The Wittfeld-type battery railcars were procured by the Prussian State Railways from 1907 in order to obtain a cheap and easy-to-operate means of transport for passenger transport on branch lines. The designation came from engineer Gustav Wittfeld, who designed the concept for these vehicles at the Ministry of Public Works. The requirement was that around 100 people should be transported at 50 km/h and that the capacity of the batteries should be sufficient for a range of 100 km. Since the acid in the batteries at that time gave off larger amounts of foul-smelling gases, the desire for a separation of the passenger compartment from the batteries was also expressed, as was not the case with the first battery-powered railcars.

The first of the railcars built consisted of two halves, each with two axles, of which the inner one was powered. At each end there was a hood for accommodating the batteries. Since these were very heavy and brought the axle load to a level that was critical for branch lines, the individual axles at the ends were replaced by two steering axles from 1913. All existing copies were also retrofitted in this way. To increase the passenger capacity, a passenger car was sometimes attached to the railcars. Since this was only a temporary solution, eight examples were later built with a trailer. This also received the traction motors, while the batteries remained in the end cars.

Inside, the vehicles differed depending on the requirements, but mostly they only had third and fourth class seats. In the latter there were also some standing places, more were made available in the rear driver's cab. In some railcars there was a second class compartment and/or a luggage compartment and in some cases toilets.

The vehicles were designated AT₃ from 1909 and were initially used primarily in Poland. Even after the First World War, some came to Poland as reparations. In service with the Reichsbahn, the area of application expanded to other regions in Germany. After the Second World War, the remaining railcars on the territory of the Federal Railways were reconditioned, since a large number of them were no longer in a roadworthy condition. Depending on the type of electrical equipment, they were designated ETA 177, 178 and 180 and remained in use until 1964. In the GDR, her life ended in 1954 because there were no funds for reconstruction.

These vehicles, also known by their later DB designation ETA 179, were put into service by the Reichsbahn from 1926 dubbed the “six-axle storage railcar”. A total of only 17 units were built, but these were used very extensively, especially on branch lines. Some locomotives achieved mileages of almost 10,000 km per month in the thirties.

The railcars consisted of two parts, each of which had three axles approximately equally spaced. The inner axle was driven, the energy for it came from accumulators mounted under the floor. With the state of the art at the time, these accounted for a considerable part of the total weight and, with their total capacity of 225 kWh, allowed operation for around three hours. With an output of 142 to 172 kW and a service weight of at least 70 tons, the cars reached 60 km/h, which was sufficient for branch lines and spared the batteries.

All but one survived the war and were then used by both German railway administrations. The Bundesbahn received eleven units and used them as ETA 179 until 1960. The Reichsbahn received the remaining five and continued to operate them with the original numbering. They were last used in the Gotha area and were retired in 1968. One of these is the only survivor today, having returned to its last operational area in 2001 in a very badly weathered condition. Since then it has been painstakingly restored to its original state.

Shortly after it was founded, the Bundesbahn decided to purchase new railcars for branch lines with low operating costs. Looking back on the battery railcars successfully used by the Prussian State Railways and the Reichsbahn, it was decided to develop new battery railcars. Since ultimately it was also to be used on main routes, a maximum speed of up to 100 km/h was required without having to sacrifice the high acceleration when operating on secondary routes with many stops.

Finally, in 1952, the first two prototypes were delivered, the mechanical part of which came from Wegmann and the electrics from Siemens and AEG. This was followed in 1954 by three more with mechanical parts from Wegmann and WMD Donauwörth, all of which were supplied with the electrical part from Siemens. Since the vehicles only had a driver's cab at one end, eight corresponding driving trailers were built short time after.

The car bodies were designed with a stable floor pan that could carry the heavy batteries with a capacity of 940 ampere hours. Above that was the passenger compartment, which initially included first, second, and third class. From 1956 only the first and second class was run. Power was transmitted to one of the two bogies, which was equipped with two light, high-speed traction motors. These allowed a top speed of 90 km/h for the first two vehicles and 100 km/h for the remaining ones. Sufficient acceleration was ensured by permitting to overload the traction motors briefly to start off.

The vehicles were distributed over several depots, but were very rarely relocated during their lifetime due to the necessary charging facilities. Depending on the route profile, up to 250 miles could be covered with one battery charge and one charging process per day could be expected. From 1968 the powercars were listed as class 517 and the driving trailers as class 817. Electronic control and regenerative braking were later tested on the vehicles. Experience with these vehicles led to the development of the ETA 150, which went into series production from 1954. The eight ETA 176 were only retired between 1981 and 1984.

Since the eight prototypes of the ETA 176 series proved themselves, their development as the ETA 150 was built in series from 1954. Externally, the production vehicles not only differed from the ETA 176 in terms of the revised front end, but also in terms of their conventional buffers and screw couplings. This meant that conventional passenger or freight cars could also be carried, while the predecessors could only be coupled to the specially made control cars.

Since the ETA 150 only had a driver's cab on one side, 216 control cars were built to go with the 232 motor cars. With 23.40 m, they were shorter than their predecessors and were delivered with different layouts of the passenger compartment, which had a different number of seats in first and second class. The traction motors now each had 150 instead of 100 kW. In the course of production, larger and larger batteries were installed, which were exchanged for the largest available model every four years. Depending on the route, the range was between 250 and 400 km. Since the high weight of the battery hung between the bogies, the car bodies sagged over time, which led to the nickname “Hängebauchschwein” (pot-bellied pig).

Over time, the vehicles deployed in significant numbers received several nicknames, such as “Whistle Buoy” or “Maya the Bee” referring to the running noise. Otherwise, they were also called “Battery Flash”, “Acid Bucket”, “Socket Intercity” and “Flashlight Express”. They were used almost exclusively on flat land to prevent the batteries from draining too quickly. From 1968 the motor cars were redesignated as the class 515 and the control cars as the class 815. From the 1980s onwards, they were mainly replaced by class 628 diesel railcars and were completely phased out by 1995.