Pictured above is a typical notebook battery, in this case an IBM ThinkPad A30 and A31 Series Battery. Notebook batteries from other major OEMs such as Sony, Dell, HP, and Toshiba have very similar appearance, construction, and operation.

Learn more about notebook battery construction, circuit diagram, chemistry, compatibility, care & maintenance, technical specifications, problem solving, and recycling.

Construction
Notebook battery construction is relatively simple. Each battery is made up of a number of individual "cells". Cells themselves are batteries, typically in cylinder form, rated at 3.6V or 3.7V, depending on the manufacturer. Cells are placed in series create the overall notebook battery output rating in Volts DC. Using Ohm's law, batteries in series are additive, so the overall rating is simply the sum of the number of cells in series. Three cells in series produce 10.8V or 11.1V; four cells in series produce 14.1V or 14.4V. The 10.8V, 11.1V, 14.1V, and 14.4V ratings compose the universe of output ratings for most all notebook batteries.

Battery run-time is proportional to the number of parallel rows of cells in series. Again using Ohm's law, the more parallel rows, the greater available amperage thus increasing run-time. Looking inside the Thinkpad battery, we see six cells, a pair of three cells in series.

Besides the cells, a notebook battery contains circuitry for monitor and control functionality such as over temperature protection. The entire package is sealed within a plastic enclosure with mating connector for designated system. Although all notebook batteries are of similar construction, they are not interchangeable between laptop manufacturers due to size and shape, output rating, and monitor/charging interface. IBM, Sony, Dell, HP and Toshiba all have different control circuitry, connectors, and shapes. Indeed, even commonality within a single brand across product lines is rare. HP probably does the best job of using a single battery design for many different notebook models.