Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

Received similar question and failure report regarding the cigarette lighter socket on many occasions so hope following information helps.
Some of the photos are from years ago so may no longer applicable these days.

First, the socket design itself is defined around the world in JIS, SAE, DIN, etc.
Unfortunately, not all of them are the same.

Also, within the same standard, there could be 2 different spec.
The differences are mainly the diameter and deviation depending on the voltage in use, etc.

Normally, the socket and the lighter are provided as a pair so you may not notice the above.
The problem occurs when one tries using the aftermarket accessory plug.






Within JIS, while the socket design was defined, the plug design for the purpose of taking the electrical power was only shown as reference and not as the definite specification.

Thus, you will find all sorts of different plug designs from many manufactures.

For example, the three plugs on the right have some level of consideration for the cigarette lighter socket.

There is a recess at the end of the plug to allow the bimetal spring to escape.
More on this later when going through the socket design.

On the other hand, the two at the left has just a curved edge so it will simply push away the bimetal terminals.
Will touch on this later.


Nowadays, the modern cars come with auxiliary power socket designed mainly for providing the power for the accessory products such as the USB power adaptor, charger, air pump, etc.

It is not to be used for the cigarette lighter and most likely, it won’t work due to the specific lighter design.

Because of the difference in socket design standard around the world and multiple plug design, it can cause problem due to intermittent contact, short circuit or even mechanical damage.

Depending on the plug diameter and the design of the positive centre terminal, it may not make good contact against the socket positive terminal.

Compared to other aftermarket plug design, the OEM tyre airpump has really good centre terminal size and shape.