Learn how to assemble batteries to increase voltage or capacity/current.
How to Configure Series and Parallel Batteries
The operating voltage range of a Battery Pack commonly used to supply electronic devices such as laptops, power banks, Jump-Starters, Drones, etc., is determined by several battery cells arranged in series, the total voltage is the sum of each battery cell voltage. Meanwhile, battery cells arranged in parallel can increase the total capacity of the Battery Pack.
The unit of voltage is volt (V), current is ampere (A), capacity is ampare hour (Ah), while power is watt (W) the product of voltage and current.
Battery Packs can consist of a combination of series and parallel connections. A typical laptop battery has four 3.6V Li-ion battery cells in series to achieve a working voltage / operating voltage of 14.4V and two battery cells in parallel to increase the capacity from 2400mAh (2.4Ah) to 4800mAh (4.8Ah). This configuration is called 4S2P (4 series 2 parallel). Foil insulation between battery cells is useful to prevent short circuits.
It should be noted that, the selection of battery cell types must be uniform between brands, sizes, voltages, and capacities/currents (Ah), and never mix with different specifications, because it can cause imbalance. Each battery cell affects each other in the arrangement, if one of them is weak it can break the performance of the Battery Pack, or if one of them is stronger it can cause ripple current (unstable DC current).
Chain links represent the series arrangement of battery cells.
Weak battery cells are not damaged all at once, but there are symptoms of dropping first. When Charging ON, weak battery cells experience longer charging before other normal cells, this condition is not effective and inefficient, because because of one or several weak battery cells, other normal cells do not get maximum / full Charge. So, if your laptop battery drops, it is not necessarily that all battery cells are damaged / dropped, but rather there is one or several that are damaged / dropped, thus inhibiting the charging of cells that are still good.
Life Cycle Performance of Uniform Battery Packs VS. Mixed Battery Packs.
Single Battery Cell Applications
Single cell configuration is the simplest battery, the battery cell does not need uniformity and does not need a series / safety circuit. An example of a single cell Li-ion battery, generally found in mobile phones or tablets with a voltage of 3.6V, in 1.5V alkaline batteries for wall clocks, etc.
Meanwhile, the nominal voltage of nickel-based battery cells is 1.2V, alkaline 1.5V, silver-oxide 1.6V, lead acid 2V, primary lithium ranges from 3V-3.9V, Li-ion 3.6V, Li-phosphate 3.2V, Li-titanate 2.4V, Li-manganese and other lithium-based systems often use 3.7V cell voltage and high power. The reason is that the smaller the internal resistance of the battery cell, the higher the voltage and power (Ohm's Law Principle).
Series Battery Cell Applications
Portable equipment usually requires higher voltage, therefore battery packs are used with two or more battery cells connected in series. The image below is an example of a battery pack with 4 battery cells, each with a voltage of 1.2V nickel-based. Known as 4S (4Series), to produce 4.8V. For comparison, you can use battery cells with other materials / bases, please observe the difference in voltage.
Battery Cell Series Circuit
The image below illustrates a battery pack with 3 battery cells with 1 drop cell, which only produces 0.6V instead of the full 1.2V. When getting pressure charging working voltage, then when the battery reaches the maximum charging limit, it does not last long and the battery immediately drops with the message "Battery Low".
Battery Drop Cell Series Circuit
Drone and remote control batteries for hobby require high current loads, and often exhibit unexpected voltage drops, should one of the battery cells in the pack fail. The figure above illustrates the maximum current of normal battery cells being wasted just to stress the weak battery cell, only for the weak cell to reach its proper working voltage, and the result is wasted, even until the normal battery cells run out of power.
Parallel Battery Cell Applications
If higher current is required to supply your electronic devices, but there are no suitable battery cells available on the market, then the step you can take is to arrange several battery cells in parallel. Most chemical batteries with parallel configurations have few side effects. The figure below illustrates four cells connected in parallel in a P4 arrangement. The voltage of the pack is illustrated as 1.2V, but has a 4x runtime (capacity).
Battery Cell Parallel Circuit
A battery cell that experiences a drop / increase in resistance will not mean too serious in a parallel configuration, unlike a series circuit that can have a systemic impact / dysfunction / total death. But the battery cell drop will reduce the total power.
It is the same as 6 horses pulling a chariot, even if one horse dies, the remaining 5 are still strong enough to pull the chariot, even though the load carried by each horse becomes a little heavier, so they quickly get tired.
Drop Battery Cell Parallel Circuit
A dropped battery cell in a parallel configuration will not reduce the voltage, but will reduce the runtime / capacity / power. Meanwhile, a shorted cell can cause overheating and cause a fire.
Parallel & Series Combination Battery Cell Applications
The combination of series and parallel configuration is shown in the figure below 2S2P (2 Series 2 Parallel), this allows flexibility in achieving the desired voltage and current without neglecting the standard size of the battery cell. The total power illustrated in the figure is four 1.20V x 1000mAh = 4.8Wh.
Battery Cell Series-Parallel Combination Circuit
Li-ion capability is suitable for series-parallel combination configuration, but special monitoring is needed to stay within the working voltage tolerance limit. IC components are needed to control this, one of which is the Regulator IC.