You’ve no doubt kitted out your caravan, motorhome or camper trailer with all manner of equipment. My Goldstream Gold Wing III camper trailer came from the factory with almost everything I could need. But there was one thing missing: a DC-DC charger. And fitting one became the best modification I could ever have hoped to make.
Because I prefer to free-camp, where 240V power is next to impossible to come by without a generator, the day’s drive from one destination to the next becomes a key opportunity to ensure the battery is as charged as possible, and my tow vehicle’s alternator just wasn’t cutting it.
In this case, I opted for a BMPRO MiniBoost 20A multi-stage charger; however, there are numerous such chargers on the market – it would pay to research them so as to ensure you purchase the one right for you. Essentially, a DC-DC charger is a smart-charger for your van’s 12V system that draws charge from the tow vehicle’s alternator at a higher amperage rate – up to 40A or more – than what the van’s house battery would receive without it.
A tow vehicle’s alternator alone will never really charge a van’s deep-cycle battery back to 100 percent. Why? Because as the voltage in the house battery comes close to that of the charging system, the rate of charge to the battery declines. Factor in the potential for voltage drop over, say, 7m of cable, and the picture becomes worse.
In truth, your RV’s battery would be unlikely to be charged to more than 70 or 75 per cent by just the vehicle’s alternator.
This is where DC-DC chargers come in, with their ability to boost the charge to the house battery from as low as nine or 10V to 14.4V and possibly higher. They are something that all vanners should not be without.
Take my camper trailer for example. It is fitted with a 100Ah deep-cycle battery and a 120W solar panel. My tow vehicle at the time of fitting this DC-DC charger was an 80 Series Land Cruiser. I tested the power output at the alternator and it was about 14V. However, by the time it reached the camper’s battery, it had dropped to only 11.5V. Little wonder I was having difficulty.
After the fitting a DC-DC charger, I conducted the same test and saw an immediate improvement – my camper’s battery began receiving 14.5V and its state of charge was in much better shape when I arrived at camp. An added benefit: this decreases the chances of damage being done to the battery caused by over-discharging.
Many new caravans nowadays come with a complete battery management system which will incorporate a DC-DC charger, a Maximum Power Point Tracker solar regulator to optimise the solar input, as well as a mains charger, but there are still plenty of vans on the roads with such a system that would benefit.
Since fitting a DC-DC charger, I’ve not had any issues with a depleted battery. I’ll stay at camp for a couple of days, with my solar panel putting back into the battery some of what I take out, and the DC-DC charger will bring my battery back to 100 per cent, or close to it, once I hit the road again.
If your rig doesn’t have one, I highly recommend you look into having one installed.
MEET THE AUTHOR
Max Taylor has been caravanning since he was a kid and was the editor of some of Australia’s most well-known RV publications for almost 10 years.