Custom Battery Pack Design-Design, Manufacturers and Assembly

May 29, 2020   Pageview:161

Batteries help us to use electronics on the go when we don’t have access to grid power. In some cases, like smartphones, batteries are the sole source of power even when the phone is plugged into a power source. What an ordinary user of these devices may not know is in most cases, these batteries are a combination of more than one cell that are put together into a battery pack to form a battery that is put in the gadget.

Batteries are put in battery packs for a couple of reasons that include the following:

  • To get the required voltage to power up a given device. For instance, most of the laptops we use require 11.1 to 18 V to operate depending on the power requirements of the laptop. But the Li-ion and Li-Po cells used in these laptops have a nominal voltage of 3.7V. To get more voltage, these cells are connected in series and then put into a battery pack. For instance, a 3-cell battery will normally have a nominal voltage of about11.1V.

  • To increase the current and capacity of the batteries. If the device you’re using needs more current than 1 cell can provide, then you will have to a connect a couple of cells in parallel in order to get the desired current you need. Likewise, if you need more battery capacity than what a single cell has, you can also connect the cells in parallel to get the desired battery capacity.

How do you design a lithium ion battery pack?

In designing the battery pack for Li-ion batteries, there are several factors that you need to consider. These include the following;

Desired Voltage and Current

Lithium-cells have a nominal voltage of 3.7v and a maximum discharge current of about 1A to 2A. If you need more voltage, you will have to connect the cells in series and if you need more current, the cells have to be connected in parallel. The shape of a battery pack of the cells connected in series is obviously different from that of cells connected in series.

24V Emergency Starting Power Supply,Low Temperature Large Current
Low Temperature Large Current 24V Emergency Starting Power Supply Battery specification: 25.2V28Ah (lithium battery) , 27V300F (supercapacitor pack) Charging temperature:-40℃~+50℃ Discharging temperature: -40℃~+50℃ Starting current: 3000A

Cells connected in series may require a battery pack that has a rectangular or tube-like design having more length than width or radius. On the other hand, cells connected in parallel may need a slightly different design. In some situations, like laptop batteries, a combination of cells connected in series and those connected in Parallel may be required to get the desired voltage and current. So, the design of this kind of configuration may be different from that of the batteries connected in series or parallel.


Size and Shape of the Battery Slot on the Target Device

The battery pack has to be designed in consideration of how the battery slot of the target device was designed. This means its shape, size and position of the terminals should all be designed in line with the battery slot of the target device. So, before designing the battery pack, it is important to clearly study the battery slot of the device to avoid designing a battery that doesn’t fit into the battery slot. Or in some situations the terminals on the battery pack being miss-aligned from those of the battery slot.

The above two factors are the main things that are considered while designed the battery pack for Lithium batteries.

Low Temperature High Energy Density Rugged Laptop Polymer Battery 11.1V 7800mAh
Low Temperature High Energy Density Rugged Laptop Polymer Battery Battery specification: 11.1V 7800mAh -40℃ 0.2C discharge capacity ≥80% Dustproof, resistance to dropping, anti - corrosion, anti - electromagnetic interference

What custom battery manufacturers do you know?

If you’re designing an electronics device, you may need custom battery packs that are designed based on your product. This will require a custom battery manufacturer to help you design a battery that properly fits in the battery slot of your device. Let me share with you some of the leading custom battery manufacturers that produce custom battery packs for small and big companies

Custom Power

This company has been around since 1995 and they have capacity to design batteries of difference configurations and designs. They specialize mainly in designing custom battery packs for Lithium batteries. To get started, simply visit their website and give them your requirements to get a quote


Epec has manufacturing facilities in USA and china. They have capacity to design custom batteries for different battery technologies like Lithium-ion, lithium polymer, nickel metal hydride, nickel cadmium, lithium primary, and alkaline battery packs. So based on the device you are using, they may also recommend the best battery technology for such a device when you submit your requirements for a quote.


Unlike the above two companies, Cadex manufactures both custom batteries and their chargers. So, you get the custom designed battery and its charge if at all you need both. They have been in business since 1981. So, they have experience in designing a wide range of custom battery technologies and their chargers.

Unix Power Solutions

This is a UK based company that specializes in designing custom batteries. They have capacity to design and manufacture custom batteries with different internal chemistry based on the requirements of the customer. Over the years, they have worked with companies like LG, Samsung, Saft, Panasonic and many others to design custom batteries for their devices.


Dongguan Large Electronics Co., Ltd was established in 2002, and the headquarters located in Gaosheng Science & Technology Park, Dongguan city, Guangdong province, China, which is a national-level high-tech enterprise combining with independent research, development, production and sales of lithium ion battery pack.

How do you assembly a custom lithium ion battery pack?

After determining the number of cells and the configuration in which you are to arrange them, the next thing is connecting the cells together and putting them in a battery pack. But before putting them in the battery pack, terminals of the cells have to be connected together by spot welding them using a nickel strip. Soldering the cells directly is a little dangerous as it may have side effects to the operation of the battery in the long run.

At times when the battery gets too hot, cells with soldered terminals may experience a short circuit that may damage the whole battery and in some cases the device as well. So, it is recommended that a capacitive discharge spot welder be used to join the terminals and then pack the combined cells safely into the battery pack. The choice of material for the battery pack should depend on the target device and also what the customers prefers.  But most battery packs are made of plastic materials that are normally made by injection molding.

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