What is Inside a D Battery?

flashlight with battery next to it

One of the most common types of alkaline batteries is a D battery. Common alkaline batteries range in size from the smallest AAA battery, to AA, to C, to the largest D battery. They are used to power larger electronic devices, such as portable stereos, large flashlights, and remote-controlled trucks.

This is because they give off more current than the smaller batteries. So you might wonder what is inside of a D battery that makes it work? We have the answer.

What is Inside

The D cell battery is a large storage casing for chemicals inside that create electrons. The battery contains two opposite terminals at each end of the casing, commonly referred to as the positive (+), and the negative (-), terminals respectively.

Inside the casing of the battery are carbon and zinc plates that are floating and rotating in an acidic substance such as sulphuric acid, manganese dioxide, or hydrochloric acid. The acidic paste acts as an electrolyte that creates a chemical reaction to produce electrons.

These electrons pile up at the negative battery terminal of the carbon because they have nowhere else to travel at that point and there are no reactions occurring.

How it Works

A buildup of electrons at the negative carbon terminal of the battery will lead to the battery supplying power to your device. The positive terminal of the battery contains zinc, which naturally draws electrons.

If you connected a wire from the positive terminal to the negative terminal, the energy of the battery would quickly vanish as the electrons race to the zinc plate at the positive terminal through the wire. When the battery inserts into an electronic device, each terminal connects to a wire.

The negative terminal then creates a path for the electrons to travel through the wiring of the electronic device. This powers the equipment along the way until the electrons reach the positive terminal at the end of its journey. This flow of electrons is what makes your toy truck’s wheels spin or your radio play music.

This, in essence, turns the device into a circuit for the path of electrons.

D Battery at its End

Batteries are not infinite, and this is due to the loss of zinc found at the positive terminal of the battery. D batteries will usually last about 60 times longer than an average AA battery. The length of the battery’s life comes from the capacity the battery has and the drain that is applied to it from the device it is powering.

An average D battery has a capacity (mAh) of 12000 and the typical drain (mA) of 200. Over time, each cycle of electrons passing through the battery will chip away at the zinc plate. Once the zinc plate is totally gone the battery is dead and must be replaced.

Rechargeable batteries are also an option and can save money over time, as opposed to buying new batteries each time you need to replace them.