Hymer Aktiv – 12V Lithium Battery Bank & Solar Upgrade

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Complete repair guide for the Hymer Aktiv – 12V Lithium Battery Bank & Solar Upgrade. Follow these steps to diagnose and fix the issue yourself.

Parts & Tools You’ll Need

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Step-by-Step Repair Guide

Step 1: Diagnose Existing Power System

Begin by disconnecting your existing 12V lead-acid battery and documenting all current electrical connections, including wire gauges, fuse ratings, and load requirements. Test your van’s alternator output voltage and amperage to ensure it can support the new DC-DC charger, and verify that your solar roof space can accommodate the 200W panel without obstructions or shade issues.

Step 2: Install ANL Fuse Holder Assembly

Mount the ANL fuse holder as close as possible to your LiFePO4 battery’s positive terminal, ideally within 18 inches, using a secure bracket on the battery box or adjacent wall. Connect the 4/0 AWG welding cable from the battery positive terminal to the fuse holder input, then insert the 200A ANL fuse to protect your entire electrical system from short circuits and overcurrent events.

Step 3: Mount LiFePO4 Battery Securely

Position your 100Ah LiFePO4 battery in the same location as your original lead-acid battery, using a purpose-built battery box or secure mounting bracket that prevents movement during driving. Ensure proper ventilation around the battery and keep it away from heat sources, then connect the negative terminal to a dedicated ground point on your van’s chassis using 4/0 AWG cable.

Step 4: Wire Victron SmartSolar Controller

Connect your 200W solar panel leads to the SmartSolar MPPT controller’s PV input terminals, following the manufacturer’s polarity markings carefully. Route the controller’s battery output cables to your bus bar system, positioning the controller in a ventilated, accessible location away from direct heat and moisture.

Step 5: Install Battery Monitor Integration Point

Mount the Victron BMV-712 display in an easily viewable location such as your dashboard or living area, then run the shunt cable from the monitor’s negative terminal to your main negative bus bar. This allows real-time monitoring of your battery state of charge, voltage, and current draw throughout your van.

Step 6: Connect DC-DC Charger to Alternator

Install the 40A DC-DC battery-to-battery charger in an engine bay location with adequate cooling and protection from moisture and vibration. Wire the charger’s input directly to your van’s alternator output using appropriately sized cable, and connect the output to your main positive bus bar, ensuring all connections are fused according to the charger’s specifications.

Step 7: Test Complete System Under Load

Power on your van and monitor the Victron BMV-712 display to verify that the lithium battery is receiving charge from both the alternator and solar panel under various conditions. Run a 30-minute load test using high-draw appliances like your heater or water pump to confirm that all components respond correctly and that voltage remains stable above 12.8V under typical usage.

Recommended Parts

PartLink
100Ah LiFePO4 drop-in lithium batteryView on Amazon
Victron SmartSolar MPPT charge controllerView on Amazon
Victron BMV-712 battery monitorView on Amazon
40A DC-DC battery-to-battery chargerView on Amazon
200W flexible solar panelView on Amazon
ANL fuse holder + 200A fuseView on Amazon
4/0 AWG welding cable (battery interconnect)View on Amazon
Bus bar / power distribution terminal blockView on Amazon