A power inverter converts your vehicle's 12V DC battery power into 120V household AC, so you can run laptops, tools, and small appliances from your car or truck. Choosing the right one comes down to how many watts your devices draw — add up their wattage and pick an inverter rated comfortably above that total.
How to size a power inverter
- Add up continuous watts of everything you'll run at once (it's on the device label or charger).
- Add ~20% headroom so the inverter isn't maxed out.
- Check surge/peak watts — motors and compressors briefly pull 2–3× their running watts at startup; the inverter's peak rating must cover that spike.
Examples: a laptop + phone charger needs ~150–300W; a full-size cooler or power tools can need 750W+. The Battery Tender® 750W 12V Power Inverter covers most laptops, tools, and small appliances from a standard 12V system.
Pure sine vs. modified sine
Pure sine wave inverters produce cleaner power that's safer for sensitive electronics (laptops, medical devices, some tool chargers). Modified sine costs less and is fine for simple resistive loads. Check your device's requirements before buying.
Don't forget the battery
An inverter is only as good as the battery feeding it. Running high loads with the engine off can drain a starting battery quickly — for sustained use, run the engine or draw from a deep cycle/auxiliary battery. Keep the vehicle battery healthy with a smart charger from Battery Chargers.
The all-in-one option
If you want AC power plus a jump starter in one grab-and-go unit, the 2000 Amp Power Station with 100W Inverter delivers household outlets, USB, and cranking power without touching your vehicle battery.
Recommended Battery Tender® products
The 750W 12V Power Inverter for in-vehicle AC, or the 2000 Amp Power Station w/ 100W Inverter for a portable power + jump-start combo. Need a jump? See how to jump start a car with a battery pack.
Frequently asked questions
What size power inverter do I need for my car?
Total the running watts of your devices, add ~20%, and confirm the inverter's surge rating covers startup spikes. 300W handles electronics; 750W+ handles tools and small appliances.
Will a power inverter drain my car battery?
Yes if the engine is off and the load is high — run the engine for sustained use or draw from an auxiliary/deep cycle battery.
Do I need a pure sine wave inverter?
For sensitive electronics, yes; for simple resistive loads, modified sine is usually fine.
Can I plug an inverter into the cigarette lighter?
Only small inverters (~150W); anything larger must connect directly to the battery with proper gauge wiring.
What can a 750W inverter run?
Laptops, phone/tool chargers, TVs, and many small appliances — check each device's wattage against your total.
Related Battery Tender® guides: Automotive battery guides · How to jump start with a battery pack.
