Choosing the right batteries is one of the most important parts of building a reliable 12V system. A well-designed setup will keep your fridge cold, your lights running, and your gadgets charged — even when you’re off-grid for days.
This guide breaks down the different battery types, how they work, and how to choose the right size for your camper.
Your leisure battery powers everything inside your living area:
LED lights
Water pump
Fridge
Fan or heater electronics
USB chargers
Inverters (for 230V sockets)
It is separate from your van’s starter battery, which is designed for short bursts of high power (turning the engine over). A leisure battery delivers low, steady power over long periods — perfect for campervan living.
There are three main technologies you’ll come across:
A sealed lead-acid battery designed for deep cycling.
Pros
Affordable
Safe and sealed (no maintenance)
Handles cold weather better than gel
Cons
Heavy
Slower to charge
Shorter lifespan than lithium
Best for
Weekend campers, occasional off-grid use, tighter budgets.
A step up from AGM, using gel electrolyte.
Pros
Better deep-cycle performance
Extremely safe
Good for engine bays or harsh environments
Cons
More expensive
Cannot take high charge currents
Best for
Systems that must run safely in tough conditions, or where charge current is limited.
The premium option for van conversions.
Pros
Can be discharged very deeply (up to 90%)
Very light
Very long lifespan (up to 10+ years)
Fast charging
Stable voltage keeps fridges and inverters happier
Cons
Higher upfront cost
Needs a lithium-compatible charger/DC-DC charger
Doesn’t like freezing temperatures without heating
Best for
Serious off-gridders, digital nomads, long-term travellers, high-power systems.
Battery capacity is measured in Ah — amp hours.
A simple way to think about it:
1 amp for 100 hours = 100Ah
5 amps for 20 hours = 100Ah
But different battery types give you different usable energy:
| Battery Type | Rated Capacity | Usable Capacity |
|---|---|---|
| AGM | 100Ah | ~50Ah (50% usable) |
| Gel | 100Ah | ~60Ah |
| Lithium | 100Ah | ~90Ah |
👉 This is why a 100Ah lithium can replace a 200Ah AGM in most vans.
DoD is how much of the battery you can safely use:
AGM: 50%
Gel: 60%
Lithium: 80–90%
Using a lead-acid battery below 50% regularly shortens its life dramatically.
Lithium is far more forgiving.
Your leisure batteries can be charged three ways:
Old vans: basic split-charge relay
Modern vans (Euro 5+): MUST use a DC-DC charger
(smart alternators won’t charge lead-acid properly)
Great for off-grid independence. Works wonderfully with lithium.
Used when parked at campsites or at home.
To choose battery size properly, you need to know two things:
Fridge + lights + pump + fan + charging devices etc.
1 light day vs. 3 days in the mountains makes a huge difference.
To make this simple, we’re adding a Battery Selection Tool…
We’ll add a button here once the tool is ready:
👉 [Use our Battery Selection Tool]
(When the tool is complete, the link above will be live and styled properly.)
Here are some proven setups:
100Ah AGM
Basic split-charge relay
No inverter
Light loads (lights, pump, USB)
Good for: 1–2 nights off-grid
200Ah AGM or 100Ah Lithium
DC-DC charger
100–200W solar
300–600W inverter
Good for: 2–3 nights off-grid
200–300Ah Lithium
30–60A DC-DC charger
300–400W solar
1000–2000W inverter
Good for: Full-time digital nomads & long stays off-grid
Always fuse battery cables as close to the battery as possible
Use the correct cable size (use the Cable Sizing Tool!)
Ensure good ventilation for AGM/Gel
Keep lithium above 0°C during charging
Secure batteries firmly to the van floor
Use a battery monitor for accurate state of charge
A well-chosen battery setup means:
✔ your fridge won’t cut out
✔ your lights won’t dim
✔ your inverter won’t shut down
✔ you can stay off-grid as long as you want
