G’day Tony,

You’ve picked up on an interesting trend in modern caravan design. More manufacturers are opting to mount lithium batteries underneath the van, secured in vented boxes on the chassis. The main reason for this is space efficiency is the new Australian Standards (AS/NZS 3001.2.2022) which were released around 18 months ago and were interpreted as being that if you can provide a sealed, externally vented internal location the most practical solutions was to mount the batteries externally. Most manufacturers chose to therefore chassis mount

But, as you rightly pointed out, this raises questions about durability, safety, and exposure to water and harsh conditions. It’s a topic that’s got a few people scratching their heads, so let’s break it down.

How Waterproof Are Lithium Batteries?

Most lithium batteries used in caravans come with a protective casing and an IP (Ingress Protection) rating exactly the same as lead acid batteries. This rating determines how well the battery is sealed against dust and moisture. Many lithium batteries are rated IP65 or higher, meaning they can handle dust and low-pressure water jets but are not designed for full submersion.

So, while a quick splash from wet roads or rain won’t cause problems, driving through deep water, such as creek crossings, could be risky. This is the same whether it is a lead acid or a lithium battery as both use the same casing in most cases.  An IP54 rated battery is most likely not glued or heat sealed between the base and the top and not likely to have a gasket installed either. Whereas a fully IP67 rated battery will have a full gasket seal preventing all dust or water ingress making it suitable for submerging briefly whilst crossing rivers or creeks. Batteries such as the Invicta X Series rate well for this purpose.

The Role of Battery Boxes and Venting Requirements

To comply with Australian regulations, lithium battery enclosures must be vented. This is mainly a safety measure, as batteries can release gases in extreme failure scenarios, and enclosed spaces must allow for proper dissipation.

Here’s where the challenge comes in: vented boxes allow air circulation but can also let water in. If a caravan is regularly exposed to river crossings, deep puddles, or high-pressure hose cleaning underneath, it’s critical that the battery box is designed with drainage points or proper sealing to prevent water pooling around the battery terminals.

Is This a Good Idea for Off-Roaders?

For those staying mostly on highways and sealed roads, chassis-mounted lithium batteries are generally fine—they free up space inside and keep weight distribution optimal – meet all regulations.

For off-road adventurers regularly tackling deep creek crossings, mud, and extreme conditions, there’s more to think about. If the battery isn’t IP-rated for full submersion, you might want to rethink placement or invest in additional waterproofing.

Let’s think through this though. Most river or creek crossings are a temporary splashing of water so an IP54 battery is more than suitable. If your RV is water submerged for a period over time over the top of chassis mounted batteries, there will be more damage to worry about inside your van than the state of the batteries.

What can you do if your caravan already has a chassis-mounted battery?

• Check the manufacturer’s specs – What’s the IP rating of the box and battery?
• Consider additional shielding – Some owners add an extra splash guard.
• Inspect after water crossings – A quick post-trip check can prevent long-term issues.

Final Verdict – Smart or Risky?

Mounting lithium batteries under a caravan isn’t necessarily a bad idea, but it requires careful planning. If done right—with properly rated enclosures, waterproof terminals, and regular checks—it can work well.

But if you’re planning serious off-road adventures, take a close look at your battery setup before tackling deep water crossings. A little extra precaution now can save you from a major headache down the track.

Hope that clears things up, Tony! Stay charged and travel safe.

Safe travels

12V Guru