162 thoughts on “Van Electrical Calculator”

1. Hi Antoine,

   I live in Australia. (230V AC) with metric sizes for cables etc. Also I am starting a renovation on a European vehicle which is a 2016 Renault Master MWB, H2/L2.
   Is the builder’s package suitable for me or is it strictly for the 3 vehicles mentioned above? Which of the packages is suitable for my situation?
   Many thanks and kind regards,

   Jim

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2. I’m interested in buying your wiring diagram.
   Could you please clarify:
   Is the purchase downloadable file(s) such that they are reconfigurable?
   Example, I buy and download, and (I’m assuming here) configure the inputs ((example: 4′ run)), but upon doing the build I realized it needs to change to 10′, which might change the wire size. Can I then go back in and change the input where it’ll update and tell me the correct wire size to use?
   In advance, thank you.
   Sidebar, AWESOME content….by far, the most thorough anywhere.

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   • Yes, you can save the PDF anytime, so it’ll always “remember” your inputs. You can re-open the diagram later and modify it as needed.
     Hope this helps!

     Thanks for the kind words and support, it means a lot.
     Antoine 🙂

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3. I bought a van that was setup exactly using your standard diagram without any inverter and a 100 AGM battery.

   I’d like to upgrade the battery bank and add an inverter without switching everything out but don’t want to do something that will break the current setup. If I installed 400-500 Amp Hours of LiOn batteries and added a 3000 watt inverter would I have problems?

   I see that it says not to use any appliance over 1650 watts on the standard diagram. Would I still need to stick to that limitation if I added a larger inverter? I generally won’t have more than that running but there may be times it would be over 2000 watts (split between 2 appliances) for a short time.

   If I need to swap the cables and bus out I can but I’m hoping to keep it as simple as possible.

   Thanks for your help, I’m learning a lot from the tutorials but still trying to wrap my head around it all.

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   • Hi,
     Unfortunately it is more complicated than just upgrading the battery bank and the inverter.
     You’ll also have to increase the gauge of most of the cables (and fuse), make sure the components (bus bars, switches, etc) are rated for higher current.

     I’d recommend using our High-Power diagram (and calculator) to prevent any mistake. Please contact us (https://faroutride.com/about-us/contact-us/) with your original order number (or email) and we can give you access to the diagram!

     Cheers,
     Antoine

     Reply

4. Hi guys – Thanks for the content! We bought your basic wiring diagram, and it (plus the items list and calculators) have been a huge help. Our loads and items list is very similar to yours, and includes one 120V AC wall outlet connected to the inverter buy a plug-in cord as recommended. There’s no “electrical box” behind the outlet though, and I was curious if you used one or not? They are plastic boxes that usually fit inside the wall behind an outlet when installed in a house. These aren’t recommended for any of the outlets, but just wanted to ask if an electrical box is needed behind the 120V outlet or 12V sockets? Thanks!

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5. What if I have more than 12 12 volt loads? Could I still make the one 12 load blue sea fuse block work?
   Thanks so much for your hard work building this site.
   -Ben

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6. Quick question – I’m thinking about buying access to your wiring diagram tool, but my battery is 24v and uses a voltage converter to step down for the 12v system. Will your tool be able to accommodate this?

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7. Hello Isabelle and Antoine,
   I feel dumb because I went through your pages and comments, somehow I didn’t find anyone with the same question: how do you get to use a fuse of175 amp for the 1000w inverter? I though I would just have to calculate W/v, so somewhere around 90amp.

   Thank you for your content, you are amazing. have a great day

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   • You also have to account for efficiency, add a “buffer” and take into account temperature ampacity de-rating, so it’s more like W/V/efficiency x 1.4.
     But in the end we follow Samlex Owner’s Manual, it has the fuse size recommendation in it 🙂

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     • This is somewhat off-topic but I’m having trouble sizing our bus bar. We have a 60a b2b, a 1000w continuous inverter, 50a mppt and blue sea fuse block withb100a max load. Would 250a be enough? I’m thinking 300 wouldn’t be enough but based on your diagram and that you’re using a 250a busbar in this setup I must be missing something in how to calculate. Thanks for your awesome guide.

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       • Looks like 250A is the way to go with what you described 🙂
         You can follow these best practices when making connections: https://faroutride.com/electrical-system/#best-practices-distribution

         regards, antoine

         Reply

8. What a great site. I come here a lot and have shared it with others. It’s amazing what you’ve done. I’d like to send you some coffee to try. It’s super smooth dark roast. THANKS for all the guidance.

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   • Haha THANK YOU!
     🙂

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9. Your Wiring Diagram – High Power is excellent! I couldn’t approach building out my van without it. Regarding the OEM cable for the heater, what is the size and length of that cable? And for all cables, I have assumed the length of the cable used to determine wire size is the physical length of the cable. But I have encountered installation manuals that use twice the length of the physical cable to account for the electrons traveling through the positive wire and back through the negative wire. The Espar M2 D4L Heater Manual is one example which uses twice the length of the physical cable resulting in a wire size of a whopping 6mm. Are there any component wires in your diagram that use twice the length of the physical cable to determine the wire size? Thanks.

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   • The length used to calculate voltage drop is indeed always positive + negative (twice physical length). In the wiring diagram 12V DC load section you have to enter the one-way length because and the built-in calculator multiply the length by 2 (per tutorial page 8 bullet 3). In our wire gauge calculator you have to enter the return-length (positive + negative per note between “Wire Length” and input case). And then we also talk about that in our Electrical System Guide under section “7.1. Wire Diameter”

     Cheers,
     Antoine

     Reply

10. Thanks so much for everything you guys do for the community! My van wouldn’t be built without you! Quick question about the Victron solar chargers…the extra ground point on the side… did you do a second wire to the negative bus bar since the bus bar is grounded to the van as well?

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    • It’s not mandatory to connect the ground point on the side in a mobile application, but it doesn’t hurt either to connect it to the negative bus bar!
      cheers,
      Antoine

      Reply

11. Thanks for your efforts, I would say that a very important addition to the resources you’ve provided is to discuss and recommend higher voltage battery banks.

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    • It seems more and more people are leaning toward it. My understanding is that a higher voltage battery can provide the following benefits:
      – Use smaller cables (cost saving). Especially useful for system with inverter over 3000W (which requires massive cables).
      – Use twice the solar power for a given MPPT controller.
      – Slightly better conversion efficiency to 120V AC.

      Anything else I’m missing? Cheers!

      Reply

12. … U GUYS ROOOOOOOOOOOOCK !!!!!!!!!!!!!!!!
    … BEST CAMPER SITE EVER !!!
    … KNOWLEDGE, LOVE, PASSION AND DESIGN.
    … THANK U SO MUCH.

    TOM

    Reply

13. Hi, thanks so much for publishing this calculator! We found it really useful when creating the electrical system for our van. We have now lived in the van for a few months and the electrical system is perfect for us!
    We have linked this post to our blog in the hopes that others find this useful tool too! Thanks for all the helpful info.

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    • Glad we could help, thanks for sharing!!

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14. I used your calculator to determine battery and inverter sizes. I’ve noticed that even if I only need the inverter for, say a low draw device like a laptop or TV, the calculator recommends a 1000 W inverter. Is there a reason for this? I think one can purchase a 700 W inverter from Renogy . Maybe they’re the only ones who make such a “small” inverter and since it’s in your budget category, it’s not factored into the calculator??

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    • Even if you need less than 1000W inverter initially, I’d still recommend 1000W to make it “future proof”; chances are that you’ll need more than 700W eventually…

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15. Hello there! The calculator is recommending a 600 Ah Battery Bank for me, but the High Power Wiring Diagram will only let me select up to 4 batteries (I got 6 100Ah Lithium batteries). Do I need to make any changes, or just add in the extra 2?

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    • I should have kept reading. I see my answer in the tutorial!!

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    • You can go with 6 without any change to the diagram! 🙂

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16. Thank you guys so much for all the information you provide. I am not looking to build out my van to the degree you have, but all the information and attention to detail is greatly appreciated. I bought a barebones Sprinter 4×4 new, already had a few issues with it. Luckily it was all fixed under warranty. But i think people like me love these Sprinters for the reason they’ve been making them for over 25 years. The ergonomics are incredible and it’s the most comfortable long distance vehicle I have owned. But like you state, dealerships are far in between and mechanics with the knowledge how to work on these vehicles are hard to come by. The Transit seems like a great alternative. Plus the back seats actually recline and fold away. Hopefully my van keeps going strong and I am looking forward to building it out a bit. It’s my daily driver but looking into a modular build so I can easily use it for the hauling and work I do, and adventures or living when possibly $h!+ hits the fan.
    I have forwarded your site to friends of mine. One who is looking to live in his van for a while and a few other van owners I know.
    Thank you again for this great detailed website. I know we all greatly appreciate the work you have done and shared with all of us.
    -Bigfoot

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17. Is there a way to chance the 120VAC to 240VAC for UK customers?

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    • Not at the moment, sorry!
      It’s on the to-do list…

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18. Hi hi!

    I just wanted to thank You both for provided as much detail as you do. It has made a tremendously large project more accessible for first timers. THANK YOU!

    I wanted to note that in my wiring diagram, the solar wire length does not sum in the field at the bottom for me. I had 15ft selected for both + & – and the sum does not reflect that. Forgive me if this is just something that I’m doing wrong and there is an easy answer.

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    • Sorry for the late response. We recommend to use those wires with MC4 connectors (in SOLAR section): https://amzn.to/3wLTDWc
      So they are not part of the calculation for “regular” wire.

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19. Hey you two,
    Alaskan here- I am building a van and use your site some or references on things I don’t do much (my solar is out of date, lithium batteries…), but a lot of it is boat similar, and there I am very current.
    So, if you need a warm dry place to do some repairs while in AK, I have a well tooled shop you can park in, gratis (for your great website).
    We are also Alaska wise, if we can help some with the lay of the land!
    chaninak@hotmail.com

    Reply

20. Hey guys,

    Great resource. So much info on here. Thank you for all the time and work you put into the site.

    I pulled the trigger and purchased the diagram, and although it is nice being able to see the details up close, there are a few discrepancies that are making things complicated and seem conflicting. The diagram shows 2/0 wire for the main battery connections, while your shopping list shows 4/0. I was wondering if this was a dynamic field that might adjust with length, but it doesn’t appear to be. Would be great to update the diagram or the shopping list to be congruent.

    Also, many folks are using the Renogy RBC50D1S (DC-DC with MPPT, essentially charge controller and DC-DC in one box), and this has different wiring reqs and fusing requirements. I know it is hard to keep up with all the different and new technologies that are out there, and to build something that will work for many different systems, but I guess for $40, I was expecting a bit more from the diagram than what you already share for free on the site (which is a LOT!). Thanks!

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    • Hi,
      The wire gauge size depends on the inverter you select (4/0 is for 3000W inverter); so if you select a different inverter in the calculator VS the wiring diagram, they won’t match.

      Everyone want to customize their system differently… It’s impossible for us to cover all the products and configurations imaginable. So we selected what we think it’s the best for most people (and for us).

      We know our diagram(s) are not perfect, but thanks for buying it anyway to support all the free stuff we have on our website.

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    • The wire gauge you need varies with how much power you plan to pull, and the length of the run. When in doubt, go bigger. It’s more expensive, but you’ll lose less to resistance and if you upgrade in the future, your battery wires will already be nice and big.

      Reply