![]() Li-ion is 3.6V Li-phosphate is 3.2V and Li-titanate is 2.4V. Primary lithium batteries range between 3.0V and 3.9V. The nominal cell voltage for a nickel-based battery is 1.2V, alkaline is 1.5V silver-oxide is 1.6V and lead acid is 2.0V. Other uses of a single cell are wall clocks, which typically use a 1.5V alkaline cell, wristwatches and memory backup, most of which are very low power applications. Typical examples are mobile phones and tablets with one 3.60V Li-ion cell. The single-cell configuration is the simplest battery pack the cell does not need matching and the protection circuit on a small Li-ion cell can be kept simple. Cells in multi-packs must be matched, especially when used under heavy loads. On discharge, the weak cell empties first and gets hammered by the stronger brothers. On charge, the low cell fills up before the strong ones because there is less to fill and it remains in over-charge longer than the others. An analogy is a chain in which the links represent the cells of a battery connected in series ( Figure 1).įigure 1: Comparing a battery with a chain.Ĭhain links represent cells in series to increase voltage, doubling a link denotes parallel connection to boost current loading.Ī weak cell may not fail immediately but will get exhausted more quickly than the strong ones when on a load. This is especially critical in a series configuration because a battery is only as strong as the weakest link in the chain. It is important to use the same battery type with equal voltage and capacity (Ah) and never to mix different makes and sizes. Most battery chemistries lend themselves to series and parallel connection. Insulating foil between the cells prevents the conductive metallic skin from causing an electrical short. Such a configuration is called 4s2p, meaning four cells in series and two in parallel. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh. Some packs may consist of a combination of series and parallel connections. Parallel connection attains higher capacity by adding up the total ampere-hour (Ah).
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