Many modern Four Wheel Drives used for towing caravans incorporate fuel-saving and emission-reducing technologies such as temperature-compensating and variable-voltage alternators.
While great for the environment, they are not so great if you're relying on the tug to top up a battery in the tow vehicle. This is where DC-DC chargers come in. They take the low voltage, high amperage output of the alternator and boosts the voltage to a point that the battery can charge from it.
Now, not everyone will need a DC-DC charger and those that have cars with these alternators may not get a benefit from using one. As such, it's important to take a look at a few factors before taking the plunge.
The most important factor to take into consideration when looking at whether to buy a DC-DC charger is how you plan to use your van.
If you're planning to travel to one spot and stay there a few days before travelling home, a DC-DC charger generally won't be of any benefit to you.
Likewise, if you're travelling to a freecamp site, staying there a while and then travelling to a powered site, you're just going to get powered up from the mains once there. You will get little to no benefit in this scenario.
Where the DC-DC chargers come into their own is when you are planning to do lots of free camping, site to site, without going to powered sites in between. Even better if you're planning to drive 3-4 hours or more in between each stop. This will often have the batteries low when you leave and allows the DC-DC charger to work at its maximum rate the entire drive.
This isn't to say there is no benefit in the previous scenarios, only that the benefit is diminished.
If you're planning to use DC-DC charging, we recommend using the BMPRO MiniBoost. Refer to our article "How do I add a MiniBoost to my system?" for more information.
While other brands can be made to work, the MiniBoost is 100% compatible with the systems we use and will work with the protection systems in place.
Be careful when choosing a third party DC-DC charger as many on the market can only be connected directly to a battery as they require feedback from the battery. These will not be able to turn on due to the protection circuits inside your Battery Managemen System.