RV Chargers & Maintainers

Matching a charger to your setup

The right charger really depends on your power source and how the battery gets used. The main types sort out like this.

• Shore-powered multistage chargers. A unit like the Xantrex TRUEcharge3 (12V/40A, three banks) runs bulk, absorption, and float stages, so the battery charges fast and then holds without boiling off electrolyte. Multistage is the difference between a charger and a battery cooker.
• Trickle maintainers. For a rig in storage, a Battery Tender 800 (12V, 800mA, fully waterproof) holds a battery at full charge through the off-season without overcharging. Small output, long battery life.
• DC-DC chargers. Newer tow vehicles with smart alternators will not reliably charge a trailer battery on their own. A REDARC changeover relay and DC-DC charger force a proper charge into the house bank while you drive.
• Solar maintainers. A Battery Doctor 5W amorphous panel trickles a slow top-up with no shore power at all, handy for a battery sitting on a lot in the sun.
• Relays and sensors. A Blue Sea Automatic Charging Relay (120A) auto-combines banks when one is charging, and a temperature sensor tells the charger to ease off in heat and push harder in cold.

Charge output only helps if the battery is healthy and the charger matches its chemistry. For off-grid top-ups, pair a charger with a full solar setup, and use a disconnect switch to isolate the bank before you work on any of it.