You’ll see two main 12V heater styles on this page:

• 12V plug‑in car heaters/defrosters: Compact units that plug into your vehicle’s 12V accessory socket. They’re designed to help defog or spot‑defrost the windshield and can rotate to direct airflow. Many offer simple heat/cool fan modes.
• 12V diesel air heaters: Higher‑output systems that create heat from diesel fuel while using 12V power for the fan and controls. Options include all‑in‑one kits with a built‑in tank and muffler, plus features like LCD screens, remotes, Bluetooth app control, and altitude modes.

Match the heater to your use case (daily commute, RV, truck, boat, or workshop), check wattage/amp draw, and review installation and ventilation requirements before buying.

It depends on the heater’s wattage and your battery’s usable capacity.

• Quick math: Approximate runtime (hours) ≈ usable battery watt‑hours ÷ heater watts.
• Example: A 12V 50Ah battery stores ~600Wh. Using ~50% to protect a starter battery gives ~300Wh. A 150W 12V defroster could run for about 2 hours.
• Diesel air heaters: They use 12V mainly for the fan/control. Most heat comes from fuel, so the electrical draw after startup is usually lower than plug‑in heaters. Check the spec sheet for current draw.

Temperature, battery health, and wiring losses affect results. To reduce the risk of a no‑start, consider a dedicated deep‑cycle battery and correct fusing. Always verify your heater’s specifications.

You can shop 12V heaters right on Walmart’s Auto & Tires pages.

• Use filters to narrow by type (diesel air heater or 12V defroster), wattage, tank size, and features like LCD, remote, or app control.
• Open product pages to review compatibility notes, installation details, and customer reviews for real‑world insights.
• At checkout, choose delivery or pickup options that fit your schedule.

If you’ll need accessories later, look for listings that include parts such as ducts, mufflers, and switches. The product Q&A section can also help with fit and setup questions before you buy.

Heating takes a lot of energy, so portable battery‑powered heaters have limits.

• Most 12V options here either plug into a vehicle’s 12V socket (compact defrosters) or use diesel fuel for heat while drawing 12V for controls.
• Truly battery‑only space heaters are uncommon and typically run for a short time before needing a recharge.
• A portable power station may run a low‑watt 12V defroster briefly, but capacity, inverter limits, and temperature influence runtime.

For travel or off‑grid use, purpose‑built 12V solutions can be more practical. Always follow the manufacturer’s guidance on wiring, ventilation, and clearances for safer operation.

Good installation and ventilation are key for 12V diesel air heaters.

• Mount correctly: Install on a stable surface per the manual and maintain required clearances.
• Vent properly: Route the exhaust outdoors and away from people or materials; never block it.
• Wire safely: Use the recommended fuse and cable gauge to your 12V supply, and protect wiring from abrasion.
• Fuel handling: Secure the tank upright and check all lines and fittings for leaks.
• Test and monitor: Do a trial run in a well‑ventilated area, adjust settings (e.g., altitude mode if available), and avoid leaving units unattended.

Conditions vary, so always follow the product’s instructions and local guidelines.