An undersized inverter is one of the most common van electrical mistakes — not because it fails outright, but because it works fine until the one appliance with a real startup surge trips it, usually mid-trip, usually at the worst time.
The Two Numbers Every Inverter Has
Every inverter is rated for continuous watts (what it can sustain) and surge/peak watts (a short burst it can handle, typically 2-3x the continuous rating). Size for both, or you'll trip the inverter the moment a compressor-based appliance kicks on.
Step 1: Add Up Continuous Wattage
List everything you might realistically run at the same time through the inverter — not everything you own, just realistic simultaneous use:
| Appliance | Continuous Watts |
|---|---|
| Compressor fridge (running) | 60–150W |
| Laptop charger | 65–100W |
| Induction cooktop (single burner) | 1,200–1,800W |
| Coffee maker | 800–1,200W |
| Blender | 300–1,000W |
| Microwave (small) | 700–1,000W |
If your worst-case combination is "fridge running + laptop charging + induction cooktop on," that's roughly 1,400-2,000W continuous — your inverter needs to be rated above that.
Step 2: Check Surge/Startup Wattage
Compressor-based appliances (fridges, some pumps, microwaves) draw a short surge — often 2-3x their running wattage — for a fraction of a second on startup. A fridge that runs at 60W might surge to 180-200W on startup. This usually isn't the deciding factor unless you're running several compressor devices simultaneously, but it's worth checking your inverter's surge rating against your highest single-appliance surge.
Common Inverter Sizes and What They Actually Handle
| Inverter Size | Realistically Handles |
|---|---|
| 300–600W | Laptop, phone charging, small fans, LED lighting — no cooking appliances |
| 1000–1500W | Adds: blender, small microwave, coffee maker (one at a time) |
| 2000–2500W | Adds: induction cooktop, most microwaves, running multiple appliances together |
| 3000W+ | Heavier setups: full kitchen use, power tools, larger A/C units |
Match Inverter Size to Wire Gauge and Battery Capacity
A bigger inverter isn't free — it draws more amps from your battery bank at the same voltage, which means thicker wire and a battery bank sized to actually sustain that draw without dropping voltage. A 3000W inverter on 12V draws roughly 250A continuous at full load — wire and fusing for that circuit needs to be sized accordingly (see our wire gauge guide), and a small battery bank will sag under that load even if it has enough total capacity.
Pure Sine vs Modified Sine
Most modern van builds use pure sine wave inverters — they produce cleaner power that's safe for sensitive electronics (laptops, some fridge compressors, medical equipment) and don't cause the humming or interference that modified sine wave inverters can. Modified sine is cheaper but increasingly uncommon in new builds because so many devices now expect clean sine wave power.
Frequently Asked Questions
Is a 2000W inverter enough for van life? For most moderate builds running one high-draw appliance (induction cooktop or microwave) at a time alongside a fridge and electronics, yes. Heavier simultaneous use (A/C, power tools) may need more.
Do I need pure sine wave for a van conversion? Recommended for most modern builds — it's safer for sensitive electronics and avoids compatibility issues with compressor-based appliances that modified sine wave inverters sometimes struggle to run properly.
Why did my appliance trip my inverter even though it's rated high enough? Usually a surge/startup spike exceeding the inverter's peak rating, not its continuous rating — check the appliance's startup surge, not just its running wattage.