A portable device that requires high power is generally powered by a LiPo battery pack in which two or more lipo battery cells are connected in series. If a high voltage battery is used, the size of the conductors and switches can be made small. Usually we will use 24V and 12V batteries. But the 24V battery is expensive, and it produces more arc on the switch than the 12V battery. Another problem with using a high-voltage battery pack is that it is possible to experience a failure of a certain battery in the battery pack. It’s like a chain, the more batteries are connected in series, the higher possibility of that will be. As long as there is a problem with one of the batteries, its voltage will decrease. Finally, the “disconnected” battery may interrupt the delivery of current. However, It is not easy to replace the “bad” battery, as the old batteries and new ones are not matched to each other. In general, the capacity of new batteries is much higher than that of older batteries.
In fact, regardless of the difference between the series and parallel connection of the battery, we still have to ensure the consistency of the LiPo battery cells in series and parallel connection. So that different battery cells can be separately charged without being bothered.
So what are the differences between them?
Battery in series:
It means that the battery is connected end to end. That is, the positive pole of the first battery is connected to the negative pole of the second battery, and the positive pole of the second battery is connected to the negative pole of the third battery, and so on;
The voltage after series connection is equal to the sum of each Li-Polymer battery cell voltages, and the capacity is equal to the current flowing through each battery;
A damage in any lithium battery cell will make the entire lithium battery pack unusable or lead to the voltage drop;
Series connection can increase the total voltage.
It means that the head of the first battery is connected to that of the second battery, and the tail is also connected to that of the second battery. That is, the positive poles of all the batteries are connected together, meantime, the negative poles of all the batteries are connected.
The final voltage is equal to the individual battery voltage and the capacity is equal to the sum of the battery capacity.
Although the battery life of the battery pack is enhanced, the damage caused by the short-circuit current is more serious;
Parallel can increase the total current and capacity.
The difference between battery parallel and series is mainly the difference in voltage and capacity.
Take an example of a Lithium polymer battery 3.7V 3000mAh, for two of the same LiPo batteries, if it is two cells in series, then the battery pack model is: 7.4V /3000mAh, if it is two cells paralleled, the model will become: 3.7V/6000mAh. When connected in series, the voltage will increase while the capacity does not change. When connected in parallel, the capacity will increase while the voltage keep same. But the batteries we often use are always connected in both series and parallel circuits, such as: three series and four.
- When the batteries are connected in parallel, the voltages are the same everywhere, that is, Ua=Ub=Uc=Uo; the capacity/current is the sum of the currents of the respective batteries, that is, Io=Ia+Ib+Ic.
The battery is connected in parallel for the case where the voltage keeps same while the current/capacity needs to be increased.
- When the batteries are connected in series, the currents are the same everywhere, that is, Io=Ia=Ib=Ic; the voltage is the sum of the voltages of the respective batteries, that is, Uo=Ua+Ub+Uc.
The battery is used in series for applications where the capacity keeps the same while the voltage needs to be increased.
Whether in series or in parallel, the output power of the battery pack will absolutely increase.