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Most caravanners assume that plugging into a powered site automatically takes care of charging their battery bank. The reality is more nuanced. Without the right caravan battery charger in your system, the power available at the site post may not be reaching your batteries at all, or it may be charging them incorrectly in a way that shortens their life. This guide covers exactly how shore power battery charging works and what you need to do it properly.

Browse our range of caravan battery chargers at Campalot including mains-powered multi-stage chargers from Enerdrive and Renogy compatible with lithium and AGM.

What Happens When You Plug Into Shore Power

When you connect your caravan to a powered site post, 240V AC power becomes available to run your appliances, charge devices and power your air conditioner or microwave directly from the mains. This part is straightforward.

What does not happen automatically is battery charging. Your 240V mains connection does not charge your 12V battery bank directly. They are different systems operating at different voltages. To transfer energy from the 240V mains supply into your 12V battery bank, you need a dedicated caravan battery charger that converts 240V AC to 12V DC and delivers it at the correct voltage, current and charge profile for your battery chemistry.

Without a caravan battery charger in your system, your batteries only charge from solar during daylight hours or from your alternator while driving. At a powered site this means you are paying for a site with power that your battery bank is not benefiting from.

What Does a Caravan Battery Charger Actually Do?

A quality caravan battery charger plugs into your 240V mains outlet and connects to your auxiliary battery bank. It manages the charging process through multiple stages to protect the battery, maximise capacity and extend service life.

Most quality chargers use a three-stage or four-stage process:

• Bulk charge: delivers maximum current until the battery reaches approximately 80 percent capacity
• Absorption charge: holds a slightly lower voltage while current gradually reduces, topping the battery to near-full capacity
• Float or maintenance charge: holds the battery at a safe voltage once fully charged, preventing overcharge while keeping it topped up during extended stays
• Equalisation (some models): a periodic controlled overcharge for AGM and flooded lead-acid batteries that helps balance cell voltages

This multi-stage process is significantly more beneficial to battery health than a simple constant-voltage charge. A battery that is regularly charged and maintained correctly through a quality caravan battery charger will last meaningfully longer than one subjected to incomplete or incorrect charging.

Lithium vs AGM: Why Battery Chemistry Matters

The correct charge profile depends entirely on your battery chemistry. LiFePO4 lithium batteries and AGM batteries have different voltage requirements, charge acceptance rates and maintenance needs. A caravan battery charger must be compatible with your specific battery type.

• AGM batteries: require a specific absorption voltage typically around 14.4 to 14.7V and a float voltage around 13.6V. Overcharging damages the cells.
• LiFePO4 lithium batteries: require a higher absorption voltage typically 14.2 to 14.6V, accept charge faster, and do not benefit from float charging. Many lithium batteries prefer the charger to stop rather than float once full.

Always confirm your caravan battery charger is explicitly rated as compatible with your battery chemistry before buying. Using an AGM charger on a lithium battery, or vice versa, will at best result in incomplete charging and at worst damage the battery over time.

Sizing Your Caravan Battery Charger

Charger output is rated in amps. The higher the amp rating, the faster the charge. A simple rule of thumb: your charger should be rated at around 10 to 20 percent of your battery capacity in Ah.

• 100Ah battery bank: a 10A to 20A caravan battery charger is appropriate
• 200Ah battery bank: a 20A to 40A charger fills the bank in a reasonable overnight period
• 300Ah or larger: a 40A or above charger is worth the investment for genuinely fast recovery

Undersizing your charger means your batteries may not reach full charge during a typical overnight stay, particularly if you are also running appliances that are drawing from the bank at the same time. Oversizing is generally not harmful for most quality chargers that regulate themselves, but adds cost without proportional benefit.

Inverter Charger: The All-in-One Option

An inverter charger combines a caravan battery charger and a pure sine wave inverter in a single unit. When connected to shore power, it charges your battery bank. When running off-grid, it inverts your battery power to 240V AC for appliances.

For a caravan or van with a complete electrical system, an inverter charger from Enerdrive simplifies the setup considerably. One device manages both shore power charging and off-grid 240V output, with automatic transfer switching between the two. This is the approach most commonly recommended for full-time travellers or anyone building a serious off-grid electrical system.

Portable Mains Battery Chargers

For caravanners who do not have a permanently installed caravan battery charger, a portable mains charger is a practical alternative. These plug into any 240V outlet and connect to your battery terminals via alligator clips or ring terminals.

Portable chargers are lighter and more flexible than fixed installations but require manual connection each time and are typically lower output than permanently wired units. They suit caravanners who spend most nights at powered sites and want a simple, reliable way to top up their battery bank without a full electrical installation.

Monitoring Your Charge

A caravan battery charger does its job automatically, but knowing the state of your battery bank matters. A quality battery monitor installed in your van gives you real-time state-of-charge data so you can confirm the charger is working correctly and track how your battery responds to regular charging cycles.

If you notice your battery never reaches 100 percent despite overnight charging, your charger may be undersized for your bank, the charger may not be configured for your battery chemistry, or your battery bank may be ageing and losing capacity.

The Short Version

Plugging into a powered site does not charge your batteries without a dedicated caravan battery charger in your system. A quality multi-stage charger matched to your battery chemistry and sized appropriately for your bank is a straightforward, important addition to any caravan electrical setup.

For a complete solution, an inverter charger from Enerdrive handles both shore power charging and off-grid 240V output in one unit. For a simpler approach, a portable mains charger covers the basics at lower cost.

  Shop caravan battery chargers and inverter chargers at Campalot - Enerdrive and Renogy options for AGM and lithium setups.