Solar & Battery Electrical Calculator for Campervans | VanPowerCalc

Q: Which Ford Transit wheelbase for a van conversion?

148" extended wheelbase (350 HD) is the gold standard — enough length for a bed, kitchen, and bathroom without sacrificing driving maneuverability. The 130" works for minimalist builds. The 178" extended is rarely needed and harder to park.

Q: Should I order a cargo or passenger Transit?

Cargo van, every time. You're removing the interior anyway. Cargo spec saves $2,000-5,000 and you don't deal with removing passenger windows, seats, and trim. Exception: if you need windows for natural light and don't want to cut the body yourself.

Q: Is the dual battery prep package worth it?

Absolutely. It pre-runs heavy-gauge cable from the engine bay to the rear — saving you a full day of routing cable through the chassis. At $200-400 factory cost, it's the best value option for any conversion.

Q: Diesel or gas engine for van life?

Diesel (2.0L) for European travel and long-distance touring — better fuel economy and easier to find diesel in Europe. Gas V6 (3.5L EcoBoost) for US-focused builds — cheaper maintenance, more power, and US diesel prices aren't always competitive.

Q: What factory options should I skip?

Skip: premium interior trim (you're gutting it), built-in navigation (phone does better), rear window wiper (covered by your build), and any rear interior options. Keep: cruise control, power mirrors, upgraded alternator, dual battery prep.

Leo

Fact-checked on Apr 5, 2026

Ordering a 2026 Ford Transit for Conversion: The Options That Matter

Options that matter for a campervan build: battery prep, rear camera delete, 148" WB. What to spec and what to skip.

4 min read

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Your electrical appliances

Quick Add

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Daily Total

0

WH / Day

Tap a preset above to start

System Config

System Voltage

Average Sun Hours

VANPOWERCALC.COMYOUR ENERGY PROFILE

YOUR ENERGY PROFILE.

This document contains the sizing of your future electrical installation, calculated based on your appliances.

Minimum Daily Consumption

0 WH / DAY

Inventory:

SYSTEM SIZINGPage 2

Battery

To guarantee 0WH without damaging your bank (80% max discharge):

0 AH

LiFePO4 12V

Solar

Minimum power required to recharge your consumption:

0 W

via MPPT

220V AC

Maximum power (with 25% safety margin).

0 W

No Need

Safety & CablingPage 3

12V Cable Sizing Guide

Use this professional reference table to select the correct gauge (mm²) for your cables. For 12V in a van, the maximum tolerated voltage drop is 3%. Always use multi-stranded flexible automotive wire.

Current (A)	Round trip < 2m	Round trip 4m	Round trip 6m
5A (LEDs, USB)	1.5 mm²	2.5 mm²	4 mm²
10A (Fridge, Pump)	2.5 mm²	4 mm²	6 mm²
20A (Heater)	4 mm²	10 mm²	10 mm²
50A (DC/DC Booster)	10 mm²	16 mm²	25 mm²
100A (Inverter)	25 mm²	35 mm²	50 mm²

Fuse Sizing

The fuse protects the wire, not the appliance. Always place it as close to the power source as possible (battery or busbar).

Wire 1.5 mm² → Max fuse 10A
Wire 2.5 mm² → Max fuse 20A
Wire 4 mm² → Max fuse 30A
Wire 6 mm² → Max fuse 40A
Wire 10 mm² → Max fuse 60A

SCHÉMA ÉLECTRIQUE

PANNEAUX SOLAIRES

0W

RÉGULATEUR MPPT

BATTERIE AUXILIAIRE

0 Ah

Lithium LiFePO4

FUSIBLE

BOÎTE À FUSIBLES 12V

Pompe, Leds, Frigo...

CONVERTISSEUR 220V

NON REQUI

PRO GEARPage 4

SHOPPING LIST

Where to find this equipment? Here is the community-approved selection.

12V 6-way Fuse Box

Mandatory protection

Digital Multimeter

Test your connections

Heavy Duty Crimping Tool

For perfect lugs

Heat Shrink Tubing

Insulation and safety

GENERATED BY VANPOWERCALC.COM

If you're ordering a new Transit specifically for a van build, the options list matters more than the price. Some $200 factory options save you $1,000+ in aftermarket work. Others are a waste of money because you're ripping them out anyway.

The must-have options: Dual battery/upfitter prep package — pre-runs heavy-gauge cable from alternator to rear. Saves $300+ in cable and a full day of labor. 148" wheelbase, high roof — the only configuration that's comfortable to stand in and sleep lengthwise. Rear camera delete (if available) — you're removing the factory interior anyway. Skip: cruise control is worth keeping, the factory stereo is fine, and side windows are personal preference.

12V cable sizing guide for RVs — vanpowercalc.com

Expert tip

Order the highest-output alternator option (200A+ if available). The price difference is $100-200 at the factory but $800+ for an aftermarket alternator upgrade. More alternator headroom means faster DC-DC charging without stress.

Example calculation for your setup

Results based on a typical use case

Appliance	Power	Usage/day	Wh/day
Compression fridge	45W	24h	1080
LED lighting	20W	4h	80
Water pump	30W	0.5h	15
Phone charging	15W	2h	30
Daily consumption			1205 Wh

Recommended LiFePO4 battery

151 Ah

(80% depth of discharge)

Recommended AGM battery

241 Ah

(50% depth of discharge)

Recommended solar panels

402 Wc

4h average sun hours

Recommended inverter

No 220V appliances — no inverter needed

Adjust these values with the calculator below

About this tool

The 2026 Transit comes with Ford's 2.0L EcoBlue diesel (EU) or 3.5L EcoBoost V6 (US). Both have smart alternators — factor a DC-DC charger into your build cost regardless of engine choice. The diesel is more efficient for long-distance travel; the gas V6 is cheaper to maintain in the US. One thing Ford changed for 2026: the electrical pre-wire option now includes a 30A relay-ready circuit to the rear. This doesn't replace a DC-DC charger (it's still relay-based, not voltage-boosted) but it provides the wire routing you need. Just remove the relay and wire in your DC-DC charger using the same cable run. If you're converting for full-time living, order the most basic interior trim. You're removing the floor, walls, and ceiling anyway. Cargo van spec saves $2,000-5,000 over passenger van trim. Keep the front seats nice — you're sitting in them daily.

ByLeo—Electrical Engineer & VASP Builder

Published March 31, 2026

Frequently asked questions

Which Ford Transit wheelbase for a van conversion?▼

148" extended wheelbase (350 HD) is the gold standard — enough length for a bed, kitchen, and bathroom without sacrificing driving maneuverability. The 130" works for minimalist builds. The 178" extended is rarely needed and harder to park.

Should I order a cargo or passenger Transit?▼

Cargo van, every time. You're removing the interior anyway. Cargo spec saves $2,000-5,000 and you don't deal with removing passenger windows, seats, and trim. Exception: if you need windows for natural light and don't want to cut the body yourself.

Is the dual battery prep package worth it?▼

Absolutely. It pre-runs heavy-gauge cable from the engine bay to the rear — saving you a full day of routing cable through the chassis. At $200-400 factory cost, it's the best value option for any conversion.

Diesel or gas engine for van life?▼

Diesel (2.0L) for European travel and long-distance touring — better fuel economy and easier to find diesel in Europe. Gas V6 (3.5L EcoBoost) for US-focused builds — cheaper maintenance, more power, and US diesel prices aren't always competitive.

What factory options should I skip?▼

Skip: premium interior trim (you're gutting it), built-in navigation (phone does better), rear window wiper (covered by your build), and any rear interior options. Keep: cruise control, power mirrors, upgraded alternator, dual battery prep.

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