Having a dual-battery system makes good sense: you can isolate the starting battery while using a secondary slave to power a fridge, camp lighting, accessories or phone chargers, camera batteries and the like. But even the strongest battery will succumb to the power demands being placed on it over a week away.
So how do we extend the useability of the secondary battery?
Generators are ideal when 240V is needed but their 12V output is a poor substitute for a modern multi-stage battery charger. They're heavy, take up space, need fuel and are noisy - hence the restrictions on when and where you can use them to ensure fellow campers can enjoy the tranquillity of their surroundings. And, no, running your engine at 1500rpm for several hours a day shouldn't be a stealth substitute for a generator.
Solar is free, clean, environmentally friendly and silent. The three common designs are fixed, folding or flexible panels. Fixed panels are generally cheaper. Being bulky and heavier than flexible or folding panels, they are generally mounted or have a storage cradle on campers and caravans as it's easy to damage them if packed flat with gear on top. If real estate in the vehicle is at a premium, flexible or folding panels are compact, lightweight and easy to set up and position to get the best morning or afternoon sun.
We've been using a Projecta 120W folding panel for eight months. The unit has had a hard workout keeping the dual vehicle batteries topped up and providing additional input for the camper when needed.
At only 7kg, the Projecta unit is complete with everything, including the essential in-built solar regulator controlling output and protecting battery discharge. Simply unfold, hook up and begin charging. Its compact form is thanks to the six lightweight, frameless fibreglass-backed mono-crystalline panels mounted in a functional 36x50cm black canvas wallet with a deep side pocket to house the metal support stays, 5m wiring harness and battery clamps. There are reinforced eyelets for securing in windy conditions.
Positioning the stays correctly will ensure proper support for the panels and avoid any premature fraying of the canvas. A minor nicety to improve functionality would be the ability to disconnect the battery clamps from the harness via a standard 50-amp Anderson connector and connect directly to a vehicle or camper trailer, rather than raising the bonnet or opening the battery box.
Projecta quotes 7.52 amps and 21V in perfect (that is, controlled) conditions. However, achieving an open-circuit voltage of 19.2V with 6.2 amps for the short-circuit current test in the real world was still impressive.
With a recommended retail price of $989, the Projecta 120W panel has performed admirably in a range of conditions. The compact, lightweight self-contained design is a stand-out feature.
For more information on Projecta's range of solar solutions, visit projecta.com.au