How to set up a proper LiFePO4 leisure battery system in your van — solar, DC-DC charging, wiring, and everything in between.
If you're planning to live in your van full-time, a proper 12V lithium leisure battery system is the upgrade that changes everything. Here's the honest case for why it beats a portable power station for full-time van life — and how the whole thing actually works.
A Jackery (or similar portable power station) is perfect for beginners and weekend van lifers. But once you're living in your van full-time, you'll quickly hit its limits: fixed capacity, can't run high-draw 12V appliances directly, harder to expand, and not designed to sit at 100% charge permanently.
A proper 12V system is wired permanently into your van. Your leisure battery stores the power, solar panels top it up during the day, and your alternator charges it while you drive. You can run a 12V compressor fridge directly, power a proper fuse box, and expand the system later by adding more batteries or panels.
Solar Panel: Converts sunlight into DC electricity. On a good sunny day in Europe, a 200W panel produces 150–190W in real conditions. It sends this power to the MPPT controller.
MPPT Solar Charge Controller: The clever device that extracts the maximum available power from your solar panels and safely charges the battery at the correct voltage and current. MPPT (Maximum Power Point Tracking) is significantly more efficient than older PWM controllers — especially in partial shade or cloudy conditions.
12V LiFePO4 Leisure Battery: Your main energy store. LiFePO4 (lithium iron phosphate) is the chemistry of choice for van life — safe, long-lasting, and 80–90% of its rated capacity is usable, versus only 50% for AGM lead acid.
DC-to-DC Charger (B2B Charger): Charges your leisure battery from your van's starter battery while the engine is running. Essential — a simple split charge relay is NOT suitable for lithium batteries and can damage your alternator without a proper DC-DC charger.
12V Fuse Box / Distribution Board: Distributes 12V power from the battery to all your appliances via individual fused circuits. Keeps everything safe and organised.
Watch Bex explain her 12V system in under 60 seconds — search "Bex Rae Hart 12V van setup" on YouTube, or go directly to youtube.com/@BexRaeHart/shorts
Here is everything you need for a complete beginner 12V lithium system. I've listed recommended products where relevant — these are what I'd buy if I were starting from scratch today.
LiFePO4 is the only chemistry worth considering for a van build. It's safe (no thermal runaway risk), lasts 2,000–4,000+ cycles, and you can use 80–90% of rated capacity. A 100Ah LiFePO4 battery gives you roughly 1,200Wh of usable power. Good brands: Fogstar Drift, Renogy, Battle Born, Victron Smart Lithium. Budget: the Fogstar Drift 100Ah is outstanding value at around £200–250.
The Victron SmartSolar MPPT range is the gold standard. The 75/15 handles up to 220W of solar (12V battery), the 100/20 handles up to 290W. Both have built-in Bluetooth so you can monitor them live from your phone via the VictronConnect app. Budget alternative: Renogy Wanderer. But Victron's lifetime and reliability make it worth the extra.
Rigid panels (monocrystalline) are more efficient and last 25+ years — best if you have a roof rack or can mount them elevated. Flexible panels stick flat to the roof with adhesive — lighter, no rack needed, slightly less efficient. For a beginner 100Ah system, a single 200W rigid panel is the sweet spot. Good budget brand: Renogy. If you want more later, adding a second panel is straightforward.
Charges your leisure battery from your van's alternator while driving. The Victron Orion-Tr Smart is the best option — it's specifically designed for LiFePO4 batteries and has Bluetooth monitoring. The 30A version charges at up to 360W. Do not use a simple split charge relay with lithium batteries — it cannot provide the correct charging profile and risks alternator damage. Budget: around £130–160.
Distributes 12V power to all your circuits. Look for a box with individual fused slots — one per appliance or circuit. A 12-way blade fuse box with a built-in bus bar is ideal. You'll want separate circuits for fridge, lighting, fan, USB charging, inverter, etc. Budget: £15–40 for a quality fuse box.
A battery monitor tells you exactly how much charge is left in your battery — not just a rough voltage reading, but accurate state of charge as a percentage. The Victron SmartShunt is the modern version — no display, but connects via Bluetooth to your phone. The BMV-712 has a physical display on the wall. Both are excellent. Don't skip this — guessing your battery state is how people damage batteries.
You'll need: 50mm² welding cable for battery to fuse box main run, 16–25mm² cable for DC-DC charger and MPPT connections, 2.5–6mm² cable for appliance circuits. Buy ANL fuses or MIDI fuses for your main battery protection (100–200A). Use MC4 connectors for solar panel connections. Buy a proper crimping tool — poor connections cause fires.
Buy the Victron components (MPPT, DC-DC charger, battery monitor) even on a tight budget — they will outlast your van. Save money on the battery brand instead; Fogstar Drift and Renogy offer excellent LiFePO4 chemistry at lower prices than Victron's own battery.
This is the part most beginners find intimidating. The good news: if you follow this order carefully, it's a logical process. Always work on one connection at a time and double-check polarity (positive/negative) before connecting anything to the battery.
Always fuse as close to the battery positive terminal as possible. Your main ANL or MIDI fuse should be within 30cm of the battery. This protects against short circuit — an unfused cable can carry hundreds of amps and start a fire in seconds. Never skip this step.
A bus bar (positive and negative) gives you a clean central point to connect multiple wires rather than cramming everything onto the battery terminals. It makes the system neater, easier to fault-find, and more expandable. Buy a pair of bus bars with covers — around £10–20 — and your wiring will thank you.
Battery mounted → ANL fuse holder fitted (fuse out) → MPPT connected to battery → Solar panels connected to MPPT → ANL fuse in → DC-DC charger wired → Fuse box connected → Appliances wired in → SmartShunt installed → VictronConnect app configured. Done.
The most common question after building a 12V system is: how long will everything last? Here's a realistic look at typical van life power consumption and how a 100Ah LiFePO4 battery handles it.
| Appliance | Typical Draw | Hours/Day | Wh/Day |
|---|---|---|---|
| 12V Compressor Fridge e.g. Dometic CFX3 35, Iceco |
45W avg | 24h cycling | ~45Wh compressor runs ~30% duty cycle |
| Phone Charging | 10–18W | 2h | 20Wh |
| Laptop (Mac/PC) | 45W | 4h | 180Wh |
| LED Van Lighting | 10W | 5h | 50Wh |
| 12V Fan (e.g. Maxxair vent) | 20W avg | 8h | 160Wh |
| Camera Battery Charger | 15W | 2h | 30Wh |
| Diesel Heater (fan) | 15W avg | 8h night | 120Wh |
| USB Hub / misc | 10W | 4h | 40Wh |
A 100Ah LiFePO4 battery stores approximately 1,200Wh of usable energy (assuming 80% usable depth of discharge, which is conservative — many LiFePO4 batteries safely go to 90%).
At ~455Wh per day (the example above), that's 2.5 days of power with no solar input at all. In good European sunshine, a single 200W panel produces 800–1,000Wh per day — more than covering this daily load and keeping the battery topped up.
Size your battery for 2–3 days of your daily usage with no charging. For 455Wh/day that means a minimum 100Ah LiFePO4 (which gives exactly this). If you're a heavy user (laptop + diesel heater + fridge = 700Wh+), move to a 150–200Ah battery.
You don't have to use Victron. There are cheaper alternatives for every component. But after two-plus years living in Sioux, I use Victron for everything — and here's the honest reason why.
Victron is a Dutch company that has been making marine and off-grid electrical equipment since 1975. Their products are used on superyachts, in off-grid cabins, and in professional vehicle conversions worldwide. They are not the cheapest option — but they are the most reliable, the best monitored, and the ones that will still work perfectly in a decade when cheaper alternatives have failed.
More importantly for van life: everything connects together. The MPPT talks to the Orion-Tr which talks to the SmartShunt — and you see it all in one place in the free VictronConnect app on your phone. When something isn't right, you can see exactly why.
Extracts maximum power from your solar panels and charges the battery correctly. The "Smart" prefix means built-in Bluetooth — open the VictronConnect app and see exactly how many watts are coming in, the battery voltage, and daily/weekly solar yield history. Set it up once and it works perfectly for years.
Charges your leisure battery from the alternator while you drive. Critically, it uses a proper LiFePO4 charging algorithm — not just a simple relay. The Smart version detects the alternator automatically (no ignition wire needed on many vans) and manages the charge rate intelligently. Protects your alternator from the high initial charge demand that raw lithium batteries can cause.
The most important piece of monitoring kit in the van. The SmartShunt measures every amp going in and out of your battery and calculates your true state of charge as a percentage — accurate to within 1–2%. You'll always know exactly how much power you have left. The BMV-712 adds a physical display; the SmartShunt uses Bluetooth to your phone only.
One app shows everything: live solar input, battery percentage, DC-DC charger status, historical data, and alerts. You can configure every setting on your MPPT, Orion-Tr, and SmartShunt via Bluetooth without needing a laptop or any special tools. It just works. Genuinely one of the best bits of software in van life.
I had a cheaper MPPT on Sioux first. It worked — until it didn't. The Victron replacement has been running for eighteen months with zero issues and I can see exactly what it's doing from my bunk. That peace of mind is worth the extra money every single time.
— Bex Rae Hart, living in Sioux full-timeRenogy, EPEVER, and Srne make solid MPPT controllers at lower prices. Renogy DC-DC chargers are also well regarded. If your budget is very tight, start with Renogy kit and upgrade to Victron when you can — the wiring stays the same, you just swap the components. The most important thing is that you have a proper system, not that every component is premium.
Every mistake in this section is one I've either made myself, seen in someone else's van, or been asked about by beginners who realised too late. Learn from all of us.
AGM (absorbed glass mat lead acid) batteries are cheaper upfront — but you can only safely use 50% of their rated capacity without damaging them. A 100Ah AGM gives you 50Ah usable. A 100Ah LiFePO4 gives you 80–90Ah. They're also twice as heavy and last only 400–600 cycles vs 2,000+ for lithium. The "cheap" battery often costs more long-term.
If your main ANL fuse is 1 metre from the battery with unfused cable in between, that cable is unprotected. A short circuit in that cable can cause hundreds of amps to flow and start a fire within seconds. The fuse must be within 30cm of the battery positive terminal — this is not optional.
Incorrectly fused electrical systems are the leading cause of vehicle fires in van conversions. Fuse every circuit. Fuse close to the source. Use the correct cable cross-section for the current it carries. When in doubt, go heavier on cable and smaller on fuse rating.
Thin cable has higher resistance. High resistance means voltage drop — your fridge gets 11.5V instead of 12.6V and works harder to compensate. It also means the cable heats up, which is a fire risk at high current draws. Use the correct cable size for the current and the run length. For anything over 10A and more than 2 metres, go up a cable size.
A split charge relay (VSR — voltage sensitive relay) simply connects your starter and leisure batteries together when voltage is high enough. This is fine for AGM — but with a lithium battery, when it's at low charge it will draw the maximum current from the alternator with no limitation. Modern van alternators are not designed for this and can fail prematurely. Always use a proper DC-DC (B2B) charger with lithium.
Running a lithium battery repeatedly down to 0% damages it over time — the BMS will cut out to protect it, but sustained deep discharge shortens battery life. A battery monitor (SmartShunt or BMV-712) lets you keep the battery in its ideal operating range of 20–90% state of charge for maximum longevity. Don't guess — measure.
A 1000W inverter connected to a 100Ah battery can theoretically run a kettle — for about 6 minutes before flattening the battery. High-draw mains appliances (hair dryer, kettle, microwave) are genuinely impractical for off-grid van life at 100Ah. Switch to gas for cooking and a 12V travel kettle. Save the inverter for laptop charging and camera batteries.
Before you power up your new 12V system for the first time, run through this checklist:
If all eight boxes are ticked, your system is correctly installed. Watch the MPPT in the VictronConnect app — you should see solar watts arriving within minutes of pointing the panels at the sky. Congratulations: you now have a proper van life power system.
Bex breaks down her exact 12V setup in her YouTube Shorts series — the quick, visual way to see how everything connects in a real van. No jargon, no hour-long lectures.
Watch the 12V Short on YouTube →