Stop pulling vent caps one by one. The BG-U72V-7J lets you water every cell in your Trojan battery bank through a single fill point -- automatic shut-off valves stop flow the instant each cell reaches the correct level, eliminating overfill damage and dry-cell risk.
Battery maintenance is the most neglected -- and most damaging -- task in RV ownership. Deep-cycle flooded batteries lose water during every charge cycle, and underfilling accelerates sulfation while overfilling dilutes electrolyte and corrodes terminals. The Flow-Rite Pro-Fill system replaces your existing vent caps with precision automatic shut-off valves, interconnects them with flexible manifold tubing, and routes everything to a single external fill port.
Part number BG-U72V-7J is purpose-built for the common Trojan battery configurations found in RV house banks: a 24V bank of (12) 6V batteries, or a 12V/24V bank of (6) 12V batteries. The 127 flex manifolds provide the routing flexibility needed to bridge cells across multiple batteries regardless of their physical arrangement in the battery tray.
Valve seals automatically when the correct electrolyte level is reached -- no guessing, no overflow.
Pre-cut flexible manifold segments route between cells and across battery tops with minimal effort.
Connect a hose or hand pump to one port and water every cell simultaneously in seconds.
Valve bodies sized and threaded for Trojan T-series 6V and GEL/AGM-free 12V flooded battery fill ports.
This is a complete watering kit -- everything needed for installation is in the box:
Trojan and other deep-cycle flooded battery manufacturers recommend maintaining electrolyte 1/8 to 3/8 inch above the plates. Manual filling with a squeeze bottle or jug makes consistent levels across 24 or more cells nearly impossible. The Pro-Fill valve float mechanism shuts off flow at the same level every time, extending battery cycle life and reducing the frequency of equalization charges needed to correct cell imbalance caused by uneven water levels.
Each automatic valve screws directly into the cell opening, replacing the factory vent cap. Inside the valve, a float rises with the electrolyte level and seals the inlet when the correct level is reached -- similar in principle to a toilet fill valve. The flex manifold tubing connects each valve to its neighbors, creating a closed loop across all cells. When you connect your water source to the fill port and open flow, water distributes through the manifold and enters each cell simultaneously. Cells that are already full accept no water; low cells fill until the valve closes. The entire process for a 12-battery bank typically takes under two minutes.
The single fill port on this system accepts a standard Flow-Rite hand pump, gravity-feed bottle, or a powered battery watering pump (sold separately). Use distilled or deionized water only -- mineral-rich tap water deposits scale inside valve seats and shortens valve service life. The fill port is compatible with Flow-Rite quick-connect accessories.
The Pro-Fill system is designed exclusively for vented flooded lead-acid batteries that require periodic water addition. AGM (absorbed glass mat) and gel batteries are sealed and must never be opened or fitted with external watering valves. Verify your Trojan batteries are the flooded/wet-cell type before ordering -- Trojan T-105, T-125, T-145, T-1275, J185, and similar flooded models are compatible; Trojan AGM and SIND series are not.
Flow-Rite offers compatible hand pumps and electric watering pumps that thread directly onto the BG-U72V-7J fill port. An electric pump lets you water your entire battery bank in under 60 seconds without bending over the battery compartment -- ideal for full-timers and fleet operators who maintain multiple rigs.