Top 12V Electric Portable Car Heaters

Electric portable car heaters are something of a mixed bag, in that they don’t always work exactly like you’d expect a replacement car heater to work, and your satisfaction will ultimately depend on your expectations. Some car heaters, like oil pan and block heaters, absolutely perform the function that they’re designed to do, while replacement heaters are often anemic in comparison to the systems that they are replacing.

This is especially true of 12V car heaters, even more so of electric heaters that are designed to be plugged into a cigarette lighter socket, while 120V electric car heaters are often much more capable of warming up the interior of a car or truck.

In the interests of helping you keep toasty warm as the long, cold winter months set in, let’s take a look at four examples of portable car heaters that are representative of the main options you have at your disposal.

A Word of Caution About 12V Car Heaters

cold CAR
No heat means no defroster, right? Well, maybe not!. Michael Courtney / E+ / Getty

When most people think about getting a portable electric car heater to replace a broken car heating system that’s just too expensive to fix the right way, this is what they usually think of. These heaters are designed to run off a car’s electrical system, so they can be used when you’re driving. They’re typically also designed for use in close quarters, unlike residential space heaters that tend to catch things on fire when you don’t leave a large enough air gap.

Unfortunately, 12V car heaters suffer from a few problems across the board, with the main issue being a lack of heat output. This is a simple problem of how much power is available to this type of heater, especially when it’s plugged into a cigarette lighter socket instead of wired directly to the battery or plugged into an inverter.

RoadPro RPAT-858

RoadPro RPAT-858 electric heater
Small electric car heaters are usually good for demisting/defogging, if that. Image courtesy RoadPro

Connection: Cigarette lighter
Wattage: 180W
Usage: Demisting

RoadPro’s RPAT-858 is a prime example of the type of electric car heater that can be plugged directly into a cigarette lighter socket. Like most heaters in this class, the RPAT-858 is relatively small and is designed to be installed on your dash. Also like most heaters in this class, the amount of heat you can expect out of this unit isn’t really anything to write home about.

The RPAT-858 is a 180 watt heater, which is why it can be plugged into a 15A cigarette lighter circuit, but that’s also why it doesn’t generate a tremendous amount of heat. By way of comparison, a decent residential space heater will often be rated at  750/1,500W.

Electric car heaters like this do put out a small amount of heat, but you shouldn’t buy one expecting it to replace—or even stand in for—a broken car heater. These heaters are better used as defrosters, but even then they work better as defogger/demisters than actual defrosters. If your windshield is actually covered in ice, you’ll have better luck with other solutions.

Schumacher 1224

schumacher 1224
Some electric car heaters have more than one wattage option. Image courtesy Schumacher Electric

Connection: Cigarette lighter / accessory socket
Wattage: 150/235W
Usage: Demisting/light heating

The Schumacher 1224 is an example of a portable electric car heater that can be plugged into a cigarette lighter socket, or used with a dedicated accessory socket to provide more heat. Unlike smaller units, and more like residential heaters, electric car heaters like the Schumacher 1224 can operate in two modes.

In the case of the 1224, it can operate as a 150W or 235W heater. The 150W setting is designed for use with the stock cigarette lighter socket in your car, just like smaller heaters like the RPAT-858. In order to use the 235W setting, you need to use a dedicated accessory socket. So if your car didn’t come with an accessory socket that’s rated at more than 15A, you’ll have to install one to take full advantage of a heater like the Schumacher 1224.

Of course, you’ll still have to temper your expectations with a heater like this. Even if you use an accessory socket and run a unit like this in the higher amperage mode, the amount of heat you get out of it won’t be anything like what you’re used to getting out of your car’s heater. While 235W is significantly more than 180W, it’s still a far cry from a residential heater.

RoadPro RPSL-681

roadpro RPSL-681 heater
Higher wattage electric car heaters can't be safely plugged into a cigarette lighter socket. Image courtesy RoadPro

Connection: Directly wired to the car battery
Wattage: 300W
Usage: Light/supplemental heating

At the opposite end of the spectrum from cigarette lighter heaters, you have portable car heaters like the RoadPro RPSL-681. These heaters can’t be plugged into a cigarette lighter socket, and some don’t even come with 12V plugs at all. In most cases, you have to actually wire this type of heater directly to the battery, preferably with an inline fuse to prevent an electrical fire in case of a short circuit. Although the RPSL-681 comes with two built-in 20A fuses, it’s still recommended to install it with an in-line 30A fuse.

The reason that you can use a heater like the RPSL-681 with a cigarette lighter socket, or even a factory accessory socket, is that it’s rated at 25A and 300 Watts. That’s almost twice the wattage of the RPAT-858, and edges out dual use heaters like the Schumacher 1224 enough that you really need to run 12 gauge or thicker power cables to the battery to run it.

DC Thermal SA12-5000

DC Thermal SA12-5000
More heat means more watts means more amps, and not all alternators can handle that. Image courtesy DC Thermal

Connection: Directly wired to the battery
Wattage: 600W
Usage: Temporary replacement heat

While the RPSL-681 is fairly representative of electric car heaters that have to wired directly to a car’s battery, it’s always possible to go bigger.

For example, the DC Thermal SA 12-5000 is a 12V electric heater that’s rated at 600W. This type of car heater absolutely has to be wired to the battery with an appropriate fuse, and it may also require an aftermarket high output alternator. And even then, these units are much better at heating small truck cabs and even smaller spaces like skidsteer cabs than cars or large SUVs.

Tempering Expectations With 12V Electric Car Heaters

Before you run out and buy a portable heater like the RPSL-681, or even a DC Thermal SA12-5000,  to replace your broken car heater, it’s important to remember that 300 or 600 Watts still isn’t all that much in comparison to other heaters you might be used to. It’s definitely better than nothing, and it might be enough to get you by until you can afford to fix your broken car heater the right way, but you shouldn’t buy one of these expecting it to be a direct replacement.

An easy way to explain why this type of heater isn’t ever going to match a residential space heater, if you aren’t familiar with wattage, is to think of a hair dryer.  A very common wattage for a hair dryer is 1,875W, and even small, portable hair dryers are often rated at 1,200W or more.

Now think about trying to warm up your car by blowing a hair dryer in through the window, except the window is open and less than 20 percent of the hot air is actually getting in the car. It would probably take a pretty long time to actually warm the car up, right?

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