Battery Tender® 4-Bank 12V 1.25 Amp Battery Charger and Maintainer

Four vehicles. One charger. The Battery Tender® 4-Bank 12V 1.25 Amp is the standard for multi-vehicle storage — four completely independent ISM (Infinite Sequential Monitoring™) charging circuits, each running at full 1.25 Amp output, simultaneously maintaining up to four 12V batteries in any combination of charge state. For collectors, dealerships, rental operations, and households with multiple vehicles in seasonal storage, the 4-Bank is the single infrastructure solution for the entire fleet.

Four Independent Banks — Not a Splitter

The Battery Tender® 4-Bank does not divide output across connected batteries. Each of its four banks is a complete, independent 1.25 Amp charging circuit with its own ISM algorithm reading its own battery's state. Bank 1 can be recovering a deeply discharged battery at full 1.25 Amp bulk charge while Banks 2, 3, and 4 are simultaneously in float maintenance on fully charged batteries — four different charge stages, four different batteries, one unit. This is the critical distinction from split-output adapters that divide a single charger's output and reduce per-battery amperage.

ISM on All Four Banks Simultaneously

Each bank independently runs the complete 4-stage ISM algorithm:

• Initialization — Individual health check and polarity confirmation for each battery before current flows on that bank
• Bulk Charge — Full 1.25 Amp output restores depleted capacity on that bank independently
• Absorption — Current tapers for each battery individually as it approaches full charge, preventing overcharge regardless of neighboring bank states
• Float Maintenance — Each battery held at peak voltage 24/7, indefinitely, independent of all other banks

Every battery connected to the 4-Bank receives the same intelligent charging it would receive from four individual Battery Tender® Plus units running in parallel.

Compatible Battery Types and Sizes

Each bank: 12V lead-acid batteries from 14Ah to 80Ah. All lead-acid chemistries: flooded, AGM, gel cell, and sealed maintenance-free.

Fleet, Collection, and Commercial Applications

• Multi-motorcycle and powersports vehicle garages
• Classic and collector vehicle storage in any four-vehicle combination
• Powersports dealership demo and inventory battery maintenance
• Rental and fleet operation battery maintenance
• Marina and boat storage with multiple 12V battery systems
• Equipment yards with multiple seasonal vehicles
• Any facility requiring simultaneous independent maintenance of four 12V batteries

One Unit vs. Four

Four individual Battery Tender® Plus units maintain four batteries with identical results — but require four power outlets, four sets of cables, four units of wall space, and four separate product purchases. The Battery Tender® 4-Bank delivers the same independent per-battery ISM performance from a single wall outlet, a single unit footprint, and four dedicated output cables. For storage rooms, equipment bays, and facilities where outlet count and cable management matter, the consolidation advantage is significant.

Automatic Temperature Compensation

All four banks automatically adjust charge voltage based on ambient temperature — each bank delivering the correct voltage to its battery regardless of weather or storage conditions. Correct charging from winter cold to summer heat without manual adjustment on any bank.

Safety Features

• Spark-proof connection on each bank — no current flows until polarity and connection are confirmed correct per bank
• Reverse polarity protection per bank — incorrect connection on one bank does not affect the remaining three
• Short-circuit protection per bank — individual fault isolation
• ETL and CETL certified

Four Batteries. Zero Spring Failures.

The cost of seasonal battery failure multiplies across a four-vehicle fleet — four dead batteries means four replacements, four installation sessions, and four vehicles not ready when the season opens. The Battery Tender® 4-Bank prevents all four failures simultaneously. Sulfation — the permanent, irreversible hardening of lead sulfate on battery plates — is the cause of every stored battery failure. ISM on all four banks prevents it entirely through continuous float maintenance, consistently extending battery life from 2–3 years to 5 years or more across every vehicle in the fleet.

Four vehicles maintained. One unit. Year after year.

2-Year Limited Warranty | DeLand, Florida Since 1965