Campervan electrics sound complicated, but the basics are simple: you store energy in a leisure battery, you charge it in a few different ways, and you protect everything with correct fusing and cable sizes.
This guide is a plain-English UK overview so you can understand quotes, avoid common safety mistakes, and speak to converters with confidence — even if you’re not “good with electrics”.
Important: This guide is general information. Electrical work should be installed correctly and safely. If you’re unsure, use a professional.
Quick summary (the bits that matter)
A good campervan electrical system usually includes:
A leisure battery (AGM or lithium)
A safe way to charge it from the van: usually a DC-DC charger
Optional solar (panel + controller)
Optional mains hookup charging (mains charger)
Correct fuses close to the battery and proper cable sizes
A simple 12V fuse box for lights/USB/fridge/heater circuits
If a quote just says “electrics included” with no details, ask for a written spec.
1) The core parts of a campervan electrical system
Think of it like this:
The battery = the “tank”
Stores energy.
Chargers = the “refill methods”
From the engine/alternator (DC-DC)
From solar (MPPT/PWM controller)
From mains hookup (battery charger)
Fuse protection = the “safety valves”
Stops cables overheating or catching fire if something shorts.
Loads = what you power
Lights, USB sockets, fridge, heater, water pump, etc.
2) Leisure batteries (AGM vs lithium) — simple UK explanation
AGM / Lead-acid (cheaper, heavier)
Pros
Lower cost
Simple
Works fine for weekend vans with modest power use
Cons
You can’t safely use the full capacity
Heavier and slower to charge than lithium
Shorter lifespan if regularly drained
Lithium (LiFePO4) (more expensive, better performance)
Pros
You can use much more of the capacity
Faster charging
Lighter for the usable energy
Longer lifespan when used properly
Cons
Higher upfront cost
Needs correct charging setup (DC-DC recommended)
Cold-temperature charging needs consideration
Rule of thumb:
Weekend camper + lights/USB → AGM can be fine
Off-grid + fridge + heater + lots of devices → lithium is usually worth it
3) Charging from the van: split-charge vs DC-DC (modern vans)
This is a big one in the UK, especially with newer vans (Transporter T6.1 etc).
Split-charge (old-school)
Works on older alternators, but can be unreliable on “smart alternator” vans.
DC-DC charger (recommended)
A DC-DC charger:
charges the leisure battery properly
limits current (protects alternator/battery)
works properly on modern vans
If a converter quote says “split charge” on a modern van, ask if it’s actually DC-DC.
4) Solar: what it does and what you actually need
Solar is great for maintaining charge and extending off-grid time.
A basic solar setup is:
Solar panel(s) (watts)
Solar controller (MPPT is usually better than PWM)
Correct cable + fuse between panel/controller/battery
Rough expectations (UK reality):
Summer: solar can be very helpful
Winter: solar helps a bit, but don’t expect miracles
Solar is best when paired with a sensible battery size and efficient loads (LED lights, good fridge wiring, etc.)
5) Mains hookup (230V) — do you need it?
You only need 230V if you want:
to plug in at campsites
to charge the leisure battery quickly on hookup
230V sockets / appliances (kettle, laptop charger, etc.)
A safe basic mains setup includes:
A mains inlet
RCD/consumer unit protection
A proper battery charger (not a cheap “trickle” thing)
Clear separation between 230V and 12V wiring
If you’re not using campsites much, you might skip 230V sockets and just have a mains charger.
6) Fuses (the safety bit everyone should understand)
Fuses protect the cable, not the appliance.
The most important fuse
There should be a main fuse close to the leisure battery on the positive cable feeding the system.
Good signs:
Fuses are located near the battery
Each circuit (lights, USB, fridge, heater) has its own fuse in a fuse box
The installer can explain what each fuse does
Red flag: “We don’t really fuse it, it’s fine.”
No. It isn’t.
7) Common 12V loads in campervans (what uses power)
Typical 12V items:
LED lights (low)
USB chargers (low/medium)
Water pump (medium)
Diesel heater fan/glow (medium/high during startup)
Compressor fridge (medium, constant cycling)
Inverter (can be high depending what you run)
If you want, you can add a simple table of “low/medium/high” draw. (I can provide one.)
8) What to ask a converter (copy/paste questions)
If you’re paying someone, ask these:
- What battery type and capacity are you fitting?
- Is it DC-DC charging? What model?
- If solar: panel watts and controller model?
- Where are the main fuses and what ratings?
- Do I get a wiring diagram or at least a labelled fuse list?
- What circuits are included (lights/USB/fridge/heater/pump)?
- If 230V is included: what RCD/consumer unit protection is used?
A good converter won’t be offended — they’ll be happy you care about safety.
9) Red flags (simple)
No mention of fuses, cable sizing, or protection
“Split charge” on a modern smart-alternator van with no DC-DC
Quote says “electrics included” with no component list
Messy wiring, unlabeled circuits, no documentation
FAQ
Do I really need a DC-DC charger?
On many modern vans, yes — it’s the most reliable way to charge properly and protect the system. If you’ve got an older van, a split-charge relay may work, but DC-DC is still often better.
Is solar worth it in the UK?
In spring/summer, yes — it can massively extend off-grid time. In winter it helps but won’t replace driving or mains charging.
Can I just fit a big battery and no solar?
You can, but you still need a proper way to charge it (DC-DC/mains). A big battery with poor charging usually causes problems later.
What’s the single most important safety feature?
Correct fusing near the battery and correct cable sizes.
Next steps
If you’re comparing converters, ask them to list the electrical components in the quote and explain the fusing/circuit plan in plain English.