Truck Encyclopedia (13): How to calculate the power of the cigarette lighter?

The cigarette lighter is arguably one of the oldest accessories in the car configuration, dating back to the fifties of the last century. As an ancient configuration, cigarette lighters have existed to this day, why hasn't cigarette lighters been canceled? The very important reason is that all kinds of on-board electrical appliances are powered by cigarette lighter sockets.

▎The history of the small cigarette lighter is not short

The predecessor of the cigarette lighter was called "electronic cigar lighter" and was invented by a German inventor in the 80s of the 19th century. The cigarette lighter heating element of this period was connected by a wire, and it was as convenient as a match.

In 1921, Morris, an American, patented the world's first "cordless" lighter he designed. This cigarette lighter is heated in an outlet, then heated and then removed for use manually. This was the prototype of the cigarette lighter today.

In 1956, the American company Casco developed a modern cigarette lighter, which was patented in 1960. Later cigarette lighter designs eventually adopted coiled heating elements, pop-up action, and standardized size, becoming a common configuration in automobiles. Today's cigarette lighters are powered by 12V DC for small cars and 24V for trucks.

The earliest use of cigarette lighters was to light cigarettes for drivers or passengers, but now it is more used to provide charging.

The structure of the cigarette lighter socket is simple, the elastic head in the middle of the bottom of the socket is the positive electrode, and the two sides are the negative electrode. When using, you only need to plug the cigarette lighter into the cigarette lighter socket, which is very convenient to use.

The internal structure of cigarette lighter plugs is also different depending on the purpose. Premium cigarette lighter plugs also have separate fuses inside for added security.

▎Cigarette lighter pays attention to the correct use

It is said that since the last time Lao Wang bought a new car, it has been a few months, and during this time, Lao Wang has not forgotten to add various equipment to the car. What a navigator, a dash cam, a kettle, a rice cooker, etc. are all available. On this day, Lao Wang stopped to cook in the service area, and he didn't know what was going on, but the cigarette lighter suddenly ran out of power, causing Lao Wang to eat a half-cooked meal of rice.
 

Why does the cigarette lighter suddenly run out of power? Is the battery dead? But the vehicle started normally, and all kinds of lights and instruments were normal, but the cigarette lighter was out of power. Lao Wang was busy calling expert Lao Li again. When Lao Li heard the reason, he asked Lao Wang to open the safety box to check the fuse of the cigarette lighter, but sure enough, the fuse of the cigarette lighter burned out.

It is normal to use low-power electrical equipment in the car, but when high-power heating appliances such as rice cookers and electric kettles are used in vehicles, it is inevitable that people will be a little worried, and the safety hazards are great?

If the bearing capacity of the circuit is exceeded, the circuit will trip, the fuse will be burned, and there is a risk of fire at worst.

So, how much power can our truck cigarette lighter hold?

Let's first review the physics knowledge in junior high school.

The formula for calculating electrical power: electrical power = voltage × current, that is, P = UI

According to the above formula, if we know the maximum current (I) of the cigarette lighter line, we can calculate the maximum power (P) that the line can withstand.

So, how do cardholders get the maximum amperage of the cigarette lighter line?

In fact, it is very simple, we only need to look at how safe the fuse of the cigarette lighter is.

The fuse carrying value of each model and brand is different, but it is basically around 10A-20A. Lao Wang's cigarette lighter fuse is 10A.

If calculated by 10A, then the maximum carrying capacity of Lao Wang's cigarette lighter is 24V×10A=240W.

However, 240W is a limit value, and when this value is exceeded, the fuse is likely to burn out. Therefore, when Lao Wang uses electricity in the future, the rated power of electrical appliances must be lower than the value of 240W.

According to our observations, most of the cigarette lighters on trucks now have a power between 120W and 180W, and a few have an output power of 240W. Therefore, cardholders should pay attention to the rated power value of electrical appliances when purchasing on-board electrical appliances.

And now the power value is clearly marked on the cigarette lighter lid of most trucks, which is more convenient for everyone to identify.

Well, we have figured out the carrying capacity of the cigarette lighter line. So among the on-board equipment commonly used by card friends, which devices can be used with confidence, and which ones should be used carefully?

● Car charger

点烟器插座现在The most commonly used function should be charging the phone. The car charger is usually a 12V to 5V power adapter, and its charging current is generally 1A or 2A, that is, the power during charging usually does not exceed 10W (5V×2A), so the car charger does not have any pressure on the cigarette lighter line.

Safety index: ★★★★★

● Dash cam

Nowadays, many card friends have installed dash cams, but some are powered by modified lines and obtained power from the body wiring harness, and some are powered by cigarette lighter sockets. The general driving recorder has a working current of about 1-2A, which is not at all under the cigarette lighter line

Safety index: ★★★★★

● Car refrigerator
 

The power of the car refrigerator basically does not exceed 120W, taking this car refrigerator in the truck home mall as an example, its maximum power is only 45W, which is very safe for the cigarette lighter line.

Safety index: ★★★★★

● Car electric kettle, car rice cooker

Just by seeing the name, everyone knows that these two must be high-power electrical appliances. The power of this type of car heating appliance is generally 100-200W or even higher. Taking the car electric kettle in the picture above as an example, the maximum power of this electric kettle has reached 240W, which is the same as the maximum carrying capacity of the cigarette lighter of 240W.

Therefore, when purchasing such products, the bearing capacity of the cigarette lighter circuit needs to be fully considered.

Safety index: ★★★

● On-board inverter

The on-board inverter output through the cigarette lighter is 20W, 40W, 80W, 120W to 150W power specifications. No matter how high-power the inverter power supply is, it is generally directly connected to the battery through the connecting wire, and the power of this inverter can even be several thousand watts.

When purchasing an inverter, especially a high-power inverter, its safety performance must be fully considered, and it must have good short-circuit and overload protection functions.

Safety Index: ★★

Finally, there is one more thing to emphasize to you. Some card friends see that their original cigarette lighter fuse is relatively small, so they want to change to a larger fuse, and Truck Home once again emphasizes that this approach is not advisable!

Fuse is related to vehicle safety, and manufacturers choose models based on the bearing capacity of their related lines. There is a saying in circuit maintenance, "insurance is better to replace big with small than small to big", because big for small brings "excessive safety", and small for big brings safety hazards!