Internal Battery Design History

The wireless revolution lead to an increase in use of PDAs, MP3s, MP4s, Laptops, Smart phones, DVD players and other portable devices. This increased the need for smart and high capacity portable batteries. Old portable batteries however, were not typical in design.

First, high performance portable devices require an electrical current. There are two kinds of electricity (direct current and alternating current flow). Direct current means that the flow of charge in one direction. A battery delivers direct current (DC) because there is no way to change the + and – see you on the battery.

To create direct electrical current electrons must break atoms which leads to an Electrons flow. Why? The answer is because electricity is a property of certain subatomic particles (protons, electrons and neutrons) which couples to electromagnetic fields and causes attractive and repulsive forces between them, by an electric current that is generated, and that is where power comes from. Let’s explain!

Scientists have opportunities to large numbers of positive atoms and free electrons found to create negative (in other words, they have to part ways and means found by electron / atoms). Since overpopulated proton (positive) atoms want electrons (negative), so that they can be balanced, these positive atoms have a strong attraction for electrons. The manufactured disequilibrium creates a state of continuous flow of electrons to atoms with an overpopulation of protons (positive atoms). When electrons move from one atom to another atom a current of electron flow (which is how we get electricity) is created.

This current can then be collected, stored and used to power a device. In a portable battery, generation of electricity begins with a chemical reaction. To cause electrons to be made from atoms a chemical reaction needed.

Lithium is used, among many other applications, such as a battery anode material (due to its high electrochemical potential) and lithium compounds are used in dry cells and batteries. In fact, the energy of some lithium cells were five times larger than an equivalent-sized lead-acid cell and three times greater than alkaline batteries. Lithium cells often have a starting voltage of 3.0 V. This means, that batteries can be lighter, have lower per-use costs and have higher and more stable voltage profiles.

In PDA batteries lithium is converted from chemical energy into electrical energy. This process makes a battery an electrochemical device that stores chemical energy and releases it as electrical energy according to demand.

Chemical reactions are strongly influenced by their environment. The environment of an internal battery includes design parameters, current requirements, capacity and runtime requirements, temperature requirements and safety requirements.

Critical to battery design is knowing how much voltage is needed. Voltage will measure the electrical energy. In order to know the voltage requirements we need to know the upper and lower voltage range (nominal range).

The second key knowing component of a battery is its current requirements. PDAs, MP3s and other portable devices, for the most part, utilize a constant power discharge to operate. This means that the amount of current, the battery discharges electricity to increase to maintain constant power up. So we need to know, ultimately requires the maximum current. This is important because the max current requirement will influence the necessary protection of chemistry, circuitry, wire, and capacity among others. Again we must know the current requirement over the entire nominal voltage range of the battery including start-up currents, surges (intermittent transient pulses).

Another important aspect to know about current requirements is the inert current consumption of the device. Devices, even when it shut down small amounts of current to power memory, switches and component leakage.

Knowing the third essential requirement is the necessary battery capacity and period. This determines the overall physical size of the battery. Capacity and runtime is measured in amperes. Amplifiers – or A – is an abbreviation of Ampere, a 19th Century French scientist, a pioneer in the research was current. Amps measure the volume of electrons through a wire in a second. The electric current is measured in amperes, where 1 ampere is the flow of 62,000,000,000,000,000,000 electrons per second measured!

Amp hours – or Ah – measures capacity. Ah, what is ultimately important to consumers because of their ability or amp hours that tells us how long can we expect to deliver a battery, a charge before it runs. As with all metric measurements, Amps can be used in smaller (or larger) units by adding a prefix to be divided, in this case by an “m” have the amp hour we renaming the amp hour to milli-ampere hours are: mAh; (1Ah = 1000 mAh).

When we consider the design capacity we must determine the chemical needed to ensure that the necessary runtime are met. Lithium is used because of its electrochemical properties. Lithium is a part of the alkali family of metals a group of highly reactive metals. Li reacts steadily with water. In addition to the per unit volume of lithium packs the greatest energy density and weight for this grouping of reactive metals.

Ambient temperatures are also important because the internal heat of the battery compartment dramatically affect the life of a battery. Use and storage patterns are external effect, which also affects the battery life and the responsibility of a user (for example, you can use your device in a hot car with the windows and doors, or take your device into a sauna).

A safety requirement for a battery that contains lithium requires protection circuitry to prevent the cells in battery conditions such as over charge, over discharge, high currents and short circuits or. Protected circuits consists of integrated circuits (programmed digital circuits), several field-effect transistors (FET), that the current system between two points, and resistors (two-terminal electronic component that resists the current flow, creating a voltage drop between the terminals). These circuits add cost and space to the battery pack requirements and careful placement is required in physical layouts to preserve system integrity.

Electromagnetic interference (EMI) or protection from electrostatic discharge is another safety issue. EMI, radiated or can occur throughout the electromagnetic spectrum. The primary problem with EMI is the disruption of power electronics. In wireless devices EMI can cause attenuation losses in signal strength and noise during transmission. Batteries are used as radiated sources of EMI and therefore shielding measures to take to reduce or prevent, and EMI.

Another aspect of lithium battery design is the concept of smart batteries. A smart battery stores, monitors, prevents battery and transmits critical information stored in the battery.

A smart battery will communicate with the host device through a connector to provide information about remaining capacity, battery voltage, error, cycle, internal temperature, current, and various other factors. A smart battery can have air conditioning cycle, which charge the battery fully discharge and then it will allow the internal remaining capacity value, accurate calibrated. Smart batteries often have an LED or LCD display to allow the user to charge the battery checked before use.

Lithium based smart batteries typically use coulomb counting the capacity to define the circuit monitors the capacity in and out of the battery by measuring voltage across a sense resistor means. For example 1 coulomb, the amount of electrical charge by a current of 1 ampere flows is carried out for 1 second. Coulomb counting is based on Coulomb basis Law states that the size of the electrostatic force between two point charges is directly proportional to the sizes of each charge and inversely proportional to the square of the distance between the charges is.

The review of the internal structure of a battery was extensive. I hope it gives you a basic under the hood understanding of the history of how older batteries worked.

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