A flat battery is an originally developed by Paul Schmidt battery in which three cells are connected in series in series. Most are zinc - carbon cells, each with 1.5V voltage; in this case is the IEC designation of this battery 3R12. Come alkaline manganese cells used, is the name 3LR12. The positive pole is accordingly on the short connector tongue, the negative lead to the long tongue.

The series connection of a total voltage of 4.5 V. flat batteries results can not be recharged.


The flat battery loses partly due to its bulkiness increasingly important; most of their areas of application can also be served thanks to energy-saving technologies, which require a lower voltage by batteries ( AA).

In many cases, flat batteries are no longer commercially available. Using the adapter ( three AA batteries ) but can also continue to operate equipment. This is also the only way to use rechargeable NiCd or NiMH batteries in appropriate devices as batteries or chargers exist suitable for the flat battery.

Areas of application

Commercial use

Flat batteries are still used ( box-shaped flashlights ) nor by different manufacturers (among Crone, Duracell, Panasonic, Varta ) in box lights. The advantage is the portability (only one instead of three batteries must be installed), and the increased current capacity due to the better utilization of space (approx. 5900 mAh instead of 2200-3500 mAh in Mignon, see battery sizes). Until the early 1970s, she was found also in transistor radios. Analog gauges for measuring the resistance with respect to their energy requirements in part also from flat batteries.


Traditionally, the flat battery is used because of the well contactable long terminal lugs for smaller craft projects in shop class or in groups of children. In the context of the theory of electricity it takes to build simple circuits using. In some cases, the voltage of 4.5 V saves a costly series other ( radially symmetrical ) batteries. The terminal lugs often serve as a switch, so that with a light bulb and some tape quickly a simple flashlight is made due to its spring action. A row ( higher voltage ) or parallel ( higher amperage ) of several flat batteries comes with the appropriate connecting the terminal lugs into existence (in the simplest case with paper clips). Due to the decreasing market presence of flat batteries 9 volt block sets for craft tasks more and more.

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