# 12 Volt Electrical Repair: Cost, Hours and Process in Hacienda Heights 12 volt electrical repair covers the DC side of a coach: the house battery bank, the fuse and distribution panel, the grounds, and every branch circuit feeding lights, pumps, fans, slide motors and control boards. Most complaints trace to a corroded ground or a failed converter output rather than to the appliance that quit working. ## Specifications - Price band: $285 to $5,000 plus - Shop hours: 1 to 20 plus hours - Turnaround tier: Systems and electrical - Insurance billable: no - Parts lead time: Fuses, breakers, terminals and wire in stock. Converter and panel assemblies 3 to 10 business days. - OEM brands: WFCO, Progressive Dynamics, Magnum, Lippert, Victron ## Voltage drop is the fault behind most 12 volt complaints A 12 volt system has almost no headroom. A 120 volt circuit can lose two volts and nothing notices. A 12 volt circuit that loses two volts has lost sixteen percent of everything it had, and the symptom shows up as a motor that runs slowly, a board that resets, or a light that browns out when something else switches on. That is why we measure under load rather than at rest. A resistive joint reads perfectly fine with a meter across it and no current flowing. Put twenty amps through it and the drop appears. Nearly every intermittent DC complaint that arrives here is a joint that passes an open circuit test and fails a loaded one. The usual offenders are the ground side, not the positive side. Coach grounds terminate on painted sheet metal, on a frame rail that has since been undercoated, or on a bus bar that was tightened by hand years ago. Owners chase the hot wire for hours because that is what the wiring diagram draws in color. - Battery post and cable lug corrosion, the single most common single point - Chassis and frame ground terminations on painted or coated metal - Distribution panel bus bar screws backed off by vibration - Crimped butt connectors from a previous repair, especially uninsulated ones - Harness chafe where a bundle passes a slide rail or a frame penetration - Undersized wire on an added circuit such as an inverter or a 12 volt refrigerator ## How a DC fault gets isolated in the shop The job starts with a state of charge and a load test on the bank, because a weak bank produces symptoms on every other system and there is no point diagnosing downstream of a bad supply. From there we read converter output, then panel voltage, then the branch, then the device. For a parasitic draw we put a shunt on the negative cable and pull circuits one at a time until the current drops. That is tedious and it is the only method that actually works. Radios, propane detectors, stereo memory, inverter standby, leveling controllers and antenna amplifiers all draw a small constant current, and the fault is usually one of them stuck awake rather than a mystery. For an intermittent fault we load the suspect circuit and then work the coach: cycle the slide, run the jacks, flex the entry step, open and close the compartment doors. A fault that only appears in motion has to be provoked in motion, and that is a bay activity, not a parking lot activity. ## What the diagnostic hour buys and what it costs This page uses the in depth diagnostic tier: one hour at $285, credited against an authorized repair. That hour is instrumentation time, and on a DC fault it is the highest value hour in the job. The alternative is replacing parts in sequence until the symptom stops, which is how a $300 problem becomes a $1,400 invoice with three good parts in the bin. After diagnosis, labor runs at the posted mechanical and electrical rate of $260 per hour. A single corroded ground is often inside the first hour. A chafed harness behind a slide, a failed converter and a panel that has to come out climbs toward the top of the band on this page. Parts on the DC side are inexpensive relative to labor, which is the opposite of most work in this building. That asymmetry means a careful diagnosis pays for itself faster here than anywhere else on the coach. ## Not included - Chassis engine electrical, starting and charging from the alternator is truck shop work, not coach work. - We do not diagnose electrical faults at a customer location. A DC fault needs a load bank and a bench. - Rewiring an entire coach is a separate line item rather than a repair. ## Questions **Why do my RV lights work on shore power but die on battery?** Because the converter is carrying the load and the bank is not. When you plug in, the converter supplies the 12 volt system directly, so weak or disconnected batteries are invisible. Unplug and the same circuits have to draw from the bank, and a bad cell, an open battery disconnect or a corroded main lug shows up instantly. The test is a load test on the bank, not a voltage reading. **What is a parasitic draw and how do you find it?** It is a small constant current that flattens a healthy battery bank over days rather than hours. Propane detectors, radio memory, inverter standby, leveling controllers and antenna amplifiers all contribute normally. A fault is one of them stuck on. We shunt the negative cable, read the resting current, then pull circuits one at a time until it drops. It is methodical and there is no shortcut. **How long does a 12 volt electrical repair take?** A single failed ground, fuse block or terminal is usually one to three hours and the coach goes home the same day if the bay is open. An intermittent fault, a chafed harness or a converter and panel replacement runs three business days to two weeks, mostly because the fault has to be provoked repeatedly before anyone can call it fixed. **Can you work on the chassis charging system too?** No. The alternator, starter and chassis engine harness are truck shop work and this facility does not take them on. What we do cover is everything on the coach side of the isolator: the house bank, the converter, the distribution panel and every branch circuit off it. If the fault turns out to be chassis side, you will hear that from us on day one rather than after a week. --- Source: https://ocrv.club/rv-service/12-volt-electrical-repair OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887 Phone (949) 799-3387. Email info@ocrvcenter.com. Serving Hacienda Heights and the surrounding area. 18.4 miles, 24 to 38 minutes via SR-60 west to Fullerton Rd, then south to La Palma Ave. In shop work only. All estimates are priced and credited against an authorized repair.