Leisure Battery Exploded

Our Leisure Batteries are at the heart of the electrical systems in most caravans and motorhomes and its easy to take them for granted, until the motor movers don't work or the lights won't come on!  But whilst they are just anonymous heavy black boxes that just sit here year in year out, they can be dangerous items.

What follows is going to be a generalisation of what can happen when a battery is failing.  They can fail in many ways but in this instance there are specific cues to look for.

If you find that your battery gets very hot and worse still if there's a strong smell of rotten eggs around the battery box (or inside your vehicle if the battery box is not properly sealed) then you need to act fast.  Below is a non exclusive list of things to do, obviously you need to assess your situation and take appropriate measures.

• DO NOT turn anything electrical in your vehicle on or off.
• Go to the hookup post, NOT THE BATTERY BOX and disconnect the hookup cable.
• Your battery is now no longer being charged and should cool down.
• Do not smoke near the battery!
• If you have fumes in your vehicle open some windows.
• Do Not Switch on any electrical items until long after the smell has gone
• Once your battery is cool, it needs to be replaced.

Whats going on?

In simple terms, the battery is appearing as "dead" to the charger, which pumps in electricity to try to revive it, the battery cannot "take" the charge as its no longer working as it should and starts to get hot.  As it heats up, the acid in the battery gives off gases and pressure builds inside the case.  some venting can occur releasing the gas (which is explosive).  Any ignition source can cause the battery to explode.

What if it does explode!

The battery box should contain the worst of the blast and the tray that the battery sits in, inside the battery box, should capture most of the acid.

• Rinse the whole area with water to avoid acid marks in paintwork or on trims.​
• Carefully remove the battery after disconnecting the hookup cable, remembering to use protective gloves to avoid getting acid on you.
• Research how you can dispose of the battery and acid in your area (don't tip it down the drain!).
• Its likely that the battery box will be damaged, its important that its replaced it will weakened and probably cracked so will no longer keep any future fumes out of your vehicle.

First hand Experience

I thought I would put page this together as I recently experienced a battery explosion and was lucky not be injured.  When I got into the caravan I immediately smelt fumes and got out and removed power from the vehicle.  I walked around to the battery box (luckily its door was open) and as I got close the pressure in the battery must have got too much and it exploded with a very loud and sharp boom.  I suspect that as the casing cracked open a spark ignited the gas.  The photos on this page show whats left, note that the acid and some shrapnel is contained in the battery tray.