Reddit reviews Battery Tender 4-Bank: 12V, 1.25 Amp Battery Charger - 12V Battery Charging Bank with 4 Ports - Simultaneously Charges and Maintains Up to Four Batteries - 022-0148-DL-WH

4 BANK CHARGER: Charge and maintain up to four 12 volt batteries simultaneously, each at its proper storage voltage without the damaging effects that typical trickle chargers can cause by overchargingCONNECT AND FORGET: Cutting edge Battery Management System technology automates the charge for your powersports by fully charging your battery, then goes into float mode to maintain an optimal chargePOWERSPORT COMPATIBLE: First fully automatic, constant current battery charger designed to charge and maintain up to four 12v or 6v batteries at once for your motorcycle, ATV or UTV, PWC, or scooterMONITOR POWER LEVELS: Solid state two-color LED light indicates the state of the charge and if the battery voltage drops too far under load, ISM adaptive charging will resume full charger output powerSAFE AND SECURE: Our multiple port battery bank is spark-proof during lead connection and automatically detects reverse polarity via microchip to ensure a correct connection before providing power