40A 12V→12V Compact DC-DC Battery-to-Battery Charger with Solar Input

  
By Photonic Universe
Minus Plus

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40A 12V→12V DC-DC Battery-to-Battery Charger with Integrated MPPT Solar Input

This high-performance 40A DC-DC charger allows a 12V leisure or auxiliary battery to be charged from a 12V starter battery or alternator, and also features a built-in MPPT solar input for charging from solar panels when parked. Combining two charging systems in one compact, efficient unit simplifies installation and extends your off-grid runtime — ideal for campervans, motorhomes, caravans and boats.

The intelligent multi-stage charging program ensures each connected battery type receives the correct voltage and current profile for optimum life and performance. With one-button programming, advanced protections, and continued charging even under load, the DCDC-40A delivers professional-grade functionality in a user-friendly format.

Key Features

  • Dual-input operation: charges from alternator or solar panel (up to 40A) with automatic input switching.
  • Integrated MPPT solar controller: maximises solar efficiency and activates automatically when battery-to-battery charging is not required.
  • Multi-stage smart charging: precise charging for Lead Acid, AGM, Gel, Calcium and Lithium-ion batteries for longer lifespan and performance stability.
  • One-button battery type selection: quick configuration with memory retention even after power loss.
  • Safe unattended operation: built-in protection against overload, overheating, over-voltage, reverse discharge and short circuit.
  • Supports charging under load: powers 12V appliances while maintaining battery charge stability.
  • Ignition or voltage-sensing control: automatically starts and stops charging with engine operation or based on battery voltage levels.
  • Deep discharge recovery: capable of restoring batteries with output voltage as low as 2.0V.
  • LED indicators: show charge stage, power source and selected battery type for clear visual feedback.

Technical Specifications

Battery input voltage 12.5 – 16.0 V
Maximum charging current 40 A
Solar input voltage 16 – 25 V
Maximum solar input current 40 A
Minimum target battery voltage 2.0 V (recovery)
Bulk charge voltage 14.7 V (AGM/Gel), 14.4 V (Lead Acid), 15.4 V (Calcium), 14.4 V (Li-ion)
Float charge voltage 13.5 V
Recommended battery capacity 60 – 600 Ah
Dimensions (L × W × H) 307 × 198 × 45 mm
Weight 1.2 kg
Warranty 1 year

Compatibility & Installation

Suitable for any 12V battery system, including Lead Acid, AGM, Gel, Calcium and Lithium-ion types. Not compatible with 24V systems or mixed-voltage setups. Use correctly rated cabling and fuses, and ensure the charger is mounted in a ventilated location. Ignition and voltage-sensing control options make it adaptable for a wide range of vehicle and marine installations.

Documents Available

Installation and user guide available for download