Originally Posted By: burgermeister
If you are dead set on using the AC pump, i.e., better more powerful, longer lasting, whatever, then the relay is a good idea.
You would need a double pole double throw(dpdt) relay with 115vac coil. You would break one side of the ac line to the ac pump(preferably the neutral). Connect the pump side of broken line to the common of one set of relay contacts; the 'power' side of line to the nc(normally closed) or energized side of the relay. you also connect the coil to the ac.
Use the 2nd set of relay contacts in a similar fashion with one side of the DC line, but place the battery side of the line to the N.O. or normally open(deenergized ) side of the set of contacts.
If the DC pump is good for continued usage, use the charger and battery. I would suggest to remove the charger and let the pump run on battery only each month for a while to keep the battery in good condition.


Thanks Burger. I'll relay that to my dad who was an I & R telephone guy for 21 years after serving in the military for 20. I have no clue what you said but I'm sure my dad will.

Last edited by Cecil Baird1; 11/07/09 06:26 PM.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.