How many days can your motorhome go without electric hook-up?
Answer four simple questions to find out how many nights you can spend off-grid. Campervans too.
Step 1 of 4: your trip
When are you travelling?
And what’s the weather forecast?
Why the season matters
In summer, the sun recharges the battery but the fridge works harder. In winter, the heating runs, the evenings are long, the panel produces little and the cold reduces battery capacity.
Travelling with a caravan? Calculate a caravan’s autonomy
In short
A standard motorhome (95 Ah AGM battery, 100 Wp panel, fridge on gas) lasts about 6 days without hook-up in summer in changeable weather, and often much longer in sunny weather. In winter, with the heating on, expect barely a day. The biggest loads are a compressor fridge, e-bikes and the heating.
How we calculate
We add up what your appliances use in a day, in watt-hours (Wh), according to the season: heating only counts in spring, autumn and winter, a compressor fridge uses more when it is hot, and lighting more when the evenings are long. Standby loads (control panel, gas detector) are always included. 230 V appliances add the inverter’s losses and its no-load consumption.
A battery is never fully drained. We count half the capacity of a lead-acid battery (AGM or gel), to avoid damaging it, and 80 to 90% of a lithium battery. Cold weather takes 10 to 20% off a lead-acid battery.
Charging comes from the solar panel and, if you drive, from the alternator. For the panel: its power in Wp × the season’s peak sun hours × 55 to 70% efficiency for a panel mounted flat on the roof. Peak sun hours are averages for France, from the north to the Mediterranean, taken from the European Commission’s PVGIS database and adjusted for the weather you choose.
The result is a range: the low end for a power-hungry, cloudy day, the high end for a frugal, bright one. Beyond 14 days, it is no longer the battery that stops you, but fresh water, waste water or gas.
Days without hook-up = usable battery energy ÷ (daily consumption − daily charging)
Appliance consumption, in Wh per day
The values used by the tool, taken from manufacturers’ data sheets (Dometic, Thetford, Truma, Alde, Webasto, Fiamma, ResMed…) for typical use, from the most frugal to the most power-hungry.
| Appliance | Summer | Spring, autumn | Winter |
|---|---|---|---|
| Compressor fridge (Dometic, Thetford…) | 350 – 600 | 230 – 400 | 150 – 280 |
| Absorption fridge, on gas when parked | 5 – 20 | 5 – 20 | 5 – 20 |
| Gas heating (Truma Combi, Alde) | 0 – 20 | 40 – 120 | 120 – 300 |
| Diesel heating (Truma Combi D, Webasto…) | 0 – 20 | 50 – 150 | 150 – 400 |
| LED lighting | 30 – 80 | 50 – 120 | 80 – 160 |
| Water pump | 15 – 40 | 12 – 35 | 10 – 30 |
| Roof vent fan (MaxxFan, Turbo-Vent) | 40 – 200 | 10 – 60 | 0 – 15 |
| 12 V TV and receiver | 50 – 150 | 60 – 170 | 80 – 200 |
| Phone or tabletper device | 10 – 25 | 10 – 25 | 10 – 25 |
| Laptopper laptop | 40 – 120 | 40 – 120 | 40 – 120 |
| E-bike to chargeper bike | 250 – 600 | 250 – 600 | 250 – 600 |
| Kettle, via an inverter | 100 – 250 | 100 – 250 | 100 – 250 |
| Capsule coffee machine, via an inverter | 40 – 120 | 40 – 120 | 40 – 120 |
| Hairdryer, via an inverter | 80 – 200 | 80 – 200 | 80 – 200 |
| CPAP machine (sleep apnoea), without humidifier | 40 – 120 | 40 – 120 | 40 – 120 |
| Standby loads (control panel, gas detector) | 20 – 60 | ||
| Inverter switched on | 30 – 120 | ||
230 V appliances: energy drawn at the socket. The tool adds 8 to 15% for inverter losses.
Three example motorhomes and campervans
Standard motorhome, in summer
95 Ah AGM battery, 100 Wp panel, fridge on gas, heating off, lighting, water pump, roof fan, TV and two phones, changeable weather.
About 6 days
At least 1.5 days in the worst case
Converted campervan and two e-bikes
200 Ah lithium battery, 200 Wp, battery-to-battery charger and 1 hour of driving a day, compressor fridge, roof fan, laptop, two phones and two e-bikes to charge, in spring.
About 2.5 days
Between 1 day and 9 days, depending on the weather and your usage
In winter, diesel heating
Two 95 Ah AGM batteries, 150 Wp, diesel heating, fridge on gas, lighting, water pump, TV and two phones, grey skies.
About 1.5 days
Between 1 day and 2.5 days, depending on the weather and your usage
6 A, 10 A or 16 A: which campsite hook-up?
A 6 A hook-up (as on many French campsites) gives 1,380 W: enough to charge the battery and run the fridge and lighting, but not an electric heater. A 10 A hook-up (2,300 W) also allows a small fan heater or a kettle, but not both at once. A 16 A hook-up (3,680 W) lets the kettle, hairdryer and heating run without tripping the breaker.
When the campsite provides it, the amperage is shown on its page in the Campernest directory. Bring a 25 m cable and an adaptor for the blue European socket.
Frequently asked questions
How many days can a motorhome go off-grid?
A standard motorhome, with a 95 Ah AGM battery, a 100 Wp panel and a fridge on gas, lasts about 6 days in summer in changeable weather, and often more than two weeks in sunshine. In winter, with the heating on, expect barely a day.
How long will a motorhome leisure battery last?
A 95 Ah AGM battery gives about 550 Wh of usable energy, as it should only be run down to half. A motorhome uses 300 to 500 Wh a day in summer: with no panel and no driving, the battery lasts 1 to 2 days.
What size solar panel do I need on a motorhome?
A factory-fitted 100 to 150 Wp is enough in summer with a fridge on gas. With a compressor fridge, e-bikes, or in spring and autumn, aim for 200 to 300 Wp. A 100 Wp panel mounted flat produces 275 to 520 Wh a day in summer sunshine.
Does a motorhome charge the leisure battery while driving?
Yes, through the split-charge relay. With the “smart” alternators of Euro 6 engines, only 60 to 190 Wh goes in per hour of driving. A 20 to 30 A battery-to-battery charger (DC-DC) delivers 230 to 380: one hour of driving then covers a day of compressor fridge use.
Can I charge e-bikes without hook-up?
A 500 Wh e-bike battery takes 550 to 700 Wh from the leisure battery, including inverter losses: a whole 95 Ah AGM. You need a lithium battery of at least 200 Ah and 200 to 300 Wp, or a night on hook-up.
Can I use a kettle, coffee machine or hairdryer off-grid?
Yes, with a 1,500 to 2,000 W inverter and preferably a lithium battery. A one-litre kettle takes about 120 Wh, a travel hairdryer 80 to 200 Wh. Switch the inverter off afterwards: with no load, it still draws 0.5 to 1 A.
Can I use a CPAP machine in a motorhome?
On its 12 V adaptor and without a heated humidifier, a CPAP machine takes 40 to 120 Wh a night. With the humidifier, expect two to three times as much. Ask your equipment provider for the exact figures and keep a hook-up within reach if in doubt.
Sources (1)
- PVGIS, Photovoltaic Geographical Information System (monthly solar radiation) – European Commission, Joint Research Centre
These durations are estimates, not a guarantee: battery age, shade, temperature and your actual usage all make them vary. Keep an eye on your battery level, never take a lead-acid battery below 50%, and never rely on the battery alone for a medical device: keep a hook-up or a back-up solution within reach.