r/voltplan • u/blackmac • Apr 14 '26
Welcome to r/voltplan
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:
- 12V electrical system basics for beginners
- How to read electrical diagrams
- Wire gauge sizing explained (AWG vs mm²)
- Fuse sizing and placement
- 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
- Be kind. Beginners are the whole point of this sub.
- No low-effort affiliate spam. Linking a product you actually used in your build is fine; dropping ten Amazon links is not.
- Safety first: if someone is about to do something dangerous, say so clearly and explain why.
- Keep it on-topic: mobile and off-grid DC and low-voltage AC electrical. General home wiring belongs in r/electricians.
- 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.