External Battery Storage Issues You Should Know About
What are the best practices and recommended storage solutions for batteries in caravans?
Question: I have noticed many new caravans now have their electrical batteries installed externally, in a metal box attached to the caravan chassis. I’m assuming this must be a new safety requirement to safeguard sleeping occupants against off-gassing batteries?
However I’d be grateful to know of any maintenance issues associated with this new battery set-up? (Eg, temperature extremes, potential theft, off-roading clearance and maintenance checks? (from Anthony McDermott)
Answer (David Bayliss): Thanks for your question – a great observation. You are correct that the industry and standards in the Australian RV space are continuing to improve all the time and, as such, caravan manufacturers will move to storage of lead acid batteries (AGMs) outside of the living space. As you would be aware, when charged too quickly AGM batteries can build up hydrogen faster than its own ability to be absorbed back into the glass mat inside the battery. The batteries have a small vent normally located near the top that, under the right pressure (1-2PSI), allows excess toxic hydrogen gas to vent to the outside atmosphere. And this is where the problem begins.
Storage is at a premium inside caravans, so manufacturers normally only allow a small cavity for the battery either under the bed or under a seat in the dining area. These spaces are not always vented to the interior or exterior of the van which means that this venting could create a build up of dangerous hydrogen gas which, with the right conditions, can become an explosive flammability hazard. This issue is further exacerbated when travellers fill every spare pocket of space with ‘essentials’ such as spare towels, pillows etc which block the ventilation that was installed during manufacturing. Therefore, in light of the above-mentioned safety aspects, manufacturers are moving towards storage of lead acid batteries on the outside of the RVs.
Strong steel fabricated battery lockers are now being added to chassis frames and it’s critical to ensure that these are not only well made but can also secure the battery to prevent damage from movement and vibration. When considering purchasing a van check to see how the battery has been secured into the external locker. A battery that can be moved by a simple finger poking through the metal frame means that on road it will certainly be subject to excessive wear and tear due to vibration. Inside the plastic case of the battery are suspended glass mat separators and lead plates which are positioned vertically. Excessive vibration or external physical shock can cause these to break and create an internal short circuit thus damaging the batteries. Often, we see adding solid rubber around the base or sides of the battery can prevent this vibration from becoming an issue.
We wouldn’t expect that securing of the batteries from theft is a big issue, but you can never be too sure. Not an easy task for a would-be thief to climb under a van and manoeuvre close to 30kg of battery from its enclosure, but a latch and padlock will visually and physically deter most thieves.
Maintenance of your battery will substantially increase when compared to a battery stored inside with the potential of corrosion of terminals and cabling which are now heavily exposed to the elements. Dust and grime naturally build up on the underside of any vehicle from tyres, the road and general weather or road conditions. With batteries stored on the outside of the caravan regularly inspecting for any build-up at the battery terminals will be critical as the slightest loose connection will allow build-up of corrosion, reducing a good clean secure electrical connection. Be conscious also of potential degradation of cable sheathing for the same reasons. Regular checking of connections and overall condition is recommended.
As to clearance on the underside of your chassis, you should find that smart manufacturers have located the battery locker where it is afforded some protection from the environment, is easily accessible for battery changeover or maintenance and is located as close to the chassis frame as possible to maintain adequate clearance.