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A diesel heater uses 100Wh of electricity per night. An electric heater uses 3,000-6,000Wh. That single fact decides the debate for 95% of van builds. Diesel wins so overwhelmingly that electric heating only makes sense in very specific circumstances.
The numbers: a diesel heater (Webasto, Espar, or Chinese clone) burns 0.1-0.3L of diesel per hour at a cost of ~$0.15-0.45/hour, while drawing only 8-12W electrically. An 8-hour night: ~1L diesel ($1.50-2.00) + 100Wh electrical. A 1,500W electric heater for the same 8 hours: 12,000Wh = 1,000Ah at 12V. You'd need a 1,200Ah battery bank just for one night of heating. That's $4,000+ in batteries.
⚡ Expert tip
Run your diesel heater for 30 minutes at high setting when you first turn it on, then switch to low. Short cycles with frequent restarts burn carbon on the glow plug and heat exchanger. Long, steady runs at low settings produce cleaner combustion and extend heater life by years.
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
126 Ah
(80% depth of discharge)
Recommended AGM battery
201 Ah
(50% depth of discharge)
Recommended solar panels
302 Wc
4h average sun hours
Recommended inverter
No 220V appliances — no inverter needed
Adjust these values with the calculator below
VANPOWERCALC PROYOUR 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
REGULATEUR MPPT
BATTERIE AUXILIAIRE
0 Ah
Lithium LiFePO4
FUSIBLE
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 PRO - UNLIMITED.
About this tool
The only scenarios where electric heating works in a van: 1) Shore power — plugged into a campsite or house outlet, electric heat costs pennies and makes zero noise. A small 500W ceramic heater maintains a van above freezing for $0.15/night in electricity. 2) Short trips in mild weather — a 200W heated blanket draws only 17Ah/night, enough to take the edge off in 5-10°C weather without a diesel heater install. 3) Diesel heater supplement — a 12V heated mattress pad (40-60W) combined with a diesel heater on low setting maximizes comfort while minimizing fuel and electrical use. The diesel heater's biggest downside is installation complexity: fuel line from the tank, exhaust pipe, combustion air intake, electrical wiring, and controller mounting. It's a full day project. But once installed, you have essentially unlimited heating for the cost of diesel — your battery barely notices it.
Frequently asked questions
How much electricity does a diesel heater use?▼
8-12W during normal operation (fan + controller), with a 60-70W spike for 2-3 minutes at startup (glow plug). An 8-hour overnight run uses about 100Wh total — roughly 8Ah from a 12V battery. That's 4% of a 200Ah bank. Negligible.
Can I heat a van with just battery power?▼
Not practically with resistive heating. A 1,500W heater drains a 200Ah battery in ~1.5 hours. A heated blanket (200W) lasts ~10 hours on 200Ah — usable in mild weather but not in freezing conditions. Diesel is the only viable standalone heating solution for cold weather.
Webasto vs Chinese diesel heater?▼
Webasto/Espar: $700-1,200, quieter, more reliable, better cold-start performance, proper certification. Chinese (Vevor, generic): $100-180, louder, higher failure rate, but functionally identical technology. For full-time winter vanlife: Webasto. For occasional use: Chinese is fine.
How much does a diesel heater cost to run?▼
0.1-0.3L diesel per hour = $0.15-0.45/hour. An 8-hour winter night costs $1.50-3.00 in diesel plus ~8 cents in electricity. Compare to a propane heater at $0.30-0.50/hour or electric at $1.50-3.00/hour (on shore power) or impossible on battery.
Can I install a diesel heater myself?▼
Yes, with moderate mechanical ability. It requires: drilling a hole in the floor for exhaust and combustion air, running a fuel line from the tank (or auxiliary tank), electrical connections (12V supply, controller), and routing the hot air duct. Budget a full day. Watch at least 3 YouTube install videos for your specific van model before starting.