YOUR ENERGY PROFILE.
This document contains the sizing of your future electrical installation, calculated based on your appliances.
Inventory:
Battery
To guarantee 0WH without damaging your bank (80% max discharge):
Solar
Minimum power required to recharge your consumption:
220V AC
Maximum power (with 25% safety margin).
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
REGULATEUR MPPT
BATTERIE AUXILIAIRE
0 Ah
Lithium LiFePO4
BOÎTE À FUSIBLES 12V
Pompe, Leds, Frigo...
CONVERTISSEUR 220V
NON REQUI
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Comparison table
| Grounding method | Use case | Difficulty | Risk |
|---|---|---|---|
| Chassis ground (single-point) | 12V system standard | Easy | Low if done correctly |
| Star ground (battery negative) | Best practice | Medium | Very low |
| Series ground loops | Common mistake | — | High — avoid |
| Bonding + ground bar | Dual-battery setups | Medium | Very low |
About this tool
Two Types of Grounds in a Van Build
Chassis ground (negative from battery to van body metal) and system ground (negative distribution point for all 12V accessories) are often confused. Chassis ground connects your battery negative to the van's metal frame — this is required for engine electrical compatibility and for safety. System ground is your negative bus bar or distribution block where appliance negatives terminate. Both need clean metal-to-metal contact.
Where to Ground: The Right and Wrong Points
The right chassis ground point is always bare, unpainted metal with at least 8 AWG cable (4 AWG recommended for systems over 60A). Remove paint with a wire brush, use a star washer to bite into the metal, and apply dielectric grease after assembly. Wrong points: seat belt mounts (structural, don't modify), thin sheet metal panels (flex and corrode), pre-existing bolts without paint removal. The single best grounding point in a Mercedes Sprinter is the factory chassis ground bolt near the battery — it's already designed for high-current ground and is made of proper steel.
Ground Loops and Corrosion
Running 12V appliance grounds back to the battery negative directly (instead of to a central negative bus bar) creates multiple ground paths of different lengths — called a ground loop. Ground loops cause mysterious interference (radio noise, display flickering) and make finding faults a nightmare. The correct approach: one central negative bus bar near the battery, all appliance negatives go there, one thick cable connects the bus bar to the battery negative terminal.
Testing Your Ground System
Use a multimeter in DC voltage mode. With your system under load (fridge + lights running), measure from battery negative terminal to each appliance's negative terminal. Voltage drop should be under 0.3V. More than that and you have a resistance problem in that ground path. Repeat for chassis ground: battery negative to a chassis bolt should show less than 0.1V.
Dissimilar Metal Corrosion in Vans
Mixing aluminum and copper without protection causes galvanic corrosion — the junction turns into a battery that slowly dissolves one metal. Always use tinned copper wire (not bare copper) in vans, especially near rear doors where humidity enters. Use aluminum-rated connectors for aluminum bus bars. Apply Penetrox or No-Ox-Id paste at any copper-to-aluminum junction.