Choosing the right inverter size is essential to safely and efficiently power your appliances while camping, touring, or living off-grid. In this guide, we’ll break down the inverter sizes needed to run common household appliances like fridges, kettles, and microwaves from a 12V battery system.
⚡ What Is an Inverter?
A power inverter converts DC power from your battery (usually 12V or 24V) into 240V AC so you can run standard household appliances while off-grid or in a vehicle. Pure sine wave inverters are recommended for appliances with motors, heating elements, or sensitive electronics.
? How to Choose the Right Size Inverter
To select the correct inverter, you need to:
Know the appliance’s wattage (usually found on the label or in the manual).
Add 20–30% extra headroom to account for startup surges.
Consider continuous (rated) and peak (surge) power of the inverter.
? Common Appliances and Inverter Size Recommendations
| Appliance | Average Power Draw | Recommended Inverter Size | Notes |
|---|---|---|---|
| 12V Camping Fridge (Compressor Type) | 40–100W | 300–600W Pure Sine Wave | Low draw; even small inverters work well |
| Household Bar Fridge | 150–300W | 600–1000W Pure Sine Wave | Allow for compressor surge (up to 2–3x running watts) |
| Kettle | 1500–2400W | 2500–3000W Pure Sine Wave | One of the highest draw appliances |
| Microwave (700–1000W) | 1000–1500W | 2000–3000W Pure Sine Wave | Inverters must support peak draw |
| Laptop Charger | 50–90W | 300W Inverter or smaller | Modified sine wave is often OK |
| TV (LED 32–55") | 60–120W | 300–600W Inverter | Pure sine wave preferred for stable output |
? Important Notes
Startup Surge: Appliances like fridges and microwaves draw 2–3x more power at startup. Make sure your inverter has a surge capacity.
Battery Size Matters: A 3000W inverter won’t be useful if your battery can’t supply enough current. Use lithium batteries (LiFePO4) with high discharge capability.
Cable Gauge: Larger inverters need thick cables (often 0AWG or 50mm²) to avoid voltage drop and overheating.
? Battery Drain Example
Running a 2400W kettle for 5 minutes from a 12V battery:
2400W ÷ 12V = 200A draw
200A × (5/60) = ~16.6Ah used in 5 mins
This is a massive draw and not recommended for small battery banks. A gas kettle or stovetop is more efficient when camping.
✅ Quick Tips
Always use pure sine wave inverters for fridges, kettles, and microwaves.
Choose an inverter with at least 20% higher rating than the appliance’s continuous draw.
Pair high-wattage inverters with lithium batteries and proper fusing.
Avoid overloading your inverter — check both the continuous and surge ratings.
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