12 Volt Heaters for Cars and Trucks: What Actually Works
A vehicle power socket delivers about 150 to 180 watts. A car’s own heater puts out several thousand. So a plug-in “12-volt space heater” will never warm a cab — but the same power, put where you are, works well: heated blankets and pads warm you directly, and a 12-volt bed warmer keeps a sleeper berth comfortable all night on a few amps. Here is what each option does, what it draws, and when you need something bigger.
- Heat the person, not the cab: a heated blanket or pad on a 12-volt socket is the most effective use of the power available
- Wired-in 300-watt heaters, such as the Rampage, add heat to cold spots in a vehicle that already has a working heater — they do not replace it
- With the engine off, everything here runs from the battery; a starting battery is not built for long, deep draining
- On a 24-volt truck, choose a 12/24-volt product such as the Comfytemp pad, or use the truck’s 12-volt socket
Pick by how you want to stay warm
| Size | Power | Controls | Connects | ||
|---|---|---|---|---|---|
|
Stalwart 12V Heated Car Blanket
Blanket
|
59 × 43 in | Not stated | On/off | 12 V socket | BUY NOW |
|
12V Heated Car Blanket with Timer
Blanket with timer
|
57 × 40 in | Not stated | Low/high, timer | 12 V socket | BUY NOW |
| 58 × 42.5 in | Not stated | On/off, about 100–130°F | 12 V socket | BUY NOW | |
|
Comfytemp 12V/24V Heated Pad
Heated pad
|
12 × 24 in | 96 W | 4 settings, timer | 12/24 V socket | BUY NOW |
|
ElectroWarmth T36 Bed Warmer
Bed warmer
|
36 × 60 in | 6.2 A max | 7-setting thermostat | 12 V socket | BUY NOW |
|
Rampage 300 W Back Seat Heater
Wired-in heater
|
— | 300 W (about 25 A) | Heat/fan switch | Wired in | BUY NOW |
Will a 12-volt heater warm my car or truck cab?
Not on its own. A lighter socket supplies about 150 to 180 watts, while a vehicle’s built-in heater delivers several thousand watts of heat from the engine. Plug-in “12-volt space heaters” and fan heaters warm the air right in front of them and little else. That is why heated blankets and pads work so much better: they put the same power into you instead of the air.
Will a heated blanket drain my battery?
It can, slowly. Typical 12-volt blankets draw around 4 to 5 amps, so an hour with the engine off takes about 4 to 5 amp-hours from the battery — fine for a short stop, but a starting battery is not built for a whole night. Run the engine for longer use, or in an RV or truck with a house battery, run from that. Unplug when you leave: some sockets stay live with the ignition off.
What can I use for heat while sleeping in my truck?
A 12-volt bed warmer such as the ElectroWarmth T36 heats the berth itself and draws at most 6.2 amps, averaging about half that as its thermostat cycles, so a night on a house battery is realistic. For warming the whole cab with the engine off, truckers generally use a diesel-fired air heater, which burns a little fuel and needs only a small amount of 12-volt power for its fan — something we do not carry.
My truck is 24 volts — what works?
The Comfytemp heated pad plugs into either a 12-volt or a 24-volt socket. The blankets, the bed warmer and the Rampage heater are 12-volt only: use the truck’s 12-volt socket if it has one, or a 24-to-12-volt voltage converter sized for the current.
Can I run a household space heater from an inverter?
Technically yes, practically no. A 1,500-watt space heater draws about 150 amps from a 12-volt battery through an inverter — it would flatten a typical battery in well under an hour and needs a 1,500-watt-class inverter wired directly to the battery with heavy cable. The inverter calculator shows the numbers for your setup. For heat, a 12-volt blanket or bed warmer goes much further.
What happened to the ThermTech Back Seat Heat Plus?
ThermTech no longer makes the 3000C and 4000 Back Seat Heat Plus. The closest current equivalent is the Rampage 300-watt back seat heater: like the ThermTech, it wires into the vehicle rather than plugging into the lighter socket, and puts out 300 watts of supplemental heat.
Bottom line
Put the heat where you are. For drivers and passengers, a 12-volt heated blanket — the Stalwart, the timer blanket or the BCG811 — or the Comfytemp pad, which also runs on 24-volt trucks, does far more than any plug-in space heater. For sleeping in a truck or RV, the ElectroWarmth T36 bed warmer runs all night on a few amps. To add heat to a cold back seat in a vehicle that already has heat, the wired-in Rampage 300-watt heater is the option. Keep an eye on the battery with the engine off.
