Class A Motorhome Residential Fridge & Dual Rooftop A/C Solar Upgrade
How to replace 1,000 lbs of dead 6V AGM golf-cart batteries in a Class A motorhome with a 48V LiFePO4 bank and 2,400W–3,600W solar array capable of running a residential French-door fridge and two 15,000 BTU rooftop A/Cs off-grid.
1. Mobile Electrical & Roof Mounting Engineering Specifications
- 1Residential French-Door Refrigerator Math: Modern Class A coaches come with a 20 cu. ft. Samsung, LG, or Whirlpool 120V AC residential refrigerator + ice maker. While the fridge itself uses 1.6 to 2.2 kWh/day, leaving a massive 3,000W inverter turned on 24/7 adds 0.9 to 1.4 kWh/day in idle inverter tare loss—totaling ~3.2 kWh every 24 hours just to keep food cold.
- 2Weight Reduction on the Chassis: Eight 6V L16 lead-acid batteries weigh 960 lbs and deliver only 4.8 kWh of usable energy (at 50% DoD). Two 48V 14.3 kWh LiFePO4 wallmount/rack batteries weigh just 600 lbs total while delivering 28.6 kWh—6x more usable energy at 360 lbs less weight!
- 3Powering Dual 15,000 BTU Rooftop A/Cs on 50A Service: Equip both rooftop Dometic Penguin II or Coleman Mach units with Micro-Air EasyStart soft-starters so a dual-leg 50A inverter setup (or EG4 6000XP / Dual Victron MultiPlus-II 48/3000) runs both A/C compressors simultaneously without tripping.
2. Solar, Alternator & 30A/50A Transfer Wiring Schematic
Motorhome Fiberglass Roof (6x–8x 400W–450W Rigid Solar Panels mounted on heavy-duty aluminum feet secured with Dicor self-leveling lap sealant + structural fasteners).
Pass-Through Basement Bay → Dual MPPT Charge Controllers → 48V 14.3 kWh–28.6 kWh LiFePO4 Battery Bank.
50A 120V/240V Split-Phase Inverter-Charger wired directly between the 50A Shore/Generator Transfer Switch and Main 50A AC Breaker Panel.
3. Direct-Wholesale RV & Expedition Hardware Bill of Materials (BOM)
| Hardware Component | Engineering Specification | Est. Wholesale | Direct Source |
|---|---|---|---|
| EG4 6000XP Split-Phase 48V Inverter + 14.3kWh PowerPro / Indoor LFP | 6,000W 120V/240V 50A RV Service Output, 8,000W Dual MPPT Built-In | $4,698 | Check Price → |
| 2,400W Class A Motorhome Roof Solar Array (6x 400W Monocrystalline) | Generates 10–14 kWh/day in Southwest Boondocking | $1,560 | Check Price → |
| EcoFlow Delta Pro Ultra 7.2kW 50A RV Plug-and-Play System | Direct NEMA 14-50 50A Output, Zero Hardwiring Option | $4,999 | Check Price → |
RV & Overland Solar Engineering FAQ
Can I wire my Class A Onan Quiet Diesel generator to Auto-Start if the batteries ever hit 15%?
Yes! Both the EG4 6000XP and Victron Cerbo GX include programmable Two-Wire Auto-Gen-Start (AGS) dry-contact relays that automatically fire up your Cummins Onan generator at 15% SoC (outside campground quiet hours) and shut it off at 80% SoC.
How do I keep the motorhome’s 12V leveling jacks, slides, and lights working when upgrading to 48V?
Install a 48V-to-12V 60A–100A DC-DC converter feeding your coach 12V distribution panel, and retain one 12V high-cranking battery buffered for hydraulic leveling jacks and slide-out motors.