But there’s one important catch we want you to know upfront:

In most older setups, a Lithium upgrade will require a DC–DC charger (and sometimes a couple of other small system tweaks) to make sure everything charges properly and safely.

Why a DC–DC charger matters (in plain English)

AGM and Lithium batteries don’t “eat” power the same way.

1) Lithium batteries pull power harder

Think of it like this:

• AGM is like a sponge that soaks up water slowly as it gets fuller.
• Lithium is like a wide open funnel — it can pull a lot of charge very quickly.

In older campers, the battery is often charged from the car via a basic relay or direct feed (common in older builds). That setup can allow too much current to flow, which can:

• put extra strain on the tow vehicle’s charging system/alternator
• cause voltage drop issues (meaning the Lithium never charges properly)
• lead to inconsistent charging (especially on modern vehicles)

2) Lithium needs the right charging “recipe”

AGM batteries and Lithium batteries like different charging profiles (the voltage and stages used while charging).

Older charging setups were usually designed around AGM behaviour, which can mean your Lithium battery:

• charges slowly (or not fully)
• cuts in and out
• doesn’t get the correct voltage it needs to charge efficiently

A DC–DC charger fixes this by taking whatever the car is supplying and delivering a clean, controlled charge that matches the Lithium battery’s requirements.

3) Modern vehicles can make it worse

Many newer tow vehicles use “smart alternators” that change output to improve fuel economy. This can cause older camper charging setups to behave unpredictably.

A DC–DC charger helps by:

• stabilising the charge going to the camper battery
• boosting voltage when needed
• protecting the system by limiting current draw

What a DC–DC charger actually does

A DC–DC charger is basically a traffic controller for charging power coming from your vehicle.

It will:

• deliver the correct charging profile for Lithium
• limit current draw to a safe level
• help ensure your Lithium battery charges properly while you drive
• often work alongside solar charging (depending on the model)

What else might need changing?

Depending on your setup, a Lithium upgrade may also require one or more of the following:

• 240V charger settings (some older 240V chargers don’t have a Lithium mode)
• Solar controller settings (it may need to be set to Lithium, or upgraded if it can’t)
• Cable size and fusing (Lithium can draw higher current, so wiring protection matters)
• Battery monitoring (some monitors are AGM-focused and won’t read Lithium accurately)

None of this is unusual — it’s just part of upgrading to a newer battery technology.

Is the upgrade worth it?

For many owners, yes. Lithium batteries can offer:

• more usable capacity
• faster charging
• better performance for free camping
• longer lifespan (when set up correctly)

The key words are: when set up correctly.

Important note on installation

Battery upgrades involve high current electrical work. For safety and warranty reasons, we recommend the DC–DC charger (and any wiring changes) are installed by a qualified auto electrician or experienced 12V installer.

FAQ

Can I upgrade to Lithium without a DC–DC charger?

In some situations you might be able to, but in most older Mars Camper setups it’s not recommended. The main reasons are:

• the tow vehicle charge feed may not deliver the right voltage for Lithium
• Lithium can draw high current, which can strain wiring and the vehicle charging system
• charging can become inconsistent (especially with newer “smart alternator” vehicles)

A DC–DC charger is the simplest way to make the system reliable and safe.

What size DC–DC charger do I need (20A / 25A / 40A)?

It depends on your battery size, wiring, tow vehicle, and how you travel.

• 20–25A is common for single-battery setups and regular touring.
• 40A+ can suit larger Lithium banks, but only if the wiring and fusing are sized correctly.

If you’re unsure, ask your installer (or send us your model/year and battery details) so you don’t over-spec something your wiring can’t support.

Do I need to change my 240V charger if I go Lithium?

Sometimes. Some older 240V chargers were designed for AGM only. If the charger doesn’t have a Lithium profile, it may not fully charge Lithium correctly or may hold the wrong voltage.

Your installer can confirm whether your current charger is Lithium-compatible or whether it needs upgrading.

Do I need to change my solar controller?

Possibly. Many solar controllers can be switched to Lithium mode (or have a custom profile). If yours can’t be adjusted, it may need to be replaced so it charges Lithium properly.

Will Lithium charge faster than AGM?

Usually, yes. Lithium can accept charge quickly and stays efficient through most of the charge cycle. That’s one of the big benefits — as long as you have the right chargers and wiring in place (including a DC–DC charger for vehicle charging).

Will a Lithium battery work in cold weather?

Most Lithium batteries have protections built in (BMS). Some Lithium batteries should not be charged below certain temperatures unless they have a low-temp cut-off or internal heating. If you camp in cold conditions, choose a battery suited to that use.

Why does my mate’s camper “just work” when they swapped to Lithium?

Different campers and different vehicles have different charging setups. Some people get lucky for a while — until they don’t (slow charging, flat batteries, or weird electrical behaviour). A proper DC–DC charger setup is about making it reliable, not “it seems fine so far”.

What info should I send you if I want advice?

To point you in the right direction quickly, send:

• model + year
• tow vehicle (make/model/year)
• current battery type and size
• what Lithium battery you want to install (if chosen)
• photos of your 12V area, charger, and solar controller labels

That gives us enough to suggest what needs to change (and what can stay).