Complete repair guide for the Thor Tranquility – 12V Lithium Battery Bank & Solar Upgrade. Follow these steps to diagnose and fix the issue yourself.
Parts & Tools You’ll Need
- 100Ah LiFePO4 drop-in lithium battery
- Victron SmartSolar MPPT charge controller
- Victron BMV-712 battery monitor
- 40A DC-DC battery-to-battery charger
- 200W flexible solar panel
- ANL fuse holder + 200A fuse
- 4/0 AWG welding cable (battery interconnect)
- Bus bar / power distribution terminal block
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Step-by-Step Repair Guide
Step 1: Diagnose Current System & Safety
Before beginning any work, disconnect the negative terminal of your existing 12V battery and allow all systems to power down completely for at least 5 minutes. Inspect your current battery setup, noting the amperage capacity, condition of existing cables, and any corrosion at connection points that could affect your new lithium system’s performance.
Step 2: Install Battery Disconnect Switch
Mount the ANL fuse holder with a 200A fuse directly to the positive terminal of your new LiFePO4 battery, positioning it within 18 inches of the battery as close as safely possible. This critical safety component protects your entire electrical system from short circuits and allows you to safely isolate the battery bank during maintenance or emergencies.
Step 3: Connect Primary 4/0 Cables
Run 4/0 AWG welding cable from the fused ANL holder to your main bus bar, keeping the cable routing away from heat sources and sharp edges with proper conduit protection. Strip ½ inch of insulation from each cable end and crimp heavy-duty lugs rated for 4/0 gauge, ensuring all connections are finger-tight plus one additional quarter turn with a wrench.
Step 4: Mount Victron SmartSolar Controller
Install your Victron SmartSolar MPPT charge controller in a well-ventilated location away from moisture, ideally near your solar panel connection point to minimize wiring runs. Ensure the controller has at least 4 inches of clearance on all sides for proper heat dissipation and is mounted at a slight angle to prevent water accumulation.
Step 5: Wire Solar Panel & Controller
Connect your 200W flexible solar panel to the SmartSolar controller’s PV input terminals using appropriately sized solar-rated cable (typically 10 AWG), ensuring positive and negative leads match the controller’s polarity markings. Route the controller’s battery output cables (sized for your system amperage) directly to your bus bar, bypassing any other components in between.
Step 6: Install Battery Monitor & DC-DC
Mount the Victron BMV-712 battery monitor between your battery bank and the main bus bar using the supplied shunt, following the manual’s precise wiring diagram for accurate monitoring. Install your 40A DC-DC battery-to-battery charger in-line with your vehicle’s alternator circuit, allowing your engine’s charging system to supplement your lithium bank during driving.
Step 7: Test System Operation & Settings
Power on the system and use the Victron app to verify that your SmartSolar controller is detecting the solar panel, the BMV-712 is showing accurate state of charge, and the DC-DC charger is responding to alternator input. Run your van’s engine for 15 minutes to confirm the battery-to-battery charger is functioning, then monitor the system for 24 hours under normal solar exposure to ensure all components are operating within specified parameters.
Recommended Parts
| Part | Link |
|---|---|
| 100Ah LiFePO4 drop-in lithium battery | View on Amazon |
| Victron SmartSolar MPPT charge controller | View on Amazon |
| Victron BMV-712 battery monitor | View on Amazon |
| 40A DC-DC battery-to-battery charger | View on Amazon |
| 200W flexible solar panel | View on Amazon |
| ANL fuse holder + 200A fuse | View on Amazon |
| 4/0 AWG welding cable (battery interconnect) | View on Amazon |
| Bus bar / power distribution terminal block | View on Amazon |