No announcement yet.

12v solar and electric system diagram for VW T25 Camper

  • Filter
  • Time
  • Show
Clear All
new posts

  • 12v solar and electric system diagram for VW T25 Camper

    We've just started planning the solar and electric system for our VW T25. We are new to electrics and solar so have been doing a lot of research to get to the point where we have an initial diagram of how we are thinking everything should be wired.

    We would really appreciate any feedback on this.

    Our requirements for the electric system are:
    • DC circuit to power compressor fridge, vent fan, led lights, usb sockets
    • inverter for laptop charging - this plugs into cigarette lighter and is the only AC we need
    • isolator switch
    • split charge relay
    • switch panel
    • fuse box (maybe with built in bus bar?)
    • 12V leisure battery suitable for solar charging
    We need enough solar to power the fridge, vent fan, LED lights and USB sockets but are still researching how many Watts we would need for this.
    At this point we are just making sure we understand how everything connects to each other and that we have grounded all the right components.
    We will then take this feedback, tweak the diagram and begin to research more about our power needs and what to buy.


    Jon and Ellie

    Attached Files

  • #2
    Welcome to the forum!

    I am somewhat new here as well but have done quite a bit of research for making offgrid viable.
    Recently finished doing a stationary setup and now am planning on designing another setup to go mobile.
    I've been looking into van dwelling and it sounds like you are doing the same.
    Though I only plan on using solar during the day, meaning nighttime is for my battery powered items such as netbook, usb light, and smartphone.

    I'm still studying about hooking up power systems to a vehicle, so I cannot comment on the legitimacy of your schematic.
    One thing I might change, as you mentioned, is a fuse block with ground bus to consolidate some of your equipment.
    If haven't found already, Blue Sea Systems may serve as a good resource for you.
    As well as some schematics you can browse through.
    I would send them an email about your schematic, they may provide you with some good feedback.

    I will try to help with your power consumption.
    Your current daily estimate is about 1400wh so the battery you have listed at 230ah will be brought down to 50% in one day.
    If you can get your daily watt hours down to 280wh or 560 wh daily, your battery would last much longer.
    And how are you measuring your usage for loads? Kill-A-Watt?

    Getting a fridge to work with low watt hours is my current challenge for offgrid.
    Which fridge are you looking at using?
    Unless you are able to fit a large fridge in your VW, 700 wh seems to be a lot.
    Most fridges will cycle on and off whenever the fridge needs cooling.
    40 watts may mean that is what it uses while running.
    So if the fridge runs at 40 watts and kicks on for a few minutes several times an hour,
    Then you may use closer to 15-20wh and if running 16 hours, then it will be more like 320 watt hours daily.
    Also, the fridges watt hours can be improved if you do a few things.
    Heavily insulating the outside of it, though only can be done if the condenser is on the outside of the fridge,
    It's sometimes inaccessible on mini fridges, deep freezes, and the 12/24v fridges, the condenser area will be warm if you put your hands on the top and/or sides while it is running.
    To insulate those types, you could put insulation on the inside of the fridge, though you will have to sacrifice storage space.
    During panel/isolator output times, store the cold produced into containers of water, the cold water or ice will act like a thermal battery, thus filling empty space and keeping stable temps.
    Minimize opening it when panels/isolator aren't producing enough to power it.
    Keeping the refrigerated space small.
    If you can keep your cold requirements small enough and you have access to ice (from soda fountains) while on the road, you may try using a few thermoses to store your food.
    With ice in a thermos, many manufacturers claim 6 days under normal conditions.
    I haven't tested it yet, but you might be able to the extend time if you wrap your thermoses up in some well insulated blankets.
    You may get much more than 6 days.
    Also check into dehydrating your foods and potentially making up your own just-add-water-meals.
    I've found grocery stores and gas stations to be my fridges while in civilization.
    Though out in the wilderness, thermos is as of now my go-to for keeping things cold.

    Lighting can be a dark horse for power consumption. By the hour, your lighting may end up using more than your fridge.
    Example, your LED lights strips using 20 wh and your fridge probably using 15-20 wh.
    I'd experiment and see if you can just use a 6 watt led at night/cloudy days.
    You can maximize light from what you've got by using white or light color from your walls, ceiling, and maybe floor.

    If you use an inverter, you will be changing 12v DC to 120v AC then back to something like 19v DC.
    You could instead charge your laptop straight from the 12v battery if you have an adapter/converter.
    This will help avoid the losses from an inverter which requires some extra watts to be on, as well as the inverter efficiency.
    However, I'd recommend having an inverter handy as a backup.
    And you might still use one since the difference may be worth dismissing seeing you are only charging it for 2 hours.
    Also, for your laptop, are you estimating the wattage based on the rated wattage of the laptop power supply?
    My netbook power supply is rated at 45 watts but rarely exceeds 15 watts when charging battery.
    If your laptop actually uses this much wattage while running, I would invest in a netbook or if processing power is critical, then go for a newer laptop.
    Either choice can keep you below 10 watts and potentially below 20 watts for a newer laptop during heavy use.
    I just purchased a netbook and it runs a whopping less-than-5-watts most of the time.
    If we were to compare, at 90wh your current laptop runs for 2 hours at 45 watts whereas that netbook would run 5 watts for 18 hours with the same 90wh.
    That's exceptional, especially when you figure in the battery for the netbook which will give about another 12 hours of runtime.
    I modified the netbook to function like a typical laptop computer meaning I can use it offline and use the programs I normally use.
    If you want to know more about that I can help you, just let me know; I spent a good deal of time digging for "offgrid computer use".
    -->5 watts or less!<--

    If van living, I would also recommend getting a carbon monoxide detector.