What I hate is even when my batteries were up to snuff my water pump always seems real slow just before it shuts off and even makes you think your batteries are near dead.

I remember my old trailer doing the same thing but never found a fix for it except buying an expensive pump for it that changed speed along with the demand, but it only lasted a year when I had some flashing lights in the trailer and found a circuit breaker failing on the frame rail and after fixing it found that the bad voltage from the connection that it let all the smoke out of my expensive water pump.

I ran across an interesting idea at Amazon and I bought one of these.

My water pump is in a deep dark hole so I tapped into the wiring at the power center for it and mounted it right on the cover where it has air flow from the fan for the power converter.

Adjusting the unit I noticed that it had very precise control over the voltage by turning the small screw. I tested it with the batteries at full charge and after a long day of use with the solar panels off and the voltage at 12.3v. Well the conclusion is that the unit still provided the 14.3 to the water pump and it really performs good.

One more note: I like running a surge tank so that when I just fill one small item with water that it doesn't cycle the pump.

 

Neat idea. I can think of a couple of things for that in and out of the RV

 

Agreed. Very cool idea...