Stop removing individual vent caps and guessing at water levels. The Flow-Rite BG-U48V-7J Pro-Fill system replaces your existing vent caps with automatic shut-off valves interconnected by tubing, so you fill every cell to the correct level in a single operation -- no over-filling, no spills, no acid burns.
Deep-cycle flooded lead-acid batteries require regular watering to maintain capacity and lifespan -- but doing it cell by cell with a turkey baster or funnel is slow, messy, and easy to get wrong. Under-fill and you sulfate the plates; over-fill and you push acid out during charging, corroding terminals and battery trays.
The Flow-Rite Pro-Fill system solves all of that. Automatic float-valve shut-off valves seat into each cell opening (replacing the OEM vent caps). Flexible tubing links every cell together and routes to a single fill point. Attach a hose or hand pump, squeeze the trigger, and the system fills every cell to the precise manufacturer-specified level -- then stops automatically. Total fill time for a 48V battery bank drops from 15-20 minutes to under two minutes.
Float valve technology stops water flow at the correct electrolyte level in every cell simultaneously.
Valves thread directly into the existing vent-cap openings on Trojan Plus 6V and 12V batteries -- no drilling or modification.
All cells interconnected with flexible tubing; one attachment point fills the entire bank in one shot.
Consistent, correct fill levels prevent sulfation from low water and acid overflow from over-watering.
The BG-U48V-7J kit is purpose-built for a 48V battery bank using Trojan Plus-series 6V or 12V batteries. The kit includes:
A compatible hand pump or water delivery system is sold separately. Flow-Rite's single-hand trigger pump or gravity-fed bottle systems are designed to mate with the Pro-Fill coupling.
Trojan's own maintenance guidelines state that maintaining proper electrolyte levels is the single most impactful routine maintenance task for flooded deep-cycle batteries. Consistent watering with an automatic shut-off system eliminates the two most common watering errors -- under-fill and over-fill -- and removes the need to handle acid-coated vent caps each cycle.
This kit is designed for Trojan Plus-series flooded lead-acid batteries in a 48V bank configuration. Common compatible pairings include:
The "Universal" designation means the valves fit the standard Trojan Plus cell opening size and thread pitch without adapters. If your batteries are standard Trojan (non-Plus) or another brand, verify the vent-cap thread size before ordering -- a different Flow-Rite kit may be the correct fit.
Trojan Plus 6V golf-cart-style batteries are extremely common in RV house banks, off-grid cabins, and solar storage installations. A 48V bank (eight 6V batteries) is standard in many electric vehicle and larger solar systems. The Pro-Fill system is equally useful in any of these installations -- anywhere that watering access is awkward or the batteries are in a compartment that makes individual cap removal difficult.
Never use tap water to fill flooded lead-acid batteries. Minerals and chlorine in tap water accelerate plate corrosion and reduce battery capacity. Use only distilled or deionized water with this system. The Pro-Fill valves do not filter or purify incoming water.