How Long Will My Campervan Battery Last? (Real-World Data)
"How long will my battery last?" is the single most common question in the UK campervan community. The answer depends on your battery size, battery type, and what you are running — but we can give you real numbers based on actual usage data from UK van builds. This guide cuts through the theory and shows you what to genuinely expect. For a complete overview of battery types and sizing, see our campervan battery guide.
The short answer: a typical 200Ah LiFePO4 battery will power a well-equipped campervan for 1-3 days without any charging input, depending on usage. But "typical" covers a wide range of scenarios, so let us break it down with real numbers. If you want a personalised answer, our calculator will tell you exactly how long your specific battery will last based on the appliances you actually use.
Get your exact battery run time
Enter your appliances and our free calculator tells you exactly how many hours your battery will last — and what size you need for off-grid stays.
Understanding Battery Capacity
Before looking at run times, you need to understand usable capacity, because the number on the battery label is not the number you actually get.
LiFePO4 (Lithium)
A LiFePO4 battery can be safely discharged to 20% state of charge, giving you roughly 80% usable capacity. Some manufacturers say 90-95% is safe, but 80% is the practical recommendation for maximum lifespan.
- 100Ah LiFePO4 = ~80Ah usable = ~1,024Wh usable
- 200Ah LiFePO4 = ~160Ah usable = ~2,048Wh usable
- 300Ah LiFePO4 = ~240Ah usable = ~3,072Wh usable
AGM (Lead-Acid)
AGM batteries should not be discharged below 50% state of charge to maintain reasonable cycle life. This gives you 50% usable capacity.
- 100Ah AGM = ~50Ah usable = ~600Wh usable
- 200Ah AGM = ~100Ah usable = ~1,200Wh usable
The difference is dramatic. A 200Ah LiFePO4 provides more usable energy than two 200Ah AGM batteries combined.
Real-World Power Consumption
Here are measured power consumption figures for common campervan appliances in UK builds:
| Appliance | Typical Power Draw | Daily Usage | Daily Energy |
|---|---|---|---|
| LED lighting (6 lights) | 18W | 5 hours | 90Wh |
| Compressor fridge (Dometic CFX 50) | 45W average | 24 hours (cycling) | 360Wh (actual ~30-40Wh/hr when running) |
| Diesel heater (Eberspacher/Webasto) | 10-30W (fan + glow plug) | 10 hours overnight | 150-200Wh |
| Phone charging (x2) | 15W | 3 hours | 45Wh |
| Laptop charging | 65W | 3 hours | 195Wh |
| Water pump | 60W | 10 minutes total | 10Wh |
| USB sockets (various devices) | 10W | 5 hours | 50Wh |
| Inverter standby | 10-15W | 24 hours | 240-360Wh |
| Roof fan (MaxxAir) | 30W | 4 hours (summer) | 120Wh |
Inverter standby is a hidden drain
If you leave your inverter switched on 24/7, it draws 10-15W even with nothing plugged in. That is 240-360Wh per day — more than your fridge. Switch the inverter off when not in use, or get an inverter with a low-power standby mode.
Scenario 1: Weekend Trip — Light Use
Setup: 200Ah LiFePO4, no solar, no driving (worst case).
Daily usage:
- LED lighting: 90Wh
- Compressor fridge: 360Wh
- Phone charging: 45Wh
- Water pump: 10Wh
- USB sockets: 30Wh
Total daily draw: ~535Wh (approx 42Ah at 12.8V)
With 160Ah usable (200Ah at 80% depth), this battery lasts approximately 3.8 days (91 hours) without any charging input.
In reality, you would drive to and from your destination, gaining charge from the DC-DC charger, plus any solar. A weekend trip is comfortably covered.
Scenario 2: Week-Long Holiday — Moderate Use
Setup: 200Ah LiFePO4, 200W solar, occasional driving.
Daily usage:
- LED lighting: 90Wh
- Compressor fridge: 360Wh
- Diesel heater (winter): 180Wh
- Phone charging: 45Wh
- Laptop: 195Wh
- Water pump: 10Wh
- Inverter standby (4 hours): 60Wh
Total daily draw: ~940Wh (approx 73Ah at 12.8V)
Without any charging, 160Ah usable lasts approximately 2.2 days (52 hours).
With 200W of solar in summer (averaging 3-4 peak sun hours in the UK, generating 600-800Wh per day), you replenish roughly 65-85% of daily usage. This means the battery slowly depletes — you can extend to 5-7 days off-grid in summer before needing a full charge from driving or shore power.
In winter with limited solar (1-2 peak sun hours, generating 200-400Wh), the solar covers only 20-40% of usage. You will need to drive or plug in every 2-3 days.
Scenario 3: Full-Time Van Life — Heavy Use
Setup: 400Ah LiFePO4 (2x 200Ah in parallel), 400W solar, daily driving or regular shore power.
Daily usage:
- LED lighting: 90Wh
- Compressor fridge: 360Wh
- Diesel heater (winter): 180Wh
- Phone and tablet charging: 60Wh
- Laptop (remote work): 390Wh (6 hours)
- Water pump: 20Wh
- Inverter standby: 120Wh
- Occasional 230V appliance (hair dryer, blender): 100Wh average
- Starlink or mobile router: 80Wh
Total daily draw: ~1,400Wh (approx 109Ah at 12.8V)
With 320Ah usable (400Ah at 80% depth), the battery lasts approximately 2.9 days (70 hours) without charging.
With 400W of solar in UK summer (generating 1,200-1,600Wh), solar alone can cover daily usage. In winter, you need supplementary charging from the alternator or shore power at least every other day.
Scenario 4: Minimal Setup — Budget Build
Setup: 100Ah AGM, no solar, occasional driving.
Daily usage:
- LED lighting: 60Wh
- Compressor fridge: 360Wh
- Phone charging: 30Wh
- Water pump: 10Wh
Total daily draw: ~460Wh (approx 38Ah at 12V)
With 50Ah usable (100Ah AGM at 50% depth), this battery lasts approximately 1.3 days (31 hours).
This is tight. You are looking at needing a charge every day, which means driving or shore power daily. This is why we generally recommend LiFePO4 — even a 100Ah lithium (with 80Ah usable) gives you over twice the run time of a 100Ah AGM.
Factors That Affect Battery Life
Temperature
Cold weather reduces battery capacity temporarily. At 0°C, expect about 10-15% less usable capacity from LiFePO4. In a UK winter campervan, this means your 200Ah battery effectively behaves like a 170-180Ah battery in cold conditions.
Battery Age
LiFePO4 batteries maintain close to their rated capacity for the first 2,000+ cycles, then gradually decline. A 5-year-old battery with regular use might have 85-90% of its original capacity. AGM batteries degrade faster, losing capacity noticeably after 200-300 cycles.
Inverter Efficiency
When running 230V appliances through an inverter, you lose 10-15% of energy to conversion. A 100W appliance actually draws about 115W from the battery when running through an inverter. Factor this into your calculations.
Beware of manufacturer claims
Some battery brands advertise run times based on 100% depth of discharge (draining the battery completely). This is not realistic for regular use — it dramatically shortens battery lifespan. Always calculate based on 80% depth for LiFePO4 and 50% for AGM.
Parasitic Draws
Many devices draw small amounts of power even when "off." Common culprits in campervans:
- Inverter on standby: 10-15W
- DC-DC charger standby: 1-3W
- MPPT controller: 1-2W
- Bluetooth battery monitor: 0.1W
- LED controller in standby: 1-2W
- Diesel heater controller: 1-3W
Collectively, these can add up to 15-25W of constant drain, which is 360-600Wh per day — a significant amount on a small system. Use isolator switches to disconnect devices you are not using.
How Long Will My Battery Last in Years?
Beyond the single-charge run time, people also ask about the total lifespan of their battery:
LiFePO4
- Cycle life: 3,000-5,000 cycles at 80% depth of discharge
- Calendar life: 10-15 years
- Practical UK campervan life: 8-12+ years for most users
If you cycle your battery once per day, 3,000 cycles gives you over 8 years. Most campervan owners do not cycle daily (the battery is often partially charged by solar during the day), so real-world lifespan is typically 10+ years.
AGM
- Cycle life: 300-500 cycles at 50% depth of discharge
- Calendar life: 5-7 years
- Practical UK campervan life: 2-4 years for regular users
AGM batteries degrade noticeably after 2-3 years of regular use. Budget-friendly but replacement costs add up.
Tips to Make Your Battery Last Longer (Per Charge)
- Switch off the inverter when not in use. This alone can save 200-350Wh per day.
- Use 12V appliances where possible. A 12V fridge is more efficient than a 230V fridge through an inverter.
- LED lighting only. LEDs draw a fraction of the power of halogen or incandescent bulbs.
- Thermostat your diesel heater. Running it on full blast all night uses 2-3 times more energy than a thermostatically controlled cycle.
- Charge opportunistically. Even a short drive recharges through the DC-DC charger. A 30-minute drive with a 30A DC-DC adds about 15Ah.
- Monitor your usage. A battery monitor (like the Victron SmartShunt) shows exactly where your energy goes and helps you identify wasteful draws.
Use our calculator to model your specific appliances and get a precise run time estimate for your battery configuration.
FAQ
How long will a 200Ah lithium battery run a fridge?
A typical compressor fridge draws 360-500Wh per day (it cycles on and off). A 200Ah LiFePO4 battery (160Ah usable, 2,048Wh) will run a fridge alone for approximately 4-5 days without any charging input.
Can I run a diesel heater all night on a 100Ah battery?
A diesel heater draws 10-30W depending on the setting. Running it for 10 hours overnight uses 100-300Wh. A 100Ah LiFePO4 battery (80Ah usable, 1,024Wh) can handle this for 3-10 nights depending on heater settings — but remember you are also running other appliances.
How long does a campervan battery take to charge?
From a DC-DC charger (30A), a 200Ah LiFePO4 battery charges from 20% to 100% in approximately 5-6 hours. From 200W of solar in UK summer conditions, expect 4-6 hours for a full charge. From shore power (20A charger), expect 8-10 hours.
Do I need two batteries for full-time van life?
Not necessarily. A single 230Ah LiFePO4 (like the Fogstar Drift 230Ah) provides enough capacity for many full-time van lifers. If you work remotely and use a lot of power, or want extended off-grid capability, two batteries in parallel (400-460Ah) give you more comfortable margins.