PRO Charging System BFG72V Battery Fuel Gauge - 72V System. The new Pro Charging System's battery fuel gauge solves one of the most common complaints about battery status indicators currently on the market today. Most battery status indicators are not accurate and many are not reliable. Many employ old technologies. The new Pro Charging Systems Battery Fuel Gauge changes the paradigm. Think the old "Motorola Brick Phone" from the late 1980's versus today's I-Phone. The new Pro Charging System (PCS battery fuel gauge measures the battery's energy state with precision and accurately displays the information more like a traditional fuel gauge.