Battery Tender Charge N Start 4120 — 2-in-1 12V/4A Smart Charger & 1200A Jump Starter with Auto-Switch

The Charge N Start 4120 unites everyday charging with emergency starting capability in a single compact tool designed for cars, motorcycles, ATVs, boats and other 12V systems. Built from Battery Tender's decades of battery expertise, it monitors and maintains batteries while holding reserve jump-start power — ideal for garages, service vehicles, and roadside readiness.

How does the Charge N Start 4120 keep both batteries ready?

The unit features Auto-switch Technology that alternates charging between the vehicle battery and the internal jump starter battery. A microprocessor-controlled routine assesses state-of-charge and redirects current so neither battery is neglected.

• Automatic switching between vehicle and internal starter battery
• Smart 12V/4A multi-stage charging to avoid overcharge
• Temperature-compensated charging for consistent performance

Can it start my vehicle — and what are its limits?

The integrated 1200-amp jump starter delivers enough cranking power for many consumer vehicles: it will commonly start up to 6.0L gasoline and 4.0L diesel engines. It’s designed as a professional-grade emergency starter for most cars, trucks, SUVs, motorcycles and small boats.

• 1200A peak starting capability for quick engine cranking
• Rated for up to 6.0L gas and 4.0L diesel engines
• Heavy-duty copper-plated clamp jaws for reliable connection

What safety features protect me and my vehicle?

Safety is built into the Charge N Start 4120 with spark-proof clamps, reverse-polarity protection, and microprocessor control to avoid improper charging. These safeguards let you connect with confidence even in low-light or stressful roadside situations.

• Spark-proof and reverse polarity protection for safe hookup
• Microprocessor-managed charging and thermal compensation
• Built-in LED emergency light for visibility during use

What accessories and extras come in the box?

The package includes everything needed for immediate use and storage: the Charge N Start 4120 unit, a set of heavy-duty smart clamps with copper-plated jaws, and a premium storage case to protect the gear when not in use.

• Charge N Start 4120 unit with internal jump battery
• Heavy-duty smart clamps and integrated connectors
• Premium storage case and built-in LED light; 1-year warranty

Who this is for: The Battery Tender Charge N Start 4120 is aimed at drivers, riders, and technicians who want a compact, dependable two-in-one solution for daily battery maintenance and emergency starts. If you maintain multiple vehicles, travel seasonally, or need a garage-ready backup that reduces clutter while delivering professional-grade starting power, this unit is a practical choice.