For intelligent charging for both modern and vintage batteries, the Battery Tender PowerTender 4 Amp delivers dependable performance across 6V and 12V systems with full support for lead-acid and Lithium chemistries. Designed with ISM (Infinite Sequential Monitoring), it continuously adjusts charging stages to maintain optimal battery health from recovery through long-term storage maintenance. With 4 Amp output, this charger significantly reduces recharge time compared to low-amp maintainers, making it ideal for vehicles that need quicker turnaround or larger batteries that require stronger charging current. A manual voltage and chemistry selection system ensures the correct charging profile is applied for each battery type. Engineered for versatility, this dual-voltage unit supports everything from classic 6V vehicles to modern 12V automotive, marine, and powersport applications. Features:• Selectable 6V / 12V charging output• 4 Amp fast charging performance• Supports Lithium and lead-acid batteries• ISM multi-stage charging technology• Automatic float maintenance modeSpecs:• Output: 6V / 12V @ 4 Amps• Battery Types: AGM, GEL, Flooded, Sealed Lead-Acid, LiFePO4• Supported Battery Range: 14Ah â 100Ah• Input: 120V AC, 50/60Hz• Weight: 1.35 lbs (charger only)• Dimensions: 3.86" x 1.87" x 8.3" Maintains vehicles during storage 4 Amp fast battery charger ISM smart charging system | PowerTender 4 Amp 12V/6V BC and Maintainer