Batteries Series and Parallel is the act of connecting two or more batteries together. By connecting the two or more batteries in either series or parallel, you may increase the capacity and voltage, allowing for more power and/or energy, and therefore the equipment will last longer. Before we can investigate the differences in wiring between series and parallel batteries, we must first understand how to connect them. And what precisely does each of these phrases imply.
Parallel connection
The battery capacity will be increased, the voltage will remain constant, and the internal resistance will decrease.
Lithium battery Parallel connections usually involve connecting two or more batteries together to improve the battery bank’s amp-hour capacity while maintaining the same voltage. To link batteries in parallel, connect the positive terminals with one cable and the negative terminals with another until you achieve the necessary capacity.
The example below shows four 100 Ah batteries linked in parallel. The negative connection from the first battery is linked to the negative terminal of the second. Likewise, the positive terminals of both batteries are linked. The overall system voltage is 12 volts, and the total capacity is 400 mAh.
Connecting batteries in parallel or series.
The battery voltage will be raised, the capacity will remain constant, and the internal resistance will rise.
Lithium battery series connections usually entail connecting two or more batteries together to enhance the voltage of the battery system while maintaining the same amp-hour rating. Before connecting, please Keep in mind that in series connections, each battery must have the same voltage and capacity rating, otherwise you risk harming the battery. To connect two batteries in series, connect the positive terminal of one to the negative terminal of the other until the necessary voltage is reached. When charging batteries in series, use a charger that matches the system voltage. To prevent battery imbalance, we suggest charging each battery independently using a multi-bank charger.
The example below shows four 100 Ah 12V batteries linked in series. As you can see, the positive terminal of the first battery is linked to the negative terminal of the second. Thus, the entire system voltage is 48 volts, with a total capacity of 100 Ah.
Wiring Batteries in Series
Almost all lithium batteries are packed via battery cells, much as every organ in our body is formed of cells. The battery internal structure is connected in series and parallel before our factory installs the whole battery pack into the case. The 300Ah 12.8Volts LiFePO4 lithium battery is packed using 4S3P, which means that four 3.2V100Ah LiFePO4 battery cells are connected in series and three 3.2V100Ah LiFePO4 battery cells are connected in parallel, resulting in a 300Ah 12.8Volts LiFePO4 battery. However, it is not enough since many systems are 36V, 48V, 72V, even for golf carts, saitboats, and so on. So there must be a problem: what is the wiring difference between batteries in series and parallel connections?
Notices before connecting batteries in series or parallel.
Do not connect batteries of different chemistries in series or parallel. For example, do not link SLA batteries to LiFePO4 batteries. Whichever battery dies first (in this case, it will most likely be the SLA battery) will reduce the performance of the other(s), resulting in reduced usage time. If one continues to use this mix-and-match system, both batteries will ultimately become so imbalanced (more on cell balancing below) that they will be rendered worthless.
Do not connect various brands of lithium iron phosphate lithium ion battery packs, different capacities, or new and old lithium ion batteries, and only use batteries with the same performance. When the battery power is low, replace all of them. When connecting lithium-ion battery packs in series, use the same kind of battery. Pay care to the battery’s polarity. If one battery’s polarity is reversed, the voltage of the whole string is lowered rather than increased.
Do not connect a fresh lithium battery to an old battery; there may be leakage, zero voltage, and other issues. This is because, during the charging process, the capacity discrepancy causes certain batteries to be overcharged while others are not completely charged. During discharging, certain high capacity batteries are not entirely depleted, whereas low capacity batteries are over-discharged. In such a vicious spiral, the battery is damaged and leaks, resulting in low (zero) voltage.
General lithium iron phosphate battery packs are connected in series and parallel to match lithium ion battery cores. The partnering standard specifies a lithium ion battery core voltage difference of ≤10mV, an internal resistance difference of ≤5m, and a capacity difference of ≤20mA.
It’s also advisable to utilize batteries with equal voltage and amp hour ratings. The simplest method to achieve this is to connect two (or more) variants of the same battery. Things may become complicated when connecting up batteries with various battery management system components, and the possibilities are rather diverse. Regardless of the variations in those results, you will often wind up with highly imbalanced cells, as in the preceding example.
How to charge a battery in series vs parallel?
Charging Lithium Batteries in Series
Currently, lithium batteries are charged in series, owing to their simple construction, cheap cost, and ease of implementation. However, due to differences in capacity, internal impedance, aging characteristics, and self-discharge performance, while charging a lithium battery in series, the battery cell with the lowest capacity is completely charged first, and the other battery cell is not yet entirely charged. If you continue to charge in series, the fully charged battery cell may become overcharged.
Overcharging a lithium battery may harm its performance and perhaps cause an explosion and casualties. To avoid battery cell overcharging, lithium batteries are integrated with a Battery Management System (BMS). The Battery Management System includes overcharge protection for each lithium battery cell, among other features. When charging in series, if the voltage of a single lithium battery cell reaches the overcharge protection voltage, the battery management system will turn off the entire series charging circuit and stop charging to prevent the single lithium battery cell from being overcharged, rendering other lithium batteries unable to be fully charged.
Charging Lithium Batteries in Parallel
In parallel charging of lithium batteries, each lithium ion battery requires an equalizing charge; otherwise, the performance and longevity of the whole lithium ion battery pack would suffer. Common charging equalization methods include continuous shunt resistance equalizing charge, on-off shunt resistance equalizing charge, average battery voltage equalizing charge, switch capacitor equalizing charge, step-down converter equalizing charge, and inductance equalizing charge, among others.
After the lithium ion batteries are connected in parallel, a charging protection chip will be installed to safeguard the lithium batteries during charging. Lithium battery makers have completely analyzed the lithium battery’s changing properties before beginning manufacturing. The following requirements for current design and battery selection are critical, therefore users must carefully follow the directions for charging parallel lithium batteries step by step to prevent any harm from wrong charging.
Can Yibai energy lithium batteries be linked in series or parallel?
To support the batteries parallel or series connection, the durable current and voltage of BMS and battery need to be increased. For example, if we connect the four units 12.8V100Ah LiFePO4 batteries in series, the system will be 51.2V100Ah system, the durable voltage and voltage typically need to be increased, which will obviously increase the cost. In order to reach the different applications with the most favorable price, we typically recommend a maximum of four batteries in To achieve a 48V or greater voltage system, we designed the KH-LFP-SC series (Series capable battery series) to perform the purpose. For other requirements, such as 60V or 72V systems, we may create a bespoke design based on the appliance’s system requirements.
Additional questions concerning the battery in series and parallel. Contact the Yibai energy team for specific requirements.