This is the third part of our DIY Van Electrical Guide trilogy:

Made with in our van.

Sharing this tool with others is the best way to say thanks if you found it useful. Thanks for supporting us and for keeping this website alive! See you on the road 🙂

Disclosure: This post contains affiliate links, which means that if you click a product link and buy anything from the merchant, we will receive a commission fee. The price you pay remains the same, affiliate link or not.

Share this TOOL:
Facebook
Pinterest
Reddit
short url: faroutride.com/calc
Calculator and diagram workflow:
FarOutRide-Illustration-Cross-Section

Van Electrical Calculator

12V DC
SUMMER
WINTER
LOADName of the appliance. CUR
(A)AVERAGE CURRENT (in amps) drawn during operation. Find this info on Google, product's website, owner's manual, technical sheet.
HRS / DAY
(h)How many HOURS per day this appliance is in operation. It's a guesstimate.
DAILY USAGE
(Ah)CURRENT x HOURS
CUR
(A)AVERAGE CURRENT (in amps) drawn during operation. Find this info on Google, product's website, owner's manual, technical sheet.
HRS / DAY
(h)How many HOURS per day this appliance is in operation. It's a guesstimate.
DAILY USAGE
(Ah)CURRENT x HOURS

TOTAL

120V AC
SUMMER
WINTER
LOADName of the appliance. PWR
(W)MAX POWER (in watts) of the load. Find this info on Google, product's website, owner's manual, technical sheet.
HRS / DAY
(h)How many HOURS per day this appliance is in operation. It's a guesstimate.
DAILY USAGE
(Ah)[(POWER/12) x HOURS] / 0.85
INVThis column is used to size the inverter. Check all the appliances that you plan on using simultaneously. Note that the biggest load is automatically selected by the calculator. PWR
(W)MAX POWER (in watts) of the load. Find this info on Google, product's website, owner's manual, technical sheet.
HRS / DAY
(h)How many HOURS per day this appliance is in operation. It's a guesstimate.
DAILY USAGE
(Ah)[(POWER/12) x HOURS] / 0.85
INVThis column is used to size the inverter. Check all the appliances that you plan on using simultaneously. Note that the biggest load is automatically selected by the calculator.

TOTAL

Battery Type

Your Type


Alternator


1- Size Your Main Components
Use the calculator above
Daily Energy Usage

? Ah

Battery Bank

? Ah

Solar Panels

? W

Solar Charger

?|?

Alternator Charge

? A

Shore Charger

? A

INVERTER

? W

Manual Mode Enabled.
Bold options = automagic values.
2- Size Your Wires, Fuses & Breakers
+ Wire Lengths & Terminals Calculator

Appropriate wire gauge (AWG) varies with length & load and, therefore, is unique to each installation. Our wiring diagram automatically sizes the wire gauge, fuses & breakers to ensure that your own system is safe and performs as it should. Bonus: it also calculates all the wire lengths & terminals that you'll need by type/gauge, which will make STEP 3 (customize your items list) super easy to complete. No other diagram does this!

3- Customize Your Items list

Fill these tables per your wiring diagram:

WIRES LENGTH (FT)

AWG4/03/02/01/01246810121416
RED
BLACK
DUPLEX

TERMINALS QUANTITY

AWG4/03/02/01/01246810/1214/16
#8
#10
1/4
5/16
3/8
Cost EstimateIncludes everything on your Items List, except the 12V & 120V loads (appliances) and Tools. Prices on Amazon change frequently, so our estimate is subject to change.

$X,XXX USD

Items List

The list below defines your entire electrical system. Click on "ADD ITEMS TO AMAZON CART" section-by-section; make sure that all the items are valid (links to Amazon products sometime change, please let us know if that's the case!), and make sure all items are in stock at the moment.

Main
# Item Description Quantity View on Amazon
1 Terminal Fuse Block with Fuse 250A Blue Sea (Catastrophic Fail Safe. Connects directly to battery post.) 1 View
2 System Switch Blue Sea (Main System Switch) 1 View
3 Bus Bar (250A, 4 studs) Blue Sea 2 View
4 Cover for Bus Bar (for 250A 4 studs) Protect the Bus Bar 2 View
5 40A Breaker/Switch, Surface Mount Between Fuse Block and Bus Bar 1 View
6 Fuse Block (12 circuits) Blue Sea (12V Distribution Panel) 1 View
7 Fuses Kit Assorted Fuses (2A 3A 5A 7.5A 10A 15A 20A 25A 30A 35A) 1 View
8 Battery Monitor Victron BMV-712 with BlueTooth 1 View
Hardware
# Item Description Quantity View on Amazon
1 Heat Shrink Butt Connector, Ancor Marine To connect to Loads (75 Pack Kit) 1 View
2 Heat Shrink Disconnect, 10-12 AWG Cable, 1/4″ Tab, Female
To connect to certain loads (i.e. 12V Sockets) , to make “removable” connections (i.e. Fridge, LEDs) and to connect cable of different gauge together (i.e. LED Dimmer) (25 Pack)
1 View
3 Heat Shrink Disconnect, 10-12 AWG Cable, 1/4″ Tab, Male 1 View
4 Heat Shrink Disconnect, 14-16 AWG Cable, 1/4″ Tab, Female 1 View
5 Heat Shrink Disconnect, 14-16 AWG Cable, 1/4″ Tab, Male 1 View
6 Heat Shrink Disconnect, 18-22 AWG Cable, 1/4″ Tab, Male 1 View
7 3M Scotchlok Quick Splice with Gel (14 AWG stranded) We used that to parallel our LED lights (25 Pack) 1 View
8 Heat Shrink Tubing Kit (with adhesive) To protect lug after crimping 1 View
9 Split Loom Tubing, 3/8″ diameter 25 feet To protect wire bundles 1 View
10 Split Loom Tubing, 1/2″ diameter 25 feet To protect wire bundles 1 View
11 Split Loom Tubing, 3/4″ diameter 10 feet To protect wire bundles 1 View
12 Nylon Cable Clamps Kit To secure cable/split-loom to wood 1 View
13 Zip Tie Mount with Adhesive To secure cable/split-loom to metal 1 View
14 Nylon Zip Ties Kit To secure cable/split-loom 1 View
15 Rubber Grommet Kit To protect wire from sharp edge (going through metal hole) 1 View
12V Loads

These are the appliances we personally use in our van:

# Item Quantity Buy Link More Info
1 Maxxair 6200K Roof Fan 1 Amazon Fan Installation
2 LED Ceiling Lights (Dimmable) 3 Amazon
3 PWM Dimmer for LED Lights, 12V, Slider 1 Amazon
4 Blue Sea 12V Socket 4 Amazon Electrical System Guide
5 Shurflo Revolution Water Pump, 3 GPM 1 Amazon
6 ON/OFF Switch for Water Pump 1 Amazon
7 Webasto Air Top 2000 STC Gasoline Heater 1 Amazon Webasto Installation
8 Propex HS2000 Propane Heater 1 Dealers Propex Installation
9 Novakool R5810 Fridge, 12V only 1 Campervan-HQ Fridge Guide
10 Sirocco ii Gimbal Fan, 12V 1 Amazon Sirocco ii Installation / Review
11 Nature’s Head Composting Toilet 1 Amazon Toilet Installation
12 Propane Solenoid Shutoff Valve 1 Amazon
13 ON/OFF Switch for Propane Solenoid 1 Amazon
Tools

These are essential to build your electrical system. Do NOT cheap out on tools (e.g. using pliers to crimp), or you'll compromise the performance and safety of your system.

#ItemDescriptionQTYView on Amazon
1Cable Cutter (up to 4/0 AWG)For large gauge cables1View
2Wire & Cable Cutter (2/0 – 22 AWG)Nothing to add!1View
3Wire & Cable Stripper (4/0 – 20 AWG)Nothing to add!1View
4Hydraulic Crimping Tool (4/0 – 10 AWG)Provides adequate, repeatable results for larger gauge lugs.1View
5Crimping Tool, Single-Crimp (8 – 22 AWG)Single-Crimp should be used with Heat Shrink connectors to prevent tearing the insulation and loosening the watertight connection (corrosion prevention)1View
6Heat Gun for Heat Shrink Connectors1800W, Variable Temperature Control1View
7Digital Multimeter (Voltage, Current, Continuity, Resistance)You don’t need it until you need it! Your friend when you need to troubleshoot…1View

Want More?


WE’RE JUST GETTING STARTED.

Stay in touch!


JOIN 40,000+ FOLLOWERS VIA FACEBOOK, INSTAGRAM OR YOUTUBE:

About us


NICE TO MEET YOU.

About-Us-Narrow

Hello! We’re Isabelle and Antoine 🙂 In 2017, we sold our house (and everything in it), quit our engineering careers, and moved into our self-built campervan. Every day is an opportunity for a new adventure... We’re chasing our dreams, and hopefully it inspires others to do the same!

Heads Up: Exclusive Deals!


Thanks to all of you, we managed to negociate group discount on these. Strength in numbers!

156 thoughts on “Van Electrical Calculator”

  1. Thanks for the wonderful resources. We’ve been following along for a couple years while we waited for a van and are finally building!

    I had a question about fuses: elsewhere on the website you mentioned to avoid generic fuses and breakers from Amazon, but on this page it appears to link to a pretty generic brand for fuses. Have you used these fuses or are you fairly confident in their reliability?

    I am trying to figure out whether to get these or to pay extra $$ for Ancor ATO fuses 🙂

    Reply
    • Our intention for ALL the BREAKERS is to link to BlueSea breakers (or equivalent quality).
      For small blade fuses (e.g. automotive fuses), it’s fine to use more generic brand.

      Sometimes Amazon listings change and it’s hard to keep track, please report it to us if that is the case!
      Thank you 🙂

      Reply
      • Thank you, that makes sense! I was just talking about the blade fuses; glad to know the more generic brand is probably ok. Though I did find some nice BlueSea blade fuses that light up when they burn out, I might splurge on those anyway just for fun:)

        Reply
  2. This series is so helpful, thank you!
    I’m a little confused though with some of the math.
    If I have a 700W appliance, why am I supposed to divide by 12V and not 120V if it’s a 120V?
    Thank you!

    Reply
  3. I continue to be amazed by the depth of detail you provide in your tutorials. I’ve searched your prior comments and have not found an answer to my build dilemma: I have a Jackery 1000 and I’ve read your comments regarding it’s potential in a van build. I used it this past summer with no issues but I am now doing a rebuild in which I want to add an addition Battle Born 1000 ah battery to handle most of the 12-volt load and the Jackery for my very limited AC needs. The question is how to wire in charging from the solar to both batteries. My understanding is that they can be charged simultaneously with the two charging managers (one in the Jackery and one dedicated to the BB) managing each charging level. If so, that’s straight forward. If not, I’d like your suggestions.

    Related is the 2020 Ford Transit’s 120 VAC power supply located next to the emergency brake. Can I also connect this to the BB battery via an AC-DC converter and leave it connected permanently?

    Thank you in advance for you reply.
    Larry

    Reply

Leave a Comment