Choosing the right leisure battery is one of the most important parts of designing your campervan electrical system.
Go too small and you could find yourself constantly worrying about running out of power. Go unnecessarily large and you're adding cost and weight — while potentially ending up with a battery bank that your charging system struggles to replenish.
So, what size leisure battery do you actually need for a campervan?
The answer depends on how much electricity you use each day, how long you want to stay off-grid and how you're able to recharge your batteries.
Rather than guessing whether you need 100Ah, 200Ah or 300Ah, there's a relatively simple way to work it out.
What Size Leisure Battery Do I Need? The Short Answer
For many campervans using lithium batteries, the following can be useful starting points:
| Campervan Use | Typical Lithium Battery Capacity |
|---|---|
| Weekend trips & lighter electrical use | Around 100Ah |
| Touring with fridge, devices & laptop | Around 150–200Ah |
| Longer off-grid stays & higher demand | Around 200–300Ah |
| Heavy inverter use & larger systems | 300Ah+ |
These are only general planning ranges.
Two campervans with exactly the same 200Ah battery could have completely different experiences depending on what appliances they're running and how often they're able to recharge.
The best place to start is with your daily energy consumption.
Start With Watt-Hours, Not Just Amp-Hours
Campervan batteries are usually advertised in amp-hours (Ah).
You'll see batteries described as 100Ah, 200Ah, 300Ah and so on.
The problem is that most electrical appliances are rated in watts (W).
To make battery sizing easier, it helps to convert everything into watt-hours (Wh).
The calculation is:
Battery Voltage × Amp-Hours = Watt-Hours
For example, a nominal 12V 100Ah battery stores approximately:
12V × 100Ah = 1,200Wh
If we're looking at a lithium battery with a nominal voltage of 12.8V:
12.8V × 100Ah = 1,280Wh
That means a 12.8V 100Ah lithium battery has approximately 1,280Wh of nominal stored energy.
But there's an important distinction here.
Nominal capacity isn't necessarily the same as the amount of energy you should plan to use.
Battery chemistry, manufacturer limits, temperature, age and discharge rate can all affect usable capacity.
We'll come back to that shortly.
Step 1: Calculate Your Daily Campervan Energy Use
The first step is to work out roughly how much electricity your campervan uses during a typical day.
For example:
| Appliance | Approx. Daily Energy Use |
|---|---|
| Compressor fridge | 360Wh |
| LED lighting | 40Wh |
| Phones & tablet | 50Wh |
| Laptop | 120Wh |
| Pump, fan & controls | 80Wh |
| Total | 650Wh per day |
Our example campervan therefore needs approximately 650Wh of energy each day.
Your own figure could be considerably higher or lower.
A simple weekend camper with lighting, USB charging and a fridge may use relatively little electricity.
Add laptops, televisions, coffee machines, induction cooking or other 230V appliances and your daily consumption can increase significantly.
Don't Forget About Your Inverter
If you're running 230V appliances through an inverter, you also need to account for the energy used by the inverter itself.
An inverter isn't 100% efficient, so some energy is lost while converting the battery's DC power into 230V AC.
There can also be standby consumption while the inverter is switched on, even when you're not actively using a 230V appliance.
High-powered appliances create another consideration.
Something such as a kettle might only run for a few minutes, but it can still demand a very large amount of current from a 12V battery while it's operating.
That's why battery sizing isn't only about how much energy the battery stores.
You also need to know how much current it can safely supply.
Step 2: Decide How Long You Want to Stay Off-Grid
Once you know your approximate daily consumption, think about how long you'd like your campervan to operate without meaningful charging.
The basic calculation is:
Daily Energy Use × Days Off-Grid ÷ Usable Battery Fraction = Required Nominal Capacity
Let's use our example of 650Wh per day.
If we want enough battery capacity for two days:
650Wh × 2 = 1,300Wh
So we need approximately 1,300Wh of usable energy.
If our planning assumption allows us to use around 80% of the lithium battery's nominal capacity:
1,300Wh ÷ 0.8 = 1,625Wh
At 12.8V:
1,625Wh ÷ 12.8V = approximately 127Ah
Rather than trying to find a 127Ah battery, you would normally move up to a commonly available capacity.
In this example, something around a 150Ah lithium battery could therefore be a sensible starting point, subject to the battery manufacturer's specifications and the rest of the electrical system.
Why You Should Leave Some Battery Reserve
It's tempting to size a battery so that your calculations use every last watt-hour available.
In reality, having some reserve makes your campervan much more comfortable to use.
Imagine you've calculated your system based on two sunny days followed by a drive.
Then the weather changes.
Solar production drops, you stay in the same location for an extra night and your fridge works harder because it's particularly warm.
Suddenly, your carefully calculated energy budget doesn't quite work.
Leaving some reserve gives you a buffer for:
- Poor weather
- Longer stops
- Unexpected electrical use
- Reduced solar production
- Shorter-than-planned journeys
- Conversion losses
The amount of battery capacity you should consider usable also depends on the specific battery.
Always follow the battery manufacturer's recommendations rather than assuming that one depth-of-discharge figure applies to every battery.
Lithium vs AGM Leisure Batteries
One of the biggest decisions when choosing a campervan leisure battery is the battery chemistry.
Two of the options you're likely to come across are lithium iron phosphate (LiFePO4) and AGM.
They can both be used in campervan electrical systems, but they have very different characteristics.
Lithium Leisure Batteries
Lithium iron phosphate batteries have become extremely popular in modern campervan conversions.
Some of their main advantages include:
- High usable capacity for their size
- Lower weight compared with equivalent AGM capacity
- Low voltage sag
- Strong cycle life when correctly used
- Ability to support capable off-grid systems
Lithium batteries can be particularly attractive when space and payload are limited.
However, they need to be installed as part of a lithium-compatible electrical system.
Your solar controller, DC–DC charger and mains charger all need suitable charging profiles.
The battery's Battery Management System (BMS) is also extremely important.
Another consideration is temperature.
Many lithium batteries must not be charged below their permitted temperature unless the battery includes suitable low-temperature charge protection or heating.
Always check the specifications of the particular battery you're installing.
AGM Leisure Batteries
AGM batteries can still make sense for lighter-use campervan systems.
They will often cost less initially than lithium batteries, which can make them attractive for simpler builds.
However, AGM batteries are generally:
- Heavier for the same usable energy
- Larger for equivalent usable capacity
- Better suited to shallower cycling
- More dependent on receiving regular full charging
This means you shouldn't compare lithium and AGM batteries purely by looking at the Ah number printed on the side.
A 100Ah lithium battery and 100Ah AGM battery won't necessarily give you the same practical usable energy or ownership experience.
What Size Lithium Battery Should I Get for My Campervan?
There's no universal answer, but these ranges can help with initial planning.
Around 100Ah Lithium
A 100Ah lithium battery can work well for a compact campervan with efficient 12V appliances and regular access to charging.
It may suit a setup running things such as:
- Compressor fridge
- LED lights
- Phone charging
- Water pump
- USB devices
It's particularly practical if you're regularly driving and using a DC–DC charger to replenish the battery.
Around 150–200Ah Lithium
This is a useful range for many touring campervans.
It provides more flexibility for:
- Compressor fridge
- Lighting
- Phones and tablets
- Laptop charging
- Fans
- Pumps
- Longer periods between charging
For people who want to spend several days away from campsites without building a particularly large electrical system, this can be a good area to consider.
Around 300Ah Lithium or More
Larger battery banks start to make sense when you're running higher electrical loads or spending longer periods off-grid.
This could include regular use of an inverter for 230V appliances.
However, simply fitting a huge battery isn't necessarily the solution.
The larger your battery bank becomes, the more important your charging system becomes.
There's little benefit in having an enormous battery if your solar panels and DC–DC charger can't replace the energy you're using.
Battery Capacity Isn't Everything
One of the most important things people overlook when choosing a leisure battery is its maximum discharge current.
Imagine you have plenty of battery capacity and install a powerful inverter.
A 2,000W inverter on a 12V system can demand well over 160A from the battery before you even account for inverter losses.
Your battery therefore needs to be capable of supplying that current.
Check both the battery and BMS specifications for:
- Continuous discharge current
- Peak or surge discharge current
- Maximum charge current
The rest of your electrical system also needs to be capable of safely handling the load.
That includes:
- Battery cables
- Fuses
- Isolators
- Busbars
- Shunts
- Connections
A battery can contain enough energy to run an appliance while still being unable to provide the instantaneous current that appliance requires.
Your BMS Matters
Most modern lithium leisure batteries include a Battery Management System, commonly called a BMS.
The BMS helps protect the cells against operating conditions outside the battery's permitted limits.
When you're choosing a battery, don't just look at the headline Ah capacity.
If you're planning to run a large inverter, check whether the BMS can actually support the required discharge current.
For example, a large-capacity battery with a relatively low BMS discharge limit could still restrict the size of inverter you can practically use.
This is why the battery and inverter should be sized together.
Make Sure You Can Recharge Your Leisure Battery
This is arguably just as important as choosing the battery itself.
A bigger battery gives you more stored energy, but once you've used that energy, you need a way of putting it back.
Your campervan might use a combination of:
Solar charging – replenishes the battery while suitable sunlight is available.
DC–DC charging – charges the leisure battery from the vehicle electrical system while you're driving.
Mains charging – allows the battery to recharge when you're connected to campsite or home hook-up.
Imagine your campervan uses 650Wh per day, but your charging sources only replace around 350Wh.
You're losing approximately 300Wh from the battery every day.
A larger battery would allow you to continue for longer, but it doesn't fix the underlying energy deficit.
Eventually, the battery will still run down.
The goal should be to build a system where your charging sources can realistically replace the amount of energy you use.
Battery Size and Solar Should Work Together
This is why we recommend thinking about your campervan electrics as a complete system.
A large battery paired with a tiny solar panel may take a very long time to recover when you're parked.
Likewise, installing a large solar array with a very small battery could mean you don't have enough storage to make full use of the energy available.
Your:
- Leisure battery
- Solar panels
- MPPT controller
- DC–DC charger
- Mains charger
- Inverter
should all be considered together.
Do You Need a Battery Monitor?
A battery monitor is one of the most useful additions to a campervan electrical system.
Rather than trying to estimate how much battery capacity remains from voltage alone, a shunt-based battery monitor measures the current flowing into and out of the battery.
This can help you understand:
- Your battery's state of charge
- How much power you're currently using
- How much energy you've consumed
- Whether your solar is keeping up
- How much charge you're gaining while driving
Most importantly, it helps you understand how your campervan actually behaves in the real world.
You might calculate that you use 650Wh per day, only to discover that your actual consumption is very different.
A good battery monitor gives you the information needed to adjust your habits or electrical system accordingly.
Fogstar Drift ECO Lithium Leisure Batteries
At Nomadic Leisure, we stock the Fogstar Drift ECO lithium leisure battery range alongside Victron charging, monitoring and electrical equipment.
Options such as the Fogstar Drift ECO 12V 314Ah lithium leisure battery provide substantial capacity for larger campervan electrical systems.
But the biggest battery isn't automatically the best choice.
The correct capacity depends on your electrical loads, inverter requirements, charging capability and how you actually use your van.
That's why, when designing a new electrical system, we recommend sizing the battery, inverter, solar and charging equipment together rather than choosing each component separately.
Common Campervan Battery Sizing Mistakes
1. Choosing a Battery Based Only on Ah
Amp-hours don't tell the whole story.
Convert capacity into watt-hours so you can compare the battery directly with the energy your appliances consume.
2. Buying the Biggest Battery Possible
More capacity can be useful, but only if your charging system can realistically replenish it.
3. Ignoring the BMS Discharge Limit
This is particularly important when using a large inverter.
Make sure the battery can safely supply the current your inverter requires.
4. Forgetting About Winter
Reduced solar production can dramatically change how long your battery lasts between charges.
5. Comparing AGM and Lithium Like-for-Like
The same Ah rating doesn't necessarily mean the same usable energy.
Battery chemistry matters.
6. Sizing the Battery Separately From Everything Else
Your battery, inverter, solar and chargers all affect one another.
A balanced electrical system is much more useful than one oversized component.
Frequently Asked Questions
Is 100Ah Enough for a Campervan?
For a campervan with efficient 12V loads, shorter trips and frequent access to charging, 100Ah can be enough.
If you're regularly using laptops, spending several days parked or relying heavily on an inverter, additional capacity may be more comfortable.
Is 200Ah Enough for a Campervan?
For many touring campervans, 200Ah of lithium capacity can provide a useful balance between capacity, size and weight.
Whether it's right for your setup still depends on your daily consumption and charging options.
Someone using 400Wh per day will have a very different experience from someone using 1,500Wh per day, despite having exactly the same battery.
Is 300Ah Too Much for a Campervan?
Not necessarily.
A 300Ah+ lithium battery can make sense for higher-demand systems, longer off-grid stays or regular inverter use.
The important question is whether the rest of your system is designed around it.
Your solar, DC–DC charger and mains charging need to be capable of replenishing the energy you use.
Can I Replace an AGM Battery With Lithium?
Not automatically.
Before changing from AGM to lithium, check:
- Solar charge-controller settings
- DC–DC charger compatibility
- Mains charger profile
- Battery-management requirements
- Low-temperature charging behaviour
- Cabling
- Fusing
- Alternator-charging arrangement
Don't assume that changing the battery is simply a like-for-like swap.
Do I Need a Battery Monitor?
A shunt-based battery monitor is strongly recommended if you want an accurate understanding of your electrical system.
It makes it much easier to see whether you're consuming more energy than your solar, DC–DC and mains chargers are replacing.
So, What Size Leisure Battery Do You Need?
The best campervan leisure battery isn't necessarily the biggest one you can afford.
It's the battery that matches the way you actually use your campervan.
Start by calculating your approximate daily energy use in watt-hours.
Then decide how many days of reserve you want, account for the usable capacity of your chosen battery and make sure the battery can provide enough current for your highest-powered appliances.
Finally, check that your solar, DC–DC and mains charging system can realistically put that energy back.
For lighter campervan setups, around 100Ah of lithium capacity may be enough. Many touring systems may benefit from 150–200Ah, while higher-demand off-grid systems and regular inverter users may look towards 300Ah or more.
At Nomadic Leisure, we stock Fogstar Drift ECO lithium leisure batteries alongside Victron solar, charging, inverter and battery-monitoring equipment.
If you're building a new system and aren't sure what capacity you need, speak to the Nomadic Leisure team about a complete campervan electrical design. We can help you balance your battery capacity, solar, DC–DC charging and inverter around the way you actually travel.
