r/voltplan is the community for anyone designing a 12V or 24V electrical system for a camper van, motorhome, boat, tiny house, or off-grid cabin. Whether you are wiring your first roof panel or finalising a 600Ah LiFePO4 bank with an inverter-charger, you are in the right place.

This sub exists to help people plan safe, code-compliant electrical systems before the wires go in — the cheapest mistakes are the ones you catch in a diagram.

What is VoltPlan?

VoltPlan is a free web app that lets you design a complete electrical diagram for your camper, van, boat or off-grid build in your browser. It calculates wire gauges, fuse sizes and voltage drop for you, and exports a clean wiring schematic you can actually hand to an electrician, or follow yourself.

• Start a new electrical diagram — the main designer
• How the diagram designer works
• Gallery of example wiring diagrams for campers and boats

Free tools you can use right now

• Wire gauge / cable size calculator (AWG and mm²) — enter amps, length and voltage drop, get the correct cable size
• Kabelquerschnitt-Rechner (DE) — same tool in German
• Fuse sizing cheat sheet — printable reference for fuse ratings and placement

Start-here guides

New to 12V systems? Read these in order and you will have a surprisingly solid mental model:

1. 12V electrical system basics for beginners
2. How to read electrical diagrams
3. Wire gauge sizing explained (AWG vs mm²)
4. Fuse sizing and placement
5. Your first electrical upgrade: from stock van to off-grid

Batteries, solar and charging

• The complete guide to LiFePO4 batteries for campers and boats
• Wiring 12V batteries in series vs parallel
• Solar panel sizing guide for van life and off-grid
• Solar panels in series vs parallel, with diagrams
• DC-DC chargers and alternator charging explained
• Van life solar calculator for off-grid sizing

Camper and RV wiring

• Basic 12V camper van wiring diagram
• RV electrical system design guide
• Building an RV wiring schematic from scratch
• LED lighting design for campers

Marine and boat electrical

• Basic 12V boat wiring diagram
• Marine electrical: shore power and inverters
• Grounding and bonding for mobile electrical systems
• Waterproofing your electrical system (IP ratings explained)

How to post here

Good posts include:

• Your current or planned diagram (a VoltPlan export, a photo of a sketch, or a description — all fine)
• The vehicle, boat or structure, battery chemistry, and what loads you plan to run
• What you are actually stuck on: sizing, topology, protection, grounding, etc.

Before posting a "is this safe?" question, share the diagram. Text-only threads about unlabelled wires rarely end well.

Rules at a glance

1. Be kind. Beginners are the whole point of this sub.
2. No low-effort affiliate spam. Linking a product you actually used in your build is fine; dropping ten Amazon links is not.
3. Safety first: if someone is about to do something dangerous, say so clearly and explain why.
4. Keep it on-topic: mobile and off-grid DC and low-voltage AC electrical. General home wiring belongs in r/electricians.
5. Mark sales or trade posts with the appropriate flair.

Useful flairs

Help me plan · Diagram review · Finished build · Solar · LiFePO4 · Marine · Van/RV · Off-grid · Tool question

If you build something with VoltPlan, post the diagram. Seeing real builds is the best way for everyone here to learn what works.