Redarc charger guide for vans and overland

What a Redarc charger does in real use

A Redarc charger is a DC DC charging device that moves energy from the vehicle to an auxiliary battery while holding the correct voltage and current for the battery chemistry. Instead of letting alternator voltage drift, the unit delivers a multi stage charge profile that covers bulk, absorption, and float. Many models also include a solar regulator, so the charger blends alternator and solar input and will often prioritize solar when the sun is strong.

Compared with a simple voltage sensing relay, a DC DC charger maintains proper voltage under load and with smart alternators that drop voltage during cruise. This matters with lithium iron phosphate batteries, which expect a precise charge curve to reach full capacity and maintain cell balance. The charger protects the starting battery from excessive load, prevents backfeeding, and helps both batteries live longer.

Solar integration is a central advantage. When a panel is connected, the charger’s MPPT tracking extracts more power during low light or partial shade than a basic PWM regulator. That extra efficiency translates to more energy harvested per day, which keeps fridges cold, inverters stable, and fans spinning without idling the engine.

Sizing and system planning

Start with your auxiliary battery capacity and daily energy use. A practical guideline is a charger output equal to about 20 to 40 percent of the usable amp hours of the house battery. For example, a 200 amp hour lithium bank might pair well with a 30 to 60 amp DC charger. Factor alternator capability and duty cycle. A high output alternator can support larger charge rates, but many stock alternators are not designed to sustain heavy loads for long periods.

Cable length and gauge affect voltage drop. Keep the charger close to the auxiliary battery when possible, use appropriately sized cable, and target less than three percent voltage drop at full load. Fuse both ends near the battery connections using properly rated ANL or MIDI fuses. Solid crimps or hydraulic crimp lugs with adhesive heat shrink outperform set screws in high vibration environments.

Mounting location and heat management matter. DC chargers generate heat under load. Provide airflow, avoid sealed compartments with no ventilation, and follow the manufacturer temperature derating guidance. Choose a location that stays cleaner and cooler than under hood spaces if the unit is not designed for engine bay temperatures. Look for an IP rating that matches your exposure to dust and moisture.

Solar array sizing should match daily consumption and the region where you travel. In sunny climates, a 200 to 400 watt array on a van roof works well for a single fridge, lights, device charging, and a water pump. In forested or winter conditions, add more panel capacity or accept that alternator charging will carry more of the load.

Charge profiles and battery chemistry

Set the charger for your chemistry. AGM and gel require lower absorption voltages than lithium. Lithium iron phosphate benefits from a firm bulk voltage and a short absorption period, with no need to float for long durations. If temperature compensation is available, enable it for AGM and gel. Lithium typically does not use negative temperature compensation and relies on a battery management system for protection.

Installation best practices

Plan the wiring path before drilling. Keep positive and negative runs together to minimize inductive loops, secure cables at regular intervals, and protect them in split loom or conduit. Sand paint off chassis ground points, use star washers, and coat with dielectric grease to limit corrosion. If a shunt based battery monitor is part of the system, route all negative loads through the shunt to get accurate state of charge.

Commissioning follows a simple sequence. Verify polarity with a multimeter, confirm fuses are correct, and check resting voltages on both batteries. Enable the charger, confirm input source detection, and watch current flow during the first bulk cycle. If solar is connected, test open circuit voltage of the array, then verify MPPT engagement once the charger sees the panel.

Troubleshooting quick list

• Alternator input low: confirm ignition sense on smart alternator vehicles and check voltage at the charger input under load.
• Thermal derating: add airflow or relocate the unit away from heat sources and confirm cable gauge is adequate.
• No solar input: verify panel polarity, measure open circuit voltage, and ensure the array matches the charger’s voltage window.
• Slow charging: inspect for voltage drop, loose grounds, or undersized wiring.

Safety and protection

Protect every positive conductor with the right fuse rating and place fuses close to the energy source. Secure batteries to prevent movement, provide ventilation for chemistries that require it, and keep chargers away from fuel lines or exhaust components. Label circuits and document settings so service is straightforward on the trail or at a shop.

How this fits in a complete van system

A well configured Redarc charger becomes the backbone of a reliable 12 volt ecosystem. It pairs with a smart battery monitor, a breaker panel for loads, and a solar array sized to your travel pattern. Set it up once, and the system silently refuels your house battery while you drive or camp in full sun, with safe charge rates and clean wiring that withstands corrugations and winter road salt.

If you are planning a purpose built rig, our team integrates DC charging with shore power, solar, and distribution so the system behaves like a single, simple power plant. Explore our recreational vans to see how we package power with storage, water, and interior layouts. For a one off specification, our custom build van path turns your use case into a finished electrical system. If you prefer a finance friendly platform path, review our mainstream vans options that start with vehicles at book value.

Strong power systems are not about bigger parts. They are about balance, correct settings, and safe installation. When those pieces line up, the charger does its job quietly and your attention stays on the road and the trail ahead.

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Ready for a dependable off grid power setup with solar and DC charging that just works? OZK Customs designs and installs complete electrical systems inside fully built vans with clean routing, clear documentation, and support at handoff. Tell us how you travel, and we will build the system around your life.