Stop guessing, stop overfilling, and stop removing vent caps one at a time. The Flow-Rite BG-U24V-4G-WS Pro-Fill system lets you water all four batteries in a 24V, series-wired 6V bank in a single fill -- through one port -- with automatic shut-off valves that stop water flow the instant each cell hits the correct level.
Proper battery maintenance is the single biggest factor in deep-cycle battery life, and getting the electrolyte level right in every cell is where most RV owners fall short. Underfilling dries out plates; overfilling washes away electrolyte and corrodes terminals. The Flow-Rite Pro-Fill system removes the guesswork entirely.
This kit is configured for a 24-volt bank made up of four 6-volt batteries wired in series -- a common setup in RVs, coaches, and towables running dual 6V golf-cart-style deep-cycle batteries per pair. The non-standard spacing designation means the tubing and valve positions are sized for banks where battery-to-battery distances do not match standard close-coupled configurations, accommodating battery trays with extra gaps or non-uniform layouts.
Each automatic shut-off valve threads directly into the existing vent cap opening on each battery cell. When water reaches the correct electrolyte level, a float mechanism inside the valve seals off flow -- instantly and independently for each cell. No timers, no guessing, no spills.
Float-actuated valves stop flow the moment each cell reaches the correct fill level -- no overfilling possible.
One hand pump connection waters all four batteries simultaneously through a closed tubing loop.
Tubing lengths accommodate battery banks with extra gap between units -- no trimming needed for standard close-coupled layouts.
The included hand pump pressurizes water from a jug or hose through the fill port -- no power source needed.
This is a complete, ready-to-install kit. Flow-Rite ships everything needed to convert four 6V batteries to single-point watering:
Some Pro-Fill kits use a central manifold to distribute water across all cells. This non-standard-spacing version routes tubing directly between adjacent cells without a manifold, keeping the plumbing low-profile and flexible in battery trays where a rigid manifold block would not fit. Filling pressure is supplied entirely by the hand pump pushing water through the interconnected valve chain.
Installation is straightforward. Remove each existing vent cap and thread in the Pro-Fill automatic fill valve. Connect the valves across all cells with the supplied tubing. Attach the single fill point coupler to your last valve. When it is time to water, press the hand pump hose onto the fill point and pump until water flows back out of the indicator -- the signal that all cells are full. Disconnect and store the pump. Total service time for a 4-battery bank is typically under two minutes.
The float valves are rated for use with distilled or deionized water as recommended for flooded lead-acid deep-cycle batteries. Using tap water with high mineral content will shorten valve service life.
The Pro-Fill system is designed for flooded (wet cell) lead-acid batteries -- the type that require periodic water addition. It is NOT compatible with AGM, gel, or sealed VRLA batteries, which are maintenance-free and have no fill ports.
This kit is a natural fit for RVs running a 24V house bank built from four 6V deep-cycle batteries, as well as motorhomes, fifth-wheels, and toy haulers where the battery compartment layout creates uneven spacing between units. It is also used in electric vehicles, floor scrubbers, and lift equipment using 24V, 4x6V banks -- but the valve size and thread spec are chosen to match standard L-style and similar 6V deep-cycle battery vent openings common across RV and industrial applications.
This kit is specifically configured for battery banks where the batteries are NOT in tight side-by-side contact. If your four 6V batteries sit in close-coupled pairs with minimal gap, you may need the standard-spacing version instead. Measure battery-to-battery center distances before ordering to confirm tubing lengths will reach without excess slack or tension.