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
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
Comparison table
| Profile | Usage/day | LiFePO4 bank | Solar needed |
|---|---|---|---|
| Weekend warrior | 500 Wh | 125Ah → 150Ah | 150-200W |
| Remote worker | 1,000 Wh | 250Ah → 300Ah | 300-400W |
| Off-grid explorer | 1,400 Wh | 350Ah → 400Ah | 400-500W |
| Full-timer comfort | 1,800 Wh | 450Ah → 500Ah | 600-700W |
About this tool
How to Size Your Off-Grid Van Battery Bank
Your battery bank is the heart of your van electrical system. Too small and you're constantly anxious about power; too large and you've wasted money on capacity you never use. Here's how to size it correctly.
The Correct Sizing Formula
Required battery capacity (Ah) = (Daily consumption in Wh × Days of autonomy) ÷ (Battery voltage × DoD)
- DoD = Depth of Discharge (how much you can safely discharge): 80% for LiFePO4, 50% for AGM
- Battery voltage: typically 12V for vans under 400Ah, 24V for larger systems
Example: 800Wh/day × 3 days autonomy ÷ (12V × 0.80 DoD) = 250Ah LiFePO4
Battery Technologies Compared
| Technology | DoD | Cycle Life | Cost/kWh | Weight/kWh | Best For |
|---|---|---|---|---|---|
| AGM | 50% | 300-500 | $200-350 | 30-40 kg | Budget builds |
| GEL | 50% | 500-800 | $300-450 | 28-35 kg | Long life budget |
| LiFePO4 | 80% | 3,000-5,000 | $400-700 | 10-15 kg | Full-time van life |
| LifeP04 (DIY cells) | 90% | 5,000+ | $200-350 | 8-12 kg | DIY experienced builders |
Autonomy by Battery Size (LiFePO4)
| Battery Size | Usable Energy | Autonomy (600Wh/day) | Autonomy (1,200Wh/day) |
|---|---|---|---|
| 100Ah (12V) | 960Wh | ~1.6 days | ~0.8 days |
| 200Ah (12V) | 1,920Wh | ~3.2 days | ~1.6 days |
| 300Ah (12V) | 2,880Wh | ~4.8 days | ~2.4 days |
| 400Ah (12V) | 3,840Wh | ~6.4 days | ~3.2 days |
Balancing Battery Size with Solar
A battery bank without adequate solar is just a slow countdown to empty. The general rule: 1Ah of LiFePO4 storage needs 2-3W of solar for summer self-sufficiency (4-5h peak sun hours). For a 200Ah LiFePO4: 200 × 2.5 = 500W of solar in summer conditions.
In winter (1.5-2h peak sun): the same 500W produces only 600-700Wh/day — roughly 1/3 of summer. Add DC-DC charging via alternator to compensate.
Series vs Parallel: Wiring Your Battery Bank
- 12V budget builds (< 200Ah): Single 12V battery or 2× batteries in parallel
- 12V large builds (200-400Ah): Multiple 100-200Ah LiFePO4 in parallel, or purchase a single 200-400Ah unit
- 24V systems (> 400Ah equivalent): Pair 12V batteries in series for 24V → reduces wire gauge requirements significantly
Expert tip: For van life, LiFePO4 is always worth the premium over AGM. AGM's 50% DoD means you need double the Ah rating to get the same usable energy — at that point, LiFePO4 is the same or cheaper when you factor in the 10× longer lifespan.