
inverter takes over and feeds the pump with 115VAC.

Personally, I've always thought such a device would be a big seller
throughout the country, but I've never seen such a product. Most
likely, it's due to the overall cost because of the initial turn-on
current requirement, as well as the continuous current use, of most sump
pumps.

Nevertheless, I still think it's a viable idea, and if someone could
come up with an effective design and manufacture it in China, perhaps it
could be brought to market for a reasonable price.