Buddy of mine is looking for a unit that will give him some back-up
for his sump pump. What he wants is a device that:

Plugs into an outlet
The pump plugs into the device
The device trickle charges a car battery
If AC power fails the battery provides AC through the device

I've done some googling but can only find complete systems with
battery included or stand-alone inverters. He already has the battery
and pump just needs the 'device'. Anyone know where to get such a
gizmo?

If he uses a DC pump, like a marine bildge pump, then all he needs to
do is attach that to the battery with the float switch in series with
the pump. The pump runs off the battery. The charge keeps the battery
charged. Like a "UPS." In fact, a UPS might do the trick if it will
handle a load like a small pump.

On Feb 6, 9:23?am, "professorpaul" wrote:
If he uses a DC pump, like a marine bildge pump, then all he needs to
do is attach that to the battery with the float switch in series with
the pump. The pump runs off the battery. The charge keeps the battery
charged. Like a "UPS." In fact, a UPS might do the trick if it will
handle a load like a small pump.

you use a small cheap charger on the battery and will need to replace
it every few years. trickle charger

you put the float switch above the level of the regular pumps switch
so it kicks on in high demand or power failure. either way prevents
floods.

use a backup DC pump and ideally a seperate drain line in case the
primary one fails for some reason.!!!!

Using a nverter or UPS isnt a good idea, the conversion loss from 12v
to 120 will waste a LOT of the batteries power. UPSs espically are
built for clean computer grade power whereas sump pump duty needs
brute force.

I am amazed how mnany neighbors have pumps that COULD drain or
overflow drain by gravity. the pump owner should look at this gravity
tends to be reliable does require digging

wrote in message
oups.com...
On Feb 6, 9:23?am, "professorpaul" wrote:
If he uses a DC pump, like a marine bildge pump, then all he needs to
do is attach that to the battery with the float switch in series with
the pump. The pump runs off the battery. The charge keeps the battery
charged. Like a "UPS." In fact, a UPS might do the trick if it will
handle a load like a small pump.

you use a small cheap charger on the battery and will need to replace
it every few years. trickle charger

you put the float switch above the level of the regular pumps switch
so it kicks on in high demand or power failure. either way prevents
floods.

use a backup DC pump and ideally a seperate drain line in case the
primary one fails for some reason.!!!!

Using a nverter or UPS isnt a good idea, the conversion loss from 12v
to 120 will waste a LOT of the batteries power. UPSs espically are
built for clean computer grade power whereas sump pump duty needs
brute force.

Funny how many people assume that. UPSs produce square waves because
computer power supplies don't much care what they get. Pumps on the other
hand really need sine waves, which are much more expensive.
An adequate inverter for a pump would be cost prohibitive.