Battery basics and using batteries in electronics

Batteries are an important source of power for many electronic and electrical circuits. The word battery technically implies that there are multiple chemical cells connected together. However, independent cells are available, and widely used. They are still referred to as being “a battery” or “a single cell battery” by most electronics enthusiasts.

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Warning: This website just lists some basic properties of batteries. Always consult the manufacturer specifications/datasheet for any batteries you use and follow their guidance! There’s a high chance of damage/injury while working with batteries, so safety must always be the first priority.

First off, I want to clear something up that may be confusing. You often hear of batteries referred to as being primary or secondary. This probably won’t mean something like that there is a main battery and also a backup battery. Instead, it refers to whether batteries can be recharged or not. See below.

• Primary battery – Can not be recharged.
• Secondary battery – Can be recharged.

Basic battery properties:

The first property of a battery that we are interested in is it’s voltage. All of the circuits that we build and/or study depend on voltage to move charges (current) through the circuit. Primary factors determining battery voltage.

• Chemistry – Determines the cell nominal voltage, which is likely the average voltage.
• Number of cells – Connecting cells in series adds up their voltages for a “total voltage”.
• Nominal voltage – A cell’s voltage goes down as it is being used. And, if it is rechargeable, the voltage rises while being charged. The nominal voltage is about the average voltage you can expect a cell to be through a full cycle.
• State of charge (SOC) – Percentage of charge a battery is currently at. Fully charged = 100% and whatever voltage is considered fully discharged = 0%.
• Capacity – Amount of current a specific battery can be expected to provide during a certain voltage change (discharge) under normal circumstances.

Typical cell nominal voltages by chemistry: Often varies, so verify your particular battery voltage

• Alkaline cell 1.5V – the common 9V alkaline is 6 series cells, 12V alkaline is 8 series cells.
• Lithium/li ion cell – 3.6V – Some manufacturers prefer to call them 3.7V cells
• Lead acid cell – 2V, it is important to keep them charged above 2.1V as soon after discharging below 2.1V as possible. Gas powered vehicle batteries are usually nominally 12V, having 6 series lead acid cells within them.
• Nickle NiCd (NiCad)/NiMH (Nickle metal hydride) – 1.2V – Some manufactures prefer to call them 1.25V

Another major property of a battery that we are interested in, is how much total charge it can deliver. This is called capacity.

There are a lot of battery options out there. So, it is important to research the manufacturer specifications/datasheets to ensure the batteries you are looking at will meet your needs!

This is a new page that will be updated later!