Tuesday, January 11, 2011

Pro-Fill Battery Watering System

Maintaining the proper water level in your batteries is crucial for their long-term health and ability to provide maximum power output. It's possible to do this fairly cheaply, using a turkey baster and a small mirror. But it is hard to get the level exactly right, especially for the cells near the back of the batteries. The battery tray only pulls out so far.

Many RV'ers have opted to install a Pro-Fill On-Board Battery Watering System, which makes the job much easier. To quote from the manufacturer's web site:
  • Fill up to six batteries in seconds from a single fill point
  • Fits all standard 6V lead acid batteries
  • Eliminates need to remove vent covers to fill
  • Automatically sends water to low cells only
  • Installs in minutes, no tools required
  • Safer and more accurate than conventional filling
  • Improves battery life and performance
  • Hard to reach batteries are as simple to fill as batteries on a workbench
  • Several batteries can be connected and filled at the same time
  • Automatic shut-off prevents over or under watering
  • Simple hand pump operation
  • Use with any distilled water container
  • Quick disconnect feature allows supply to be attached in a snap
  • No need to remove vent covers

The Pro-fill system consists of a set of battery caps connected by a series of tubing and a hand-squeeze bulb pump.

To install, first remove the stock battery caps from each cell. Insert the new set of caps with their tubing. Install so that the quick-connect fitting is near the front of the batteries. That's it.

To use, insert the intake-end of the tubing from the hand pump and put it into the container of distilled water. While holding the other end of the tube up, SLOWLY squeeze the pump until the water has risen to the upper end of the tubing. Fasten the tubing to the quick-connect fitting on top of the batteries. Now squeeze the pump to force the water into the cells. Keep pumping until the bulb becomes hard to squeeze, the indication that the cells are properly filled. Generally it shouldn't take more than 1-3 squeezes under normal conditions.

When finished, disconnect the pump tube and drain the water from it. You can either drain the water back into the container, or, if you're concerned about contaminating the water in the container, merely discard the water from the tube.


Occasionally, especially with an earlier version of the squeeze bulb pump, the valve ball will become lodged in the valve and will not allow water through the bulb. This happened to me a few years ago. A call to the company resulted in their sending me a new pump, free of charge, which has worked fine since then. I found Flow-Rite to be very customer-oriented.
Web Site: www.flow-rite.com

Here's another solution: On-line sources provided only a full pump system (bulb/check vales/tubing) replacement for $$. Email requests to Flowrite for guidance/assistance went un-answered. A trip to Walmart's "marine" section provided the solution for $6 and change.

Attwood Primer Bulb (with installed check valves)
Universal - 3/8ths
PN 9362LP7
UPC 0 2269793628 8

Remove tubing from both ends of Pro-Fill bulb and place on the Attwood bulb paying attention to the water flow direction as marked on the new bulb.

The Attwood bulb appears to be of much stronger construction than the Pro-Fill.

Another problem may be the check-valve at the coupler end, which won't allow water to pass through to the batteries. A very simple fix is to wiggle the plunger in the middle of the coupler; this might be enough to free it up.

Contributors: WxToad, George, Mike Lewis

Revised 25 Jun 2013

Return to FAQ Index