Hoping to convert a couple 12V DC sump pumps to run off 120V AC...Wondering if someone can give me some pointers?

I found a unit that I think will work - a Tripplite PR20 20 amp AC --> DC power supply, which plugs into regular AC and converts to 13.8 volt DC, but I'm hoping somebody can tell me A) If it will, in fact work B) what will happen if it doesn't C) Can I get away with a lower amp version of the Tripplite unit? Do I need a higher amp version? D) Whether or not the power supply will draw continuously from the outlet even when the sump pump isn't running, thereby jacking up my electric bill to the point the project isn't worthwhile.  The pumps are from two different brands of battery back up sump systems;  Basement Watchdog, and Ace in the Hole, but seem to be of the same power demand and hp.  I would only be hooking one of them up at any given time to the PR20.  I also have a 12v dc float switch on which I would install an interrupter plug  to make this work (until it wore out, at which point I'd switch to an AC float switch with interrupter and plug the Tripplite into that...).   I know I'm making more trouble for myself than it's probably worth, but these pumps are brand new, and I could save a couple hundred bucks if I can make them work...Any help or advice you could offer would be great.  The Tripplite unit specs are available at Tripplite.com; just do a "model search" under PR20, or PR...There are a whole line of different models w/varying amp ratings...

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iceng6 years ago
A) it will work.
B) if it does not, you may flood lower level and have to buy an AC sump pump sooner.
C) Occasionally Wall-mart will hold a Sale on automotive chargers under $20 for 30 amperes. Tripplite is a good company but overly expen$ive.
You probably don't know the current draw of your battery pumps but did you charge these pump batteries from a small wall plug ?
D) The 120VAC to 12VDC chargers also known as TR (Transformer Rectifier) units when left plugged in can waste 2% to 8% of full load.
E) The down side of the 12V pumps is that they are probably brush units and short lived when compared to a 120V AC motor pump usually as long lived as the bearings.
F) Your float switch concept is sound.
G) Harbor Freight has AC sump pumps for under $100.

I hope this helps,

I'm with you on the longevity thing - these baby 12V units are nothing like as effective as a mains one, but then again the OP might be off grid or something.

herbacious (author)  steveastrouk6 years ago
Thanks Steve! I told the wife I would proceed based what folks said on here, and I guess I'm getting my answer!
That does happen in my wild State of Nevada.

herbacious (author)  iceng6 years ago
Thanks for the info, you've helped me towards realizing it's probably not worth the time or money to do this (since the objective was to save a little money). All things being equal, I'm sure I will appreciate the extra confidence I will get from just using an AC pump! Thanks!
orksecurity6 years ago
Should work. Though you should be able to find power supplies that put out the 12V you officially want.

To find out how much amperage you need, you need to know the wattage of the motors. That's probably printed on the pumps. Watts divided by volts yields amps.

Power supplies are not perfectly efficient, so they do waste a bit of energy... but generally if you aren't drawing power from a transformer it's pretty close to being a pure inductor and thus draws very little power from the wall.
herbacious (author)  orksecurity6 years ago
Thanks, you guys have been of great help with this. I wish I'd happened upon this site a long time ago!
Your wife has a admirable husband.