My 12V Charger Is Not Working on My Travel Trailer

by John Cagney Nash

A travel trailer's 12-volt, DC circuits rely on an onboard battery as a power source. That battery is charged by a hot wire from the tow vehicle -- when hitched and underway -- and by a 120-volt, AC converter charger when hooked up to a grid via a shore-power connection cord. The battery relies solely on the converter charger for power when the tow vehicle is disconnected from the travel trailer for extended periods. The travel trailer is left with no 12-volt appliances if the converter charger fails.

Set your voltage meter to read 120-volt AC, and test the power supply to the converter charger. Follow the meter manufacturer's instructions to ascertain that power is flowing to the live terminal of the charger. Check the fuse or circuit breaker protecting the converter- charger's circuit if power flow is not evident. Test along the circuit until a break is found, and repair the break.

Set your voltage meter to read 120-volt AC, and test the the neutral wire from the converter charger. It is important that the return makes an unbroken circuit to the neutral bus-bar of the fuse board or circuit breaker. Follow the same procedure to locate a break in the return circuit, and repair the break if one is found.

Listen to the converter charger. All units are fitted with a cooling fan; if no sound can be heard coming from the converter charger, an internal problem exists. Disconnect the shore power from the travel trailer, and disconnect the 12-volt battery. Remove the converter charger and take it to a recreational vehicle dealership for diagnosis and repair.

Consult the owner's manual of the converter charger, and determine if it has a reset control. Converter chargers are sometimes equipped with a breaker intended to protect their internal circuitry from power surges, and often these breakers do not self-reset. If a reset control exists, simply depress the button to reset the breaker.

Set the voltage meter to read 12-volt DC current; this usually means turning the function selector dial to 20 volts. Bridge the meter's probes across the converter-charger terminals, which connect to the battery or the fuse board. The charge typically reads greater than 12-volts if the converter charger is operating correctly. If it is not, disconnect the shore power from the travel trailer, disconnect the 12-volt battery, remove the converter charger and take it to a recreational vehicle dealership for diagnosis and repair.

Set the voltage meter to read 12-volt DC current, and bridge the meter's probes across the battery terminals. If the reading is less than at the converter charger terminals, a problem exists between the converter charger and the battery. Some travel trailer manufacturers install a heavy, inline-fuse or breaker in the hot, color-coded red wire; check to see that it is functional.

Remove the terminal connectors from the battery terminal, negative lead first. Clean inside the connectors and around the outside of the terminals with coarse sandpaper. Replace the terminals, positive first. If the current being delivered to the battery is above 12-volts and the negative wire is unbroken -- yet the battery still does not charge -- the battery is faulty and must be replaced.

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About the Author

John Cagney Nash began composing press releases and event reviews for British nightclubs in 1982. His material was first published in the "Eastern Daily Press." Nash's work focuses on American life, travel and the music industry. In 1998 he earned an OxBridge doctorate in philosophy and immediately emigrated to America.

Photo Credits

  • photo_camera motorcoach,motorhome,rv image by Greg Pickens from