VAN FEATURES - Batteries & Charging
There are many different types and sizes of off-grid power systems to suit all types of van builds and budgets. We chose to go with a larger capacity system with reasonably priced components, so far it’s proven to be more than capable of keeping up with how we use power in our van.
Summary of our system:
Batteries: 4x 12V AGM batteries
Solar Charging: 400W (2x 200W Panels)
DC-DC Charging: 20AMPS max
AC-DC Charging: 40AMPS max
Batteries
We started off with 2x 105AH batteries and added 2 additional 130AH batteries giving us a total of 470AH of power. Having this many batteries allows us to stay off-grid for quite a while without needing to charge our batteries, but of course, we have solar panels to charge our batteries.
Our battery system is comprised of 4x 12 volt AGM (Absorbent Glass Mat) batteries wired in parallel. Wiring multiple 12 volt batteries in parallel keeps the voltage the same but combines all the amp hours (AH), for example, having 2x 12V 100AH batteries wired in parallel gives 200AH @ 12V, whereas if the same batteries were wired in series it would give 100AH @ 24V.
We chose to use AGM batteries mainly because they do not produce toxic and explosive gasses while charging like most lead acid barriers do, and they aren’t as expensive as lithium batteries.
Solar panels
We have 2x 200W “Rich Solar” brand Monocrystalline solar panels permanently installed up on the roof. When we purchased our solar panels the thin “stick-on” type of solar panels were still very expensive, so we opted for the full frame style. To attach the panels to our roof we used a UV stable polyurethane adhesive to attach some aluminium box tube the underside of the panel frame then glue the the whole lot directly on to the roof.
As Monocrystalline solar panels are less tolerant of partial shade we chose to wire our rooftop solar panels in parallel instead of series so we wouldn’t have to be parked in full sun get a decent charge. Wring solar panels in series will generally provide a higher charging current (more amps) but both panels need to be in full sun. By wiring our panels in parallel we can park the front or the rear of the van under a tree or in shade and still get some power without heating up the van too much. We also have an Anderson plug wired to our DC-DC chargers “solar” input so we could run an external solar panel like a folding solar panel or solar blanket without having to park the van in sun at all. We could just sit the external panel in the sun and run a cable back to the van which would be parking completely in the shade. We don’t actually have a folding solar panel or a solar panel blanket at the moment, but if we needed more solar power it’s already wired up and ready to go.
The solar panels are wired to a 40AMP MPPT solar charge controller. The solar charge controller manages the power coming from the solar panels and makes sure the batteries are getting the right amount of power. There are two main types of solar charge controllers, Maximum Power Point Tracking (MPPT) and Pulse Wave Modulation (PWM). Without going into too much detail, MPPT solar charge controllers are a better choice as they are more efficient and are available in higher charging capacities.
Other ways of charging
We also have a 20amp DC-DC charger so we can charge our house batteries while we drive. The DC-DC charger is a CTEK DS250DUAL and is wired through a high-current changeover relay which is triggered via a switch in the cabin of the van.
If we have set up camp at powered site for a few days we can also use our 40amp 240V/AC charger so we can plug in and give the house batteries recharge that way if we need. We have only used the 240V charger once so far, and that only to test it out.