Van Life Battery Guide UK 2026: LiFePO4 vs AGM, Sizing, Charging & Real Costs
Your battery bank is the heart of a campervan electrical system. Everything depends on it — the fridge, the lights, the water pump, the phone charger, the laptop for evening work. Get the battery right and everything else falls into place. Get it wrong and you are hunting for hook-up points every other day.
I have run three different battery setups in my van over the last two years: a £250 AGM, a £500 "budget" LiFePO4 from eBay, and a £950 Victron Smart Lithium system. The difference between them is not just capacity — it is how they behave in UK winter, how they handle partial charging, and whether you actually get the capacity you paid for.
This guide covers what UK van lifers actually need to know: real prices, UK-specific winter performance, practical sizing for common vans, and which batteries to actually buy in 2026.
LiFePO4 vs AGM: The UK Van Life Verdict
For most UK van builds in 2026, LiFePO4 (lithium iron phosphate) wins. The price has dropped enough that the old argument "AGM is cheaper" no longer holds at a total-cost-of-ownership level. But there are edge cases where AGM still makes sense.
When AGM Is the Right Choice
AGM batteries cost £100–300 for a solid 100Ah unit. They are available at Halfords, Euro Car Parts, and any motor factor across the UK. If your van is a weekend-only summer vehicle with minimal electrical load (LED lights, phone charging, occasional water pump), an AGM is fine. Replace it every 3–4 years and you have spent less overall.
AGM also handles cold better than early lithium chemistries. A 100Ah AGM at 0°C still delivers ~80Ah usable (within the 50% DoD limit). Old LiFePO4 cells could not charge below 0°C at all — modern units with internal heating have solved this, but it adds cost.
When LiFePO4 Is the Right Choice
For anything beyond weekend use — full-time living, winter trips, running a 12V fridge compressor overnight, any inverter use — LiFePO4 is worth the premium. Here is why:
Usable capacity: A 100Ah AGM gives you 50Ah usable (to keep cycle life reasonable). A 100Ah LiFePO4 gives you 80–90Ah. You effectively double your usable capacity for the same physical footprint.
Weight: A 100Ah AGM weighs ~26kg. A 100Ah LiFePO4 weighs ~12kg. In a van where payload matters, that 14kg saving is noticeable.
Cycle life: AGM lasts 500–800 cycles (roughly 3–5 years of van life). LiFePO4 lasts 2,000–5,000 cycles (8–15 years). You will probably replace the van before the battery.
Charging speed: LiFePO4 accepts charge much faster than AGM. A 50A alternator charger can fill a 100Ah LiFePO4 from 20% to 80% in about 1.5 hours. AGM takes 3–4 hours for the same top-up because internal resistance limits the charge rate.
The Bottom Line
| Factor | AGM 100Ah | LiFePO4 100Ah |
|---|---|---|
| Upfront cost | £150–250 | £350–950 |
| Usable capacity | 50Ah | 80–90Ah |
| Weight | 26kg | 12kg |
| Cycle life | 500–800 | 2,000–5,000 |
| Charge speed | Slow | Fast |
| UK winter performance | Good (derates but works) | Requires heating below 0°C |
| Fits under a seat | Tight | Yes |
| Total cost over 10 years | £450–750 (3 replacements) | £350–950 (1 purchase) |
How to Size Your Battery Bank
The most common mistake in UK van builds is undersizing the battery. Builders calculate summer consumption, then discover the 100Ah battery barely lasts one overcast winter day.
Step 1: Calculate Your Daily Consumption
| Device | Typical Draw | Hours/Day | Wh/Day |
|---|---|---|---|
| LED lights (4x) | 8W total | 5 | 40 |
| 12V fridge compressor | 5A avg (40% duty cycle) | 24 (9.6h runtime) | 480 |
| Laptop charging | 60W | 3 | 180 |
| Phone charging (2x) | 10W each | 3 | 60 |
| Water pump | 5A | 0.5 | 30 |
| Diesel heater fan | 2A avg | 8 (winter) | 180 |
| Vent fan | 1A | 6 | 72 |
| Total daily | 1,042Wh |
Step 2: Account for Efficiency Losses
Multiply by 1.25 for inverter losses, wiring losses, and ageing. 1,042 x 1.25 = 1,302Wh.
Step 3: Choose Your Depth of Discharge
AGM: 50% DoD (usable capacity = half of rated Ah) LiFePO4: 80% DoD (usable capacity = 80% of rated Ah)
Step 4: Calculate Required Ah
Required Ah = Daily Wh / (12V x DoD)
- AGM: 1,302 / (12 x 0.5) = 217Ah → get a 220Ah or 2x 110Ah
- LiFePO4: 1,302 / (12 x 0.8) = 135Ah → get a 150Ah or a single 200Ah for headroom
UK Winter Adjustment
In December and January, solar production drops to 20–30% of summer levels. If you rely partly on solar, add 50% to your battery capacity: a 200Ah LiFePO4 for the example above (135 x 1.5 = 202Ah).
Best UK Battery Options 2026
Budget (Under £350)
- Fogstar LiFePO4 105Ah — £299. Solid entry-level lithium, Bluetooth BMS, can charge at -20°C (internal heating). Popular in the UK van community. 10kg.
- Renogy 100Ah LiFePO4 — £339. Self-heating, good BMS, reliable brand. 11kg.
- Varta LA95 AGM — £189. 95Ah, 26kg. The best AGM option for budget builds. Available at Halfords and Euro Car Parts.
Mid-Range (£350–£600)
- PowerQueen LiFePO4 100Ah — £379. Low-temp protection, Bluetooth, compact. 10kg.
- Eco-Worthy LiFePO4 200Ah — £579. Good value for the capacity. 21kg. No low-temp charging — needs to be in heated space.
- Victron Smart Lithium 100Ah — £559. Bluetooth monitoring, excellent BMS, integrates with Victron ecosystem. 11kg.
Premium (Over £600)
- Victron Smart Lithium 200Ah — £949. The gold standard. Internal heater, Bluetooth, 12.8V nominal, integrates with Victron MPPT and inverter. 20kg.
- Battle Born 100Ah GC3 — £999 (import from US). 10-year warranty, exceptional build quality. Harder to get in the UK now. 13kg.
Where to Buy
- Fogstar (fogstar.co.uk) — best prices for lithium in the UK, fast shipping
- Bimble Solar (bimblesolar.com) — good range of lithium and AGM, technical support
- Alpha Batteries (alpha-batteries.co.uk) — AGM specialist, trade counter in London
- Halfords — AGM only, but good for emergency replacements
- Amazon UK — good for Renogy and Eco-Worthy, check seller reviews
Charging Your Battery
Solar Charging
Solar is the primary charging source for most off-grid van lifers. For UK conditions:
- MPPT controller: Mandatory for lithium. PWM loses 20–30% of available power. Victron SmartSolar MPPT is the standard choice. A 30A unit (£150) handles up to 440W of solar at 12V.
- Panel sizing: 200W minimum for a 100Ah lithium battery. 400W for comfortable year-round use. In December, a 200W panel array on a clear day produces about 600Wh — about half your daily need.
- Wiring: 4mm² solar cable for runs under 5m. 6mm² for longer runs. Use MC4 connectors, not cheap choc blocks.
Alternator Charging
When solar falls short (which it will in UK winter), the alternator fills the gap.
- Standard split-charge relay: Works for AGM but not for LiFePO4. Lithium's low internal resistance can draw 100A+ from the alternator, overheating it.
- DC-DC charger: Required for lithium. The Victron Orion-TR Smart 12/12-30 (£180) is the standard. It limits charge current to 30A, protects the alternator, and applies the correct lithium charging profile.
- Wiring: 10mm² cable from starter battery to DC-DC charger. Fuse at both ends (50A on starter side, 40A on leisure side).
Charging Profiles
| Battery Type | Absorption Voltage | Float Voltage | Notes |
|---|---|---|---|
| AGM | 14.4–14.7V | 13.5–13.8V | Lower float to prevent water loss |
| Gel | 14.1–14.4V | 13.5–13.8V | Lower voltage than AGM |
| LiFePO4 | 14.2–14.6V | 13.4–13.6V | No absorption phase needed (BMS handles it) |
Installing Your Battery
Location
The battery must be in a dry, ventilated space. Common locations:
- Under a passenger seat (most common in Transit Custom, Sprinter, Ducato)
- Under the driver seat (if space allows)
- In a seat base box
- Under a bench seat
Lithium batteries should not be in an unheated locker that drops below 0°C. If they are, use a battery with internal heating (Fogstar, Renogy self-heating, Victron with heater) or add a 12V heater pad (£15).
Wiring
- Battery cable: 16mm² for runs under 2m (covers most van installations up to 250A). 25mm² for longer runs or higher loads.
- Main fuse: Install within 30cm of the battery positive terminal. 150A for a 100Ah battery with 2000W inverter. 250A for larger systems.
- Bus bars: Use a quality bus bar (Victron Lynx, Blue Sea Systems) for distributing loads. Avoid screw-terminal choc blocks — they loosen with vibration.
- Crimp vs solder: Crimp only for van wiring. Solder joints can fail under vibration. Use a decent hydraulic crimper (the £40 ones from Amazon are fine).
Battery Monitoring
You cannot manage what you cannot measure. A battery monitor is essential for any van electrical system.
- Victron BMV-712 (£150) — the standard. Bluetooth, shunt-based, accurate to 1%. Shows voltage, current, state of charge, and historical data.
- Victron SmartShunt (£100) — same as BMV-712 but without the display (smartphone only). Slightly cheaper.
- Renogy BT-2 (£35) — cheap Bluetooth monitor. Less accurate but better than nothing.
Set the low-voltage alarm to:
- AGM: 11.8V (under load)
- LiFePO4: 11.5V (under load) — or 12.0V to be conservative
UK Winter Performance
Here is what actually happens to a campervan battery in a British winter:
A 200Ah LiFePO4 battery charged to 100% by solar in September. By late November, with short days and frequent overcast, the solar is producing 200–400Wh/day. The fridge draws ~500Wh/day. The battery discharges 2–3% per day even without loads due to the BMS draw and inverter standby. By mid-December, the battery is at 40% and has not seen a full charge in 3 weeks.
The fix: drive the van for 1–2 hours every 7–10 days, using the DC-DC charger to top up. A 30A DC-DC charger running for 1.5 hours puts about 400Wh back in — enough to cover the deficit.
If you cannot drive regularly (winter parking, city living, no movement), you need either more solar (400W+), a generator, or a hook-up every 2–3 weeks.
Safety
- Fuse everything: Battery positive, solar input, alternator input, inverter input, each load circuit. Every fuse within 30cm of its power source.
- Use the right fuse type: MEGA or ANL for battery main fuse (handles high interrupt current). Blade fuses for load circuits. Do not use glass fuses in a van.
- Ventilation: LiFePO4 is safer than lead-acid (no hydrogen gas), but if a cell fails catastrophically it can vent. A battery box with a vent to outside is best practice.
- Fire extinguisher: Keep a 2kg ABC extinguisher accessible. Not in a locked cupboard. Not behind the driver seat. Mount it where the driver can reach it from the cab.
- Don't mix chemistries: Never connect an AGM and LiFePO4 together in the same bank. They charge at different voltages.
FAQ
Q: Can I charge LiFePO4 below freezing? A: Standard LiFePO4 cells cannot accept charge below 0°C — it damages the anode. Batteries with internal heating (Fogstar, Renogy self-heating) can heat themselves before charging. Alternatively, mount the battery in the van's heated interior.
Q: How long does a 100Ah battery run a 12V fridge? A: A typical 12V compressor fridge (Vitrifrigo, Dometic, Waeco) draws about 5A at 40% duty cycle = 48Ah per day. A 100Ah LiFePO4 (80Ah usable) runs the fridge for 1.5 days with nothing else. A 100Ah AGM (50Ah usable) runs it for about 1 day.
Q: Can I use car starter batteries for leisure? A: No. Starter batteries are designed for high current bursts (starting the engine) not deep cycling. They will fail within months if regularly discharged below 80%.
Q: Do I need a BMS (Battery Management System) in my LiFePO4 battery? A: All quality LiFePO4 batteries have a built-in BMS. It protects against over-voltage, under-voltage, over-current, over-temperature, and cell imbalance. Do not buy a battery without a BMS.
Q: What size cable from alternator to battery? A: For a 30A DC-DC charger, use 10mm² cable. For 50A, use 16mm². Fuse at both ends within 30cm of each battery terminal.
Q: Can I add more batteries later? A: With lithium, yes — if they are the same model and state of charge. Connect in parallel. Each battery needs its own fuse. AGM is harder — mixing old and new AGM batteries causes the older one to drag down the newer one.
Q: What is the best battery for a VW Transporter T6? A: The T6 has a tight under-seat space. Maximum height is 200mm. The Fogstar 105Ah (180mm) and Victron 100Ah (190mm) both fit. For AGM, the Varta LA95 fits in the standard battery tray.
