Campervan Electrical Systems: Complete Guide
A well-designed campervan electrical system is the foundation of comfortable, self-sufficient travel. Whether you are planning weekend escapes in the UK, touring Germany's backroads, or exploring the Netherlands' coastal routes, your power setup determines how long you can stay off-grid, what appliances you can run, and how quickly your batteries recover. This guide walks through every component — from leisure batteries and solar panels to inverters and monitoring — so you can build a system that genuinely fits your lifestyle.
Understanding 12V vs 230V in a Campervan
Most campervans operate on two separate voltage levels. The 12V system draws directly from your leisure batteries and powers the majority of built-in appliances: lighting, water pumps, fans, fridges, diesel heaters, and USB charging. It is efficient, safe, and well-suited to mobile environments where wiring runs are relatively short.
The 230V system replicates mains electricity inside the van. It is produced by an inverter or supplied via a hook-up cable on campsites. It allows you to run a laptop, charge power tools, operate induction hobs, and use any standard household appliance. The trade-off is that 230V appliances draw substantially more power and will deplete batteries quickly without adequate solar or alternator input.
As a practical rule: if an appliance is available in a 12V version, use it. Reserve 230V for high-power tasks that cannot be done any other way, or for periods when you are hooked up to a campsite supply.
Leisure Batteries: AGM vs Lithium (LiFePO4)
Your leisure battery bank is the heart of the electrical system. Choosing the right chemistry is the single most important decision you will make.
AGM (Absorbent Glass Mat)
AGM batteries are a mature, reliable technology. They are sealed, maintenance-free, and safe to mount in enclosed spaces. A 100Ah AGM battery delivers approximately 50Ah of usable capacity — you should not regularly discharge them below 50% if you want a reasonable service life of 3–5 years. They charge relatively slowly, perform poorly in cold temperatures, and are heavy: a typical 100Ah AGM weighs 25–30 kg.
Lithium Iron Phosphate (LiFePO4)
LiFePO4 batteries have become the preferred choice for serious vanlifers. A 100Ah LiFePO4 delivers 95–100Ah of usable capacity, accepts charge at much higher rates, and maintains a near-flat discharge curve — meaning your 12V appliances run at consistent voltage right up until the battery is empty. Service life is typically 2,000–3,000 cycles, compared to 300–500 for a well-maintained AGM. They are around half the weight of AGM for the same capacity.
The main drawback is cost — a quality 100Ah LiFePO4 costs two to four times more than an equivalent AGM. For occasional weekend use with mains hook-up access, AGM may still make economic sense. For extended off-grid travel, lithium pays for itself through longevity and usable capacity.
| Feature | AGM 100Ah | LiFePO4 100Ah |
|---|---|---|
| Usable capacity | ~50Ah | ~95–100Ah |
| Weight | 25–30 kg | 11–13 kg |
| Typical cycle life | 300–500 | 2,000–3,000+ |
| Charge rate (max C) | 0.2C (20A per 100Ah) | 0.5–1C (50–100A per 100Ah) |
| Self-discharge (monthly) | 3–5% | <2% |
| Relative cost | Lower | Higher |
Browse our range of lithium batteries for campervans — we stock Victron, Fogstar, and Battle Born options suitable for UK, German, and Dutch buyers.
Solar Charging: Panels and Regulators
Solar is the cleanest, quietest way to replenish your batteries while parked. A typical campervan installation uses between 100W and 600W of solar panels, depending on roof space, travel pattern, and power consumption.
Choosing Panel Wattage
As a rough guide, budget for approximately 10W of solar per amp-hour of daily consumption. If your van uses 50Ah per day (fridge, lighting, phone charging), a 200W panel array will keep up in UK summer conditions with 4–5 peak sun hours per day. In northern Europe in winter, sun hours drop to 1–2 per day, so sizing up generously is wise for year-round travellers.
Monocrystalline panels offer the best efficiency per square metre (19–22%), making them the standard choice for campervans where roof space is limited. Flexible panels are thinner and lighter but typically less efficient and less durable over a 10-year lifespan. Rigid framed panels are the most robust choice for most self-builds.
Explore our selection of campervan solar panels, from 100W single-panel starter kits to 400W+ arrays for full-time living.
MPPT Solar Regulators
A solar regulator (also called a charge controller) sits between your panels and battery bank. Always choose an MPPT (Maximum Power Point Tracking) controller rather than a PWM type. MPPT controllers are 10–30% more efficient, particularly important in overcast northern European conditions. They also handle higher panel voltages, allowing you to wire panels in series for reduced current losses over longer cable runs.
Victron's SmartSolar range is the benchmark in the van conversion world: Bluetooth-enabled, well-supported, and compatible with the wider Victron ecosystem. Size your controller for 125% of your panel's peak current output to allow for occasional over-irradiance conditions.
View our full range of MPPT solar regulators.
DC-DC Chargers: Charging from Your Alternator
Driving is an excellent opportunity to charge your leisure batteries from the vehicle's alternator — but only if you use a proper DC-DC charger (also called a battery-to-battery charger, or B2B charger).
Older split-charge relay systems are simple but largely unsuitable for lithium batteries: a relay allows bulk voltage to pass but cannot properly manage charge profiles, and LiFePO4 batteries charge so efficiently that they can draw more current than the alternator is rated to supply continuously, risking overheating. A quality DC-DC charger such as the Victron Orion-Tr Smart limits the charge current to a safe level, provides a full multi-stage charge profile, and can be programmed to protect the starter battery.
For most vans, a 30A DC-DC charger will add roughly 30Ah to your leisure bank per hour of driving — a valuable supplement to solar, especially in winter. Larger 40A or 60A units are available if your alternator can support higher output and you want faster charging on long drives.
Browse DC-DC chargers for campervans — including the Victron Orion-Tr Smart series.
Inverters and 230V Battery Chargers
An inverter converts 12V DC from your batteries into 230V AC mains power. Pure sine wave inverters are essential for sensitive electronics such as laptops, medical devices, and modern power supplies — avoid modified sine wave units, which can damage equipment and run motors inefficiently.
Size your inverter for the highest-draw appliance you plan to run. A 1,000W inverter covers laptops, phone chargers, and small power tools. A 2,000W unit will handle a domestic coffee machine or a small induction hob. Bear in mind that a 2,000W inverter drawing from a 12V system requires up to 170A from your batteries — heavy cables and a well-maintained battery bank are non-negotiable.
Victron's MultiPlus range combines an inverter with a mains battery charger in a single unit. When hooked up to a campsite supply, it automatically charges your batteries; when off-grid, it inverts. This is the most space-efficient solution for vans that regularly use both off-grid and on-grid power.
Explore inverters and battery chargers for all budgets and capacity requirements.
230V Mains Battery Chargers
If you rely on campsites rather than solar for recharging, a dedicated 230V battery charger is worth considering. Units like the Victron Blue Smart or Sterling range offer multi-stage charging (bulk, absorption, float) with Bluetooth monitoring, and are available in 10A to 50A output. A 30A charger will take a 100Ah LiFePO4 from empty to 80% in under three hours.
See our range of 230V battery chargers.
Fusing, Wiring and Safe Installation
Electrical fires in campervans are almost always caused by undersized cables or missing fuses. Every circuit must be protected by a fuse or circuit breaker rated for the cable, not the appliance. Use the cable, not the fuse, to determine the maximum current: 2.5mm² cable is rated to 25A, 6mm² to 50A, and 16mm² to 100A in free air (derate by around 20% when bundled or run through insulation).
Place the main fuse as close as possible to the positive terminal of your battery — within 300mm is the general rule. Use a busbars and negative distribution block to keep wiring tidy and connections secure. Tinned marine-grade copper cable is worth the extra cost for a build that will be exposed to damp and vibration over many years.
For battery banks over 200Ah, a main isolator switch between battery and distribution allows you to fully disconnect the system when the van is stored or when working on electrical components.
Battery Monitoring: Knowing Your State of Charge
A voltage reading alone is an unreliable indicator of battery state of charge — particularly with lithium, whose voltage barely changes across 20–80% charge. A proper battery monitor measures current flowing in and out of the bank (Coulomb counting) and calculates remaining capacity accurately.
Victron's BMV-712 and SmartShunt are the most popular choices in Europe. Both connect via Bluetooth to the VictronConnect app, showing real-time voltage, current, power, state of charge, and historical data. The SmartShunt is the more compact and affordable option; the BMV-712 includes a display for when you want at-a-glance readings without your phone.
Integrating your solar controller, DC-DC charger, inverter, and battery monitor into the Victron ecosystem via a Cerbo GX or Raspberry Pi running Venus OS gives you a full dashboard of your electrical system — invaluable for understanding consumption patterns and optimising your setup over time.
Sizing Your Campervan Electrical System
Start with a load audit: list every 12V and 230V appliance you plan to use, its power draw in watts, and the hours per day you will use it. Multiply watts by hours to get watt-hours per day. Divide by 12 to convert to amp-hours.
A typical couple living in a campervan full-time might use:
- 12V compressor fridge (50W average): 5–6Ah/hour = 120–145Ah/day
- LED lighting (15W total): 1.25A × 4 hours = 5Ah/day
- Water pump (60W, intermittent): ~3Ah/day
- Diesel heater (12W average): ~10Ah/day overnight
- Laptop charging (65W via inverter, 2 hrs): ~11Ah/day
- Phone charging (20W, 2 hrs): ~3Ah/day
Total: approximately 152Ah/day. With lithium batteries at 95% usable depth, you would want at least 200Ah of battery capacity to avoid daily full discharges. A 300–400Ah bank gives comfortable headroom. Pair with 300–400W of solar and a 30A DC-DC charger, and you have a system capable of year-round off-grid living in UK and northern European conditions.
The Victron Ecosystem
Victron Energy is a Dutch company and the dominant brand in European campervan electrical systems. Their product range — SmartSolar MPPT controllers, Orion-Tr Smart DC-DC chargers, MultiPlus inverter/chargers, BMV monitors, and the Cerbo GX communication hub — is designed to work together seamlessly.
All Victron devices communicate over VE.Direct, VE.Bus, or VE.Can protocols and surface data through the free VictronConnect app and the online Venus OS portal. This integration makes it straightforward to monitor, diagnose, and optimise the entire system remotely. For anyone building a serious campervan electrical system, specifying Victron throughout is a decision rarely regretted.
Frequently Asked Questions
How many solar panels do I need for a campervan?
For a typical couple using 100–150Ah per day, 200–400W of solar is appropriate for UK and northern European use. In summer this will generally keep a well-sized lithium bank topped up. In winter, supplement with a DC-DC charger from your alternator and, if needed, a 230V mains charger for overnight hookups.
Can I mix AGM and lithium batteries in the same bank?
No. AGM and lithium batteries have different charge profiles and internal resistances. Mixing them causes one chemistry to overcharge or undercharge, shortening the life of both. Always use a single chemistry throughout your leisure battery bank.
Do I need a DC-DC charger if I already have solar?
Yes — the two are complementary rather than alternatives. Solar charges when the van is stationary and there is daylight. A DC-DC charger charges whenever the engine is running, regardless of weather or time of day. In northern Europe in winter, where solar yields are very low, a DC-DC charger can be the primary charging source.
What size inverter do I need for a campervan?
For general use (laptop, phone charging, small appliances), a 1,000W pure sine wave inverter is sufficient. If you want to run a small induction hob or hair dryer, step up to 2,000W. Avoid inverters larger than your battery bank can sustain: a 3,000W inverter from a 100Ah 12V battery will drain it in under 30 minutes.
How do I know if my campervan wiring is safe?
Check that every circuit has a correctly rated fuse within 300mm of the battery's positive terminal, that cable cross-sections match the fuse rating, and that all connections are crimped or soldered rather than twisted together. If you are unsure, have the installation inspected by a qualified auto-electrician or a member of the Institute of the Motor Industry (IMI) with relevant campervan conversion experience.
