In the second part of this two-part series, David explores what sort of power management system is needed for vans heading off-grid.
So, you have decided to set off on the ‘Big Lap’ and, following on from the first article in this series you have considered your energy requirements. The next steps are to help you decide what you need in a power management system when you purchase your van or when building the dream off-grid setup. Once you've got this sorted, you will then be able to escape to places off the beaten track without being worried about kids’ iPads or other electrical devices not having enough charge to watch Bluey as they fall off to sleep.
There are many parts of an off-grid caravan power system, but you don’t need all these to make a basic package of electronics. I suggest that the first step is a quality DC-DC charger that has MPPT solar capabilities. This kind of charger will mean you have solar power when driving or stationary and it will also allow you to charge devices and batteries from the alternator in your tow vehicle.
Many DC-DC chargers blend both sources of power and offer an increased power output when only utilising one source. A charger designed for under-bonnet use is the best choice, as it is likely to have higher quality internal parts that will last longer because the unit is designed to withstand extreme heat.
Products such as a BMPRO ProSmart 40 is an example of a unit built for this purpose. I suggest you don’t install any charger in the engine bay unless it clearly states it has been designed for that purpose.
Always install the charger with recommended fusing and cable thickness suitable to carry heavier amperage. For wiring to a van, use an Anderson connector at the rear of your car rather than trying to wire it into a trailer plug which isn’t suitable for a thicker gauge wire.
Secondly, you need to consider your solar system choices. If you have an option, stay away from ‘cheap and cheerful’ low-cost versions as these are generally poorly constructed and suffer from sunspot damage that you won’t see with the naked eye. However, you will notice the lack of charge going into your battery bank. Quality panels have more connections between the individual panels, and this helps if there is panel damage or shade where you can still extract quality power. I recommend a set of portable solar panels that can be added to your system when camped and can be moved around to suit the direction and angle of the sun more effectively.
It is critically important to understand the capabilities of your power management system as this can affect your experience when camped. You need to know how much energy you are generating and what your power consumption is. Additonally, connecting power inputs directly to a battery can lead to problems.
Installing DC-DC chargers and solar panels correctly to a battery requires a shunt in the circuit. In the world of DC power, a shunt is a resistor with a known resistance that is placed in series with a load, to calculate our batteries’ energy storage and remaining capacity. Effectively, this feeds valuable information to the power management system for accurate information on energy in and out of the battery. Without this you may have a load on your battery, such as an inverter connected directly, which your system cannot accurately monitor. Unfortunately this can result in an unexpected ‘blackout’ right in the middle of dinner.
Stay tuned for the next article on battery setups and the essentials you can power when camping in off-grid, remote areas of Australia.
Safe travels,
12V Guru
If you missed the first part, which explored the basic power system you'll need for getting off-grid (including lighting, water pumps, fridge, air conditioner and heater), click this link.
THE NEXT STEP
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12V Guru: Powering your off-grid caravan adventure: Part 2