# Electrical, Power and Generators > Twelve volt and one hundred twenty volt diagnosis, battery banks, solar, inverters, wiring and Onan generator service, performed in shop. Source: https://ocrv.info/services/electrical-power-and-generators Power problems are the least forgiving repairs on a coach because nothing else works until they are solved. The furnace will not light without twelve volts at the board. The absorption refrigerator will not switch modes. The slide stops halfway out. Owners usually arrive describing one dead accessory, and testing almost always reveals a shared feed, a shared ground or a bank that cannot hold voltage under load. Fixing the accessory alone puts the coach right back in the bay two months later. This shop treats the electrical system as two separate networks that meet at a handful of transfer points. The direct current side runs off the house bank and the converter. The alternating current side runs off shore power, the generator or the inverter, whichever the transfer switch has selected. Confusing the two is the single most common reason a repair gets misdiagnosed elsewhere. We test each network on its own terms before looking at how they hand off to one another. Owners drive in from Eastvale by way of SR-71 to SR-91, roughly twenty miles, and the vehicle stays here until the system is verified end to end. All work happens inside the 35,000 square foot facility with the coach on shore power, on generator and on battery in turn. Load banking, clamp meter readings, thermal checks on lugs and a written record of every measurement come standard, because a power fault that is not measured is a power fault that comes back. ## Why Twelve Volt and Shore Power Faults Get Misdiagnosed A voltmeter at rest lies constantly. A house bank can sit at 12.7 volts with the coach quiet and still sag to 10.8 the moment a slide motor pulls current. Resistance hides in loose lugs, crimped-over strands, corroded ring terminals and undersized wire that somebody added during a previous upgrade. None of that shows on a static reading. The only honest measurement is voltage drop taken across each junction while the circuit is carrying its real load. The alternating current side fails differently. A pedestal breaker that trips only under air conditioning load, a transfer switch with pitted contacts, a neutral that has gone loose inside the main panel: these produce heat before they produce an outage. We use a clamp meter on each leg and an infrared reading on every lug and breaker while the coach runs its full load. Heat is the tell. Finding it before it browns the insulation is the whole point. - Voltage drop measured under load at every junction, not at rest - Separate test passes on shore, generator and inverter sources - Infrared scan of panel lugs, breakers and transfer switch contacts - Clamp readings on both hot legs to expose imbalance - Bank capacity verified with a load test, not a surface reading ## What Belongs in This Category and What Does Not Everything downstream of the house bank and everything downstream of the shore inlet belongs here. That includes converters, inverters, solar controllers, distribution panels, automatic transfer switches, generator sets from Onan and Cummins, twelve volt lighting, pumps, fans, slide and jack motors, monitor panels and the wiring harnesses that tie them together. Battery bank replacement covers flooded lead acid, AGM and LiFePO4 configurations, including the bus bar and cabling changes a lithium conversion actually requires. Chassis work has a boundary. Onboard generator service is squarely in scope and always has been, including carburetor and fuel system work, brush and slip ring replacement, control board diagnosis and load bank testing. Vehicle engine and transmission work is not something this shop performs. If a fault traces past the generator set into the coach powertrain, we document what we found and hand the vehicle back with the diagnosis in writing rather than opening work we do not do. ## Services in this category - [12 Volt Electrical Repair](https://ocrv.info/services/electrical-power-and-generators/electrical-12-volt-repair): Direct current fault finding across house feeds, grounds, fuse panels, lighting, pumps and motors, with voltage drop testing on every suspect circuit. Range $285 to $5,000+, 1 to 20 hours. - [120 Volt Electrical Repair](https://ocrv.info/services/electrical-power-and-generators/electrical-120-volt-repair): Alternating current repair covering inlets, panels, branch circuits, receptacles and ground fault protection, with thermal and load testing on every leg. Range $285 to $5,000+, 1 to 20 hours. - [Battery and Charging Systems](https://ocrv.info/services/electrical-power-and-generators/battery-and-charging-systems): House bank testing, chemistry selection, cabling and charge source correction so the pack actually reaches full and holds through a night. Range $500 to $5,500, 2 to 10 hours. - [Solar Panel Installation](https://ocrv.info/services/electrical-power-and-generators/solar-panel-installation): Roof array design, watertight mounting, MPPT control and bank integration sized against measured consumption rather than a catalog number. Range $1,500 to $12,000+, 8 to 40 hours. - [Inverter and Converter Repair](https://ocrv.info/services/electrical-power-and-generators/inverter-and-converter-repair): Diagnosis and replacement of converters, inverters and inverter chargers, including transfer behavior, charge profiles and cabling sized to the load. Range $750 to $4,500, 3 to 14 hours. - [Wiring and Fuse Box Repair](https://ocrv.info/services/electrical-power-and-generators/wiring-and-fuse-box-repair): Panel rebuilds, harness repair, correct conductor sizing and overcurrent protection for coaches carrying years of undocumented modifications. Range $400 to $5,500, 2 to 22 hours. - [Generator Service and Repair](https://ocrv.info/services/electrical-power-and-generators/generator-service-and-repair): Onboard generator service, fuel and ignition work, control board diagnosis and load bank testing so the set carries its rated load under heat. Range $400 to $8,500+, 2 to 35 hours. - [Shore Power and Transfer Switch](https://ocrv.info/services/electrical-power-and-generators/shore-power-and-transfer-switch): Inlet, cord, protection and automatic transfer switch work so the coach selects sources cleanly and nothing overheats at the handoff. Range $285 to $1,500, 1 to 6 hours. ## Frequently asked questions ### Can one visit cover both the twelve volt and the shore power side? Yes, and usually it should. The two systems share a converter, a transfer switch and often a ground bus, so a fault on one side frequently produces symptoms on the other. Scheduling both together means the coach only gets torn down once. Panel covers come off, the bank comes out for load testing, and the alternating current legs get scanned during the same bay time. ### Do you work on generators or only on the coach wiring? Generator sets are a core part of this category. Onan and Cummins units get carburetor service, fuel pump and filter work, brush and commutator inspection, oil and air service, control board diagnosis, exhaust and mount repair, and load bank verification before the unit leaves. A generator that starts but will not carry two roof air conditioners has a fault worth finding, and load banking is how it gets found. ### How far is the shop from Eastvale and do I need to drop the coach off? The facility sits at 23281 La Palma Ave in Yorba Linda, roughly twenty miles from Eastvale by way of SR-71 south to SR-91 west. Green River Road is the usual alternate when the 91 backs up. All electrical work is performed in shop, so the vehicle stays with us. Simple circuit repairs often finish inside a day. Bank replacements and solar builds take longer. ### Will a lithium conversion work with the converter already in my coach? Frequently not. Many older converters use a lead acid charge profile that never reaches the absorption voltage a LiFePO4 bank expects, so the pack sits chronically undercharged. Others push an equalization stage that lithium chemistry does not tolerate. We check the converter model, the alternator charge path, the bus bar amperage and the cable gauge before quoting a conversion, then list what actually needs to change. ### What does an electrical diagnosis cost before any repair is authorized? Diagnostic time bills at the posted diagnostic rate with a one hour minimum, and that time is applied as a credit against an authorized repair. RV systems estimates covering electrical, generators and related equipment carry a separate posted charge that is also credited. Published price bands for each service in this category appear on the individual service pages and on the prices page. --- OCRV Center. 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. info@ocrvcenter.com. Serving Eastvale, California in Riverside County, about 20 miles from the shop. All work is performed in shop at the Yorba Linda facility. No mobile, roadside or on-site service is offered. Scope is body, paint, structural, fiberglass, interior and vehicle systems work. Engine rebuilds, transmission rebuilds, drivetrain work, DOT inspections and emission testing are not performed.