DC-DC Battery Chargers & Alternator Charging

An unbiased opinion on DC to DC Battery Chargers The straight facts about DC - DC battery charging by Collyn Rivers.

DC-DC Alternator Charging

(an unbiased opinion)

A vehicle alternator is engineered to provide a running vehicle’s electrical needs including recharging the starter battery. The requirements for charging an RV’s batteries however are different: not least as the specialised batteries have very different charging requirements. Because of this, traditional such charging has been very much a compromise, particularly with camper trailers and caravans – where the RV battery is at a distance.

Since 2000 or so it has been complicated by alternator voltages falling. Soon they are likely to be (at 12.7 volts or so) too low for RV battery charging at all. It is also complicated by the use of computer engine control systems that require a constant voltage. With these, traditional RV battery charging may or may not affect them, but tends to be blamed regardless for any engine computer faults.

The now totally tested and proven solution – for all such issues (old or new) is dc-dc alternator charging. This is one of those rare breakthroughs (like turbo-charging) that really does work.

In essence it is ‘seen’ by the alternator as just another harmless load (like a pair of spot lights or an audio system). It accepts whatever voltage that alternator produces and converts it, not only into the now higher voltage required for RV battery charging – but that required for the capacity and type (sealed deep cycle, AGM, gel cell etc) of the battery/s you are using.

As it does not interfere with starter battery charging in any way, the huge benefit of dc-dc charging is that, for camper trailers, fifth wheel and conventional caravans, it can be located close to the battery/s in that trailer – thus totally overcoming otherwise inevitable voltage drop.

Adequate sized cable is still needed to avoid energy loss, but that dc-dc alternator charger will ensure full charging voltage at that remote battery. This must be made very clear if having it professionally installed or the lightest possible cable will be used. It is not hard to install yourself though and, in that case, buy proper sized cable to do it. That (twin core) cable is not cheap, but is really needed to optimum results.

The dc-dc alternator charging system is genuinely so effective that, in my books on these matters (and also on my website), I recommend that no other type of charging system even be considered.

Full details are in my all new Caravan & Motorhome Electrics - also now used by some TAFE colleges in their auto-electrician training courses. (Please note that I make no recommendations here, or in my books, for specific brands.)

Collyn Rivers.

(This article is reproduced here by express permission: – copyright 2014: Caravan & Motorhome Books, PO Box 356, Church Point, NSW 2105).

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