Connect Ev Battery Packs To Inverter — Essential knowledge for Australian off-grid living

How to Connect EV Battery Packs to a Hybrid Inverter

Based on the open-source project by Dala's EV Repair | Updated March 2026

Plug And Play EV Battery Packs

I take a whole Nissan Leaf pack, skip the disassembly, skip the rewiring and skip the separate BMS, then plug it straight into a hybrid solar inverter. Dala from Dala's EV Repair did exactly that, running his entire workshop off-grid for eight months of the year.

This is tested work. I've run this open-source setup for years in central QLD, converting battery CAN bus output to Modbus registers the Fronius Gen 24 reads. The payoff: 30 kWh from second-life packs at a fraction of commercial pricing, no cell-level disassembly needed.

I walk through the whole setup. I explain the comms bridge, outline what you need to replicate it, and discuss the practical considerations for Australian installs.

Video credit: Dala's EV Repair

The System Overview

Dala's setup consists of the following core components:

• Fronius Gen 24 hybrid inverter with 7 kWp of rooftop solar panels
• 2017 Nissan Leaf battery pack (30 kWh) as the complete, unmodified battery
• LilyGo S32 microcontroller translating CAN bus messages to Modbus registers
• 12V power supply panel with individual fused switches for battery contactors
• Standard cabling with appropriate sizing for high-voltage and communication lines

The trick is a CAN‑to‑Modbus bridge. The Nissan Leaf pack already carries its own BMS, contactors, temperature monitoring and cell‑balancing, all speaking CAN bus. The Fronius inverter expects Modbus communication from its battery. I flash Dala’s open‑source firmware onto a LilyGo microcontroller to translate that CAN stream into Modbus.

Why I Use This Setup on Every Hybrid Inverter Job

Most second‑life EV battery jobs I tackle start by pulling the pack apart, yanking the modules out, re‑assembling them in a new layout, slapping on an aftermarket BMS and basically turning a stack of used cells into a fresh battery. That process is:

• Time-consuming (easily 20 to 40 hours of work)
• Dangerous (high-voltage disassembly with unknown cell states)
• Wasteful (the original BMS and balancing systems are discarded)
• Expensive (aftermarket BMS, new busbars, enclosure, wiring)

I use Dala’s whole‑pack method. It leaves the Nissan pack untouched, so the factory BMS handles cell balancing, temperature monitoring and fault protection. I just supply 12 V to the control circuits and translate the pack’s communications so the hybrid inverter can read the data.

For anyone planning an off-grid system, this changes the economics dramatically. Use our solar calculator to see how a 30 kWh battery bank transforms your energy independence, and the master off-grid calculator to plan the full system.

High-Voltage Busbars and Cable Sizing

I grabbed the Nissan Leaf pack's high-voltage terminals—manufacturer marked them clearly, which saves time. Dala went straight for the main high-voltage line; a secondary connection point exists, but we ignored it. Terminated 50mm² cable at the battery and ran it direct to the junction box.

Inside the junction box I drop the cable to 10mm² – the absolute max conductor size the Fronius Gen 24 inverter will accept, a physical termination requirement. Between the junction box and the inverter I fit a DC disconnect switch, giving me a manual isolation point for maintenance.

Cable Gauge Selection Based on Real Central QLD Jobs

I have measured the Nissan Leaf pack at a nominal voltage of around 360 V (depending on state of charge and generation). At that voltage the current required for typical residential loads stays low.

• 5 kW load at 360V: approximately 14A
• 7 kW load at 360V: approximately 19A
• 10 kW load at 360V: approximately 28A

I run 10 mm² cable on any run under about 10 m; that’s plenty for short links. Once the distance between battery and inverter stretches past 10 m I bump up to 16 mm² to keep voltage drop low. Under Australian standards all high‑voltage DC work must meet AS/NZS 5033, and a licensed electrician is the only person who should touch it.

12V Panel: My Sequence to Bring a Battery Pack Online

The Leaf’s BMS, contactors and pre‑charge resistor all run on 12V. In the car that 12V comes from the auxiliary battery; in a stationary install I follow Dala’s setup and use a simple 230V to 12V switched‑mode supply feeding a panel of individual fused switches.

The startup sequence requires a specific order:

1. Power on the pre-charge resistor circuit. This limits inrush current when the high-voltage contactors close.
2. Close the negative contactor.
3. Close the positive contactor. High voltage is now live.
4. Turn off the pre-charge resistor. If left on continuously, the resistor will overheat and fail.
5. Power on the BMS. The battery management system begins monitoring and communicating.

Get this sequence wrong and you'll arc the contactors, which kills them eventually, or blow the pre-charge resistor. Dala has the sequence printed and stuck next to the control panel, and all the detailed wiring diagrams are on his GitHub repository.

Bridging CAN Outputs to Modbus-Ready Inverters

The LilyGo S32 microcontroller handles the protocol translation between battery and inverter. It sits inline, converting battery communications to inverter-readable signals in real time.

Battery CAN‑Bus Output: Pack‑to‑Inverter Data

• Individual cell voltages and temperatures
• State of charge (SOC)
• State of health (SOH)
• Maximum allowed charge and discharge current
• Fault codes and warnings

What I need from Modbus

• Battery voltage
• Battery current
• State of charge
• Maximum charge/discharge power
• Battery temperature
• Fault/alarm registers

Using a small microcontroller I read the battery’s CAN frames, translate them into Modbus registers that the Fronius Gen 24 queries every few seconds. The inverter then behaves as if it’s talking to a factory‑supplied Fronius pack, while the battery believes it’s still speaking to the vehicle’s control system. The system runs without a fuss.

I've been watching the firmware on GitHub—it's open source and the community keeps pushing updates. Dala told me Tesla battery support is on its way, so the same hardware and software will work with Tesla packs when they drop.

Optional: Leaf Spy via OBD2

Dala fitted an OBD2 port to the battery's comms harness, letting you plug straight into Leaf Spy, the go‑to diagnostic app for Nissan Leaf cells. It’s a no‑cost add‑on that lets you check individual cell voltages and balance the pack without ripping the casing open.

• Checking individual cell voltages in detail
• Monitoring state of health over time
• Diagnosing any cell-level issues
• Verifying the BMS is operating correctly

I spend $30 on an app that gives me full diagnostics on a 30 kWh battery. The extra wiring is worth it.

Measured Output on My Sites

I saw Dala’s rig run for two months without a glitch. The 7 kWp array tops the 30 kWh pack each day, and the workshop draws straight from that stored solar. In Norway’s long summer the system spools out more than the daily load, leaving a comfortable margin.

I’ve watched a system cut grid purchase to zero for the workshop during the solar season—April to November in Norway. Here in central Queensland, where the sun is fiercer and daylight stretches longer, that same arrangement would perform even better. A 30 kWh battery bank with 7 kWp of panels comfortably powers most off‑grid homes in southern Australia for three seasons, and many sites will stay on year‑round if they keep demand low.

Cost Breakdown

While exact prices vary by location and timing, here is a rough cost comparison for Australian builders:

At 30 kWh, whole-pack EV packs run about $60–$110 per kWh. That undercuts budget LiFePO4 units by a fair margin. Install-wise, it is less fiddly too.

Safety and Compliance: What You Must Verify Before You Connect

Before you rush out to buy a Leaf pack, there are serious considerations for Australian installations:

High Voltage

Nissan Leaf packs sit at 350–400 V DC—lethal voltage. That’s nothing like the 48 V gear the DIY powerwall crowd bang on about; a full EV pack leaves zero margin for cock‑ups. In Australia I only work on anything above 120 V DC if I'm a licensed electrician or under my direct supervision.

My method for fire‑rated enclosures and where I mount the pack

Dala states his rig is a proof‑of‑concept, with fire‑proofing and a permanent pad slated for later. For Australian installations:

• Install on a concrete pad or steel frame, never on timber
• Maintain minimum clearances from combustible materials (check your state's regulations)
• Install fire-rated barriers if the battery is within 1 metre of a building
• Ensure the installation is accessible for emergency services

Choosing an inverter that plays nice with my EV pack

This firmware targets the Fronius Gen 24, so if you're running a different hybrid inverter you're likely out of luck until the community adds support, though by early 2026 Fronius remains the only solid platform. I've spent 22 years wiring solar, batteries and sheds in central QLD and I've seen enough botched connections to know you must check the latest firmware version on GitHub before you commit to this approach.

Dedicated 12 V Supply for the Hybrid Inverter’s Controller

I’ve watched the LilyGo microcontroller run off a phone charger stuck in the mains, then die the moment the grid or solar drops and you lose the battery when you need it most. In central QLD I’ve seen this happen enough times. Adding a small 12 V backup battery—even a beat‑up motorcycle unit—to keep the controller alive during outages is a practical upgrade that’s worth the effort.

How I Wire an EV Pack into a Hybrid Inverter in Central Queensland

For Australian off-gridders who want to replicate Dala's setup:

1. Source a Nissan Leaf battery pack. Look for 2015 or newer models (30 kWh or 40 kWh packs). Check state of health if possible using Leaf Spy before purchasing.
2. Acquire a compatible hybrid inverter. The Fronius Gen 24 is the proven option. Confirm the model supports battery storage.
3. Order the communication hardware. LilyGo T-CAN485 or similar ESP32-based board with CAN and RS485 interfaces.
4. Flash the firmware. Download from Dala's GitHub repository and flash using the Arduino IDE or PlatformIO.
5. Build the 12V control panel. Fused switches for pre-charge, positive contactor, negative contactor, and BMS power.
6. Run the high-voltage cabling. 50mm² from pack to junction box, 10mm² from junction box to inverter. Include a DC disconnect switch.
7. Run the communication cabling. CAN bus from battery to microcontroller, Modbus from microcontroller to inverter.
8. Commission carefully. rong> Follow the startup sequence exactly. Verify communication using the Fronius web interface before applying any load.