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Tech-Tip: Getting the most out of your auxiliary batteries

Travelling throughout North America is an awe-inspiring experience, from the inland extremes to the coastal marvels; it is why overlanding is becoming increasingly popular. Pickup trucks, trailers, and motorhomes are ideal for overland adventures, offering home comforts like communication devices, fridges, and cooking equipment. However, these gadgets rely on batteries, typically auxiliary batteries in your vehicle or trailer.  

Using battery power is easy with plugs and sockets, but recharging these batteries can be the hard part. 

Many people mistakenly believe vehicle alternators can fully recharge a flat auxiliary battery. In reality, alternators are designed to maintain the vehicle's main battery and electrical systems, not to fully recharge a depleted auxiliary battery. They can typically recover about 70-80% of a battery's charge during an average drive.  

More often than not your auxiliary batteries are a different type, size and or make to the original start battery. This combined with the limitations of the vehicle alternators makes it near impossible to effectively maintain a start battery before even thinking of the auxiliary battery. But, don’t assume for a minute that driving for hours will get you back to 100% either!  

So, what is the answer? Multi-Stage Smart Battery Charging is the only way to successfully fully charge and maintain an automotive auxiliary battery at 100%.

A good way to explain this theory is to think of your battery as an empty beer glass and your alternator as a full jug of beer. There is more than enough beer in the jug to fill the glass, however, it’s the way we pour the Beer that can drastically affect the result. For example, if we pour the beer in too fast we run the risk of too much froth. We may have filled the glass but only a small percentage is drinkable. However, we can overcome this by carefully pouring the beer into the glass and increasing the percentage of drinkable beer. Smart Multistage charging is quite simply filling your batteries in a controlled manner ensuring 100% charge back into your batteries.  

To achieve 100% charge requires regularly maintaining your auxiliary batteries with a quality 110VAC Smart Charger that offers battery type specific charging algorithms designed for your particular battery type i.e. Gel, AGM, Calcium, Standard Lead Acid or even Lithium batteries. Unfortunately, this isn’t always practical, especially if we’re off the road down some track and don’t have access to 110VAC power.  

REDARC’s BCDC range of DC/DC In-Vehicle Chargers takes the energy from the vehicle alternator and converts that energy to the correct charging requirements for your auxiliary battery. This enables the auxiliary batteries to be charged correctly whilst you’re on the move, even capturing energy from the sun when connected to a solar panel. REDARC features models ranging in output from 12, 20, 25, 40 and 50Amps however it is strongly suggested to check-in with the battery manufacturer for recommended ‘maximum’ charge currents. A base line suggestion is 20 – 25Amps for a singular auxiliary battery and 40 – 50Amps for 2 or more auxiliary batteries.  
Installation also plays a big part in the product performance. Not skimping out of quality cables, terminals and fuse holders will ensure you get the most from your investment. Remember to keep in mind, the success of the installation can have huge effects on product performance, and nobody likes arriving at camp with spoilt food and more importantly warm beer!  

Article written by Mark Bruce, REDARC Electronics Technical Training and Development Manager – North America. Mark Bruce is a qualified Auto Electrician with over 35 years' experience in the trade and wholesale automotive electrical industry.  

For more technical advice and understanding your battery needs, speak with Mark directly by contacting us