The smart way to stay in charge

In the last eight years or so, the advent of cars with so-called ‘smart’ or variable voltage alternators has forced owners to revise how they charge a secondary battery when on the go. Not far back, a dual-battery system used to power a fridge and other devices could rely on a simple voltage-sensitive relay (VSR) to reliably charge the cranking and auxiliary battery and separate them when the vehicle was switched off. This is no longer the case.

This is where ‘smart’ DC-DC (or battery to battery) chargers enter the picture. They take the highly variable (and always-changing) output from a smart alternator and increase or decrease it to a stable voltage that will ensure that a rapid and safe charge gets to the auxiliary battery, according to a controlled multi-stage charging algorithm. The higher the output from the DC-DC charger, the faster the charge rate, limited of course by the type of battery being charged. In this way, a full 100% charge can be achieved in