Do I need that Battery Management System thing and what is it?

Your van comes as standard with a Bluetooth battery monitor which connects to a smartphone and will tell you your battery/charge history and the amount of power left in your battery (in % and volts but not measured in time). This is handy.   

What about the other battery management product we sell? 

You don’t NEED it.  But if you are planning on doing mainly free camping/national park camping without 240 volt power then this system gives you piece of mind as it tells you exactly how much power you have left in hours if you continue doing exactly what you are doing at that point in time.  So if you are running a fridge and have a laptop plugged in it might for example say 4 hours.  But then you plug in your solar blanket and it recalculates to 8 hours. Then your laptop battery is full and you unplug the charger and the system recalculates to 12 hours.