Running a Microwave in a Campervan: Power Requirements
A microwave is one of the most frequently asked about appliances in campervan electrical planning — and one of the trickiest to run off a battery system. The key issue is not the power output printed on the front of the microwave. It is the actual power it draws from the mains — which is typically 40-60% higher.
This guide explains the real power requirements, what inverter and battery you need, and whether it is actually worth doing.
For the broader picture of running 230V appliances from your leisure battery, see our inverter sizing guide and how to wire an inverter guide.
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Microwave Power: The Number That Matters
The wattage printed on a microwave — "800W", "900W", "1000W" — is the cooking output power, not the electrical input power.
A microwave with 800W cooking output typically draws 1,200-1,400W from the mains. This is because the magnetron (the component that generates microwaves) is only 60-70% efficient.
Actual mains power draw by cooking output rating:
| Cooking Output | Actual Input Power | DC Current at 12V |
|---|---|---|
| 700W cooking | ~1,100W input | ~108A |
| 800W cooking | ~1,200-1,300W input | ~118-127A |
| 900W cooking | ~1,350-1,450W input | ~132-142A |
| 1000W cooking | ~1,500-1,600W input | ~147-157A |
This means even a compact 700W microwave needs an inverter rated for at least 1,500W, and demands 100A+ from your battery during use.
What Inverter Do You Need?
Minimum inverter size: 1,500W for a 700W microwave. Recommended: 2,000W or larger to give headroom.
Must be pure sine wave. Microwave magnetrons are sensitive to waveform quality. A modified sine wave inverter will cause the microwave to run inefficiently, generate more heat, produce unusual sounds, and potentially cause premature failure. Never run a microwave on modified sine wave. See our pure sine vs modified sine guide.
Battery Drain
Microwaves are typically used for short durations — reheating takes 2-3 minutes, cooking a meal 5-10 minutes. This limits the total energy consumed:
Reheating a meal (3 minutes at 1,200W input):
- Energy used: 1,200W × 3 min = 60Wh
- DC drain at 12V: ~5.5Ah from a 200Ah LiFePO4 battery = 2.7% of capacity
Cooking a jacket potato (8 minutes at 1,300W input):
- Energy used: 1,300W × 8 min = 173Wh
- DC drain: ~15Ah = 7.5% of capacity
On a 200Ah lithium battery, reheating food two or three times a day uses 5-8% of battery capacity — roughly 10-16Ah total. This is manageable on a well-sized system with adequate solar and alternator charging.
The key advantage of a microwave over an induction hob is the much shorter cooking time. A microwave uses more power per minute but for far fewer minutes. For reheating and simple cooking tasks, it is often more battery-efficient than simmering on an induction hob for 20 minutes.
System Requirements
For Occasional Reheating (1-2 times per day)
- Battery: 200Ah LiFePO4 minimum
- Inverter: 2000W pure sine wave
- DC cable: 50mm², under 1 metre, 250A ANL fuse
For Regular Cooking Use (3+ times per day)
- Battery: 300Ah+ LiFePO4
- Inverter: 2000-3000W pure sine wave
- Solar: 400W+ to replenish microwave usage
- DC-DC charger: 30A+ for alternator top-up
Best Compact Microwaves for Campervans
Russell Hobbs RHMM701 (17L, 700W) — ~£55
The most popular van life microwave. Compact at 45cm wide, 700W cooking output, draws approximately 1,100W. Fits under most van counters. Reliable and cheap to replace if it fails.
Daewoo KOR7LBKSL (20L, 700W) — ~£70
Slightly larger but well-regarded for reliability. Consistent 700W output, straightforward controls. The digital display uses minimal standby power.
Sharp R272SLM (20L, 800W) — ~£80
Solid mid-range option. 800W cooking output draws around 1,250W. Still manageable on a 2000W inverter. Good build quality for the price.
What to Avoid
- Combination microwaves with grill function — the grill element adds 800-1000W on top of microwave power, easily exceeding a 3000W inverter at full combination mode
- Any microwave over 1000W cooking output — DC current demands become extreme
- Very cheap unbranded microwaves — inconsistent power draw causes inverter instability
Practical Tips
Use the microwave on low power settings for longer. Reheating at 50% power for 6 minutes draws less peak current than 100% for 3 minutes, even though the total energy is similar. This reduces strain on the inverter and battery.
Turn the inverter on a few seconds before using the microwave. Inverters have a brief startup period. Starting the microwave immediately after switching on the inverter creates a combined inrush current that can trip the inverter's overload protection.
Check the inverter's peak power rating. Many inverters have a peak rating (e.g. "2000W continuous, 4000W peak"). Microwaves have a significant inrush current at startup — up to twice the running current. Your inverter needs to handle this peak. A 2000W continuous inverter with a 4000W peak will start a 1,200W microwave comfortably.
Monitor battery state. Never run the microwave when the battery is below 30% state of charge. The voltage sag under 100A+ draw can trigger the inverter's low-voltage cutoff, shutting down mid-cooking.
Microwave vs Induction Hob: Which is More Battery-Efficient?
For reheating and simple cooking, a microwave often wins:
| Task | Microwave | Induction Hob |
|---|---|---|
| Reheat meal | 60Wh (3 min) | 67Wh (5 min at 800W) |
| Boil 500ml water | 40Wh (2 min) | 60Wh (4.5 min at 800W) |
| Cook rice (2 portions) | 150Wh (8 min) | 300Wh (20 min at 900W) |
| Slow simmer (stew, 40 min) | Not suitable | 533Wh (40 min at 800W) |
For tasks the microwave can handle, it is generally more efficient. For tasks requiring sustained heat (browning, slow cooking, complex meals), an induction hob is the only option. Most van lifers with a serious electrical system fit both.
See our full induction hob in a campervan guide for the detailed induction picture.
FAQ
Can I run a microwave off a 1000W inverter?
No. Even the smallest 700W microwave draws 1,100W+ from the supply. A 1000W inverter will overload immediately. You need a minimum 1,500W inverter, with 2000W recommended.
What is the smallest microwave that works well in a campervan?
The 17-litre Russell Hobbs RHMM701 is widely used. At 45cm wide and 700W cooking output, it is compact enough for most van installations and has a manageable power draw.
Does a microwave work on solar power alone?
Technically yes — the microwave does not care where the power comes from, only that the inverter provides stable 230V pure sine wave. However, peak solar output in summer (UK: 300-1400W from a 400W system) is not enough to run a microwave at full power. The battery absorbs the difference. Using the microwave at midday in summer is more battery-friendly than morning or evening use.
Is it worth fitting a microwave in a campervan?
For the electrical cost (a good microwave is £50-80 and uses modest energy for short tasks), yes — if you already have a 2000W+ inverter. If you need to buy the inverter and upgrade your DC cables specifically for the microwave, the economics become less clear. In most builds the inverter is needed anyway (for laptop charging, power tools, etc.), making the microwave an almost-free addition.