Cells store and supply the energy, and their chemistry sets the ceiling for everything else: capacity, continuous discharge, cycle life, and operating temperature range. A pack built from high-drain cells behaves nothing like one built for maximum runtime, even at identical voltage.

High-current applications such as power tools and robotics typically call for a cell like the Sony VTC6, rated for 30A continuous discharge. Runtime-driven designs — remote monitoring, wildlife cameras, portable instruments — favour a high-capacity cell such as the Sanyo NCR18650GA. If you already know your chemistry, you can order lithium-ion battery cells in batch quantities and assemble in-house.

The BMS monitors voltage, current, and temperature to protect the cells and optimize performance. It cuts off charge and discharge outside safe limits, balances cells so one weak group cannot drag down the pack, and on smarter designs reports state of charge and fault codes back to the host device.

Matching the BMS to the pack is not optional — series count, continuous and peak current, balancing strategy, and communication protocol all have to line up with the cells and the application. It is the single most common source of trouble in packs designed without engineering support.

Nickel strips and bus bars electrically connect the cells within the pack, forming the series and parallel groups that produce the target voltage and capacity. Their cross-section has to be sized for the pack's peak current: undersized interconnects add resistance, waste energy as heat, and become a hot spot long before the cells do.

Higher-current builds move from thin nickel strip to layered strip or solid copper bus bars, with welds validated for consistency across every joint.

Wiring and connectors deliver power to the device and enable safe charging. Gauge is chosen for continuous current and voltage drop; the connector is chosen for mating cycles, locking, polarity protection, and — in medical and industrial equipment — the certifications the finished product has to carry.

Insulation and fuses protect against short circuits and improve overall safety. Barrier films, cell holders, and fish paper keep conductors apart when the pack is dropped or vibrated; fuses — at pack level or on individual parallel groups — interrupt fault currents before they can propagate.

This is the layer that separates a pack that passes shipping and safety testing from one that does not.

The enclosure shields the battery pack from impact, dust, moisture, and environmental conditions, while holding every internal component in a fixed, repeatable position. It also defines how the pack mounts, seals, and dissipates heat — which is why enclosure design and cell layout are decided together, not in sequence.

Why the system matters more than the parts

Each component plays a critical role in ensuring a battery pack is safe, reliable, and built to perform in demanding applications. Specified in isolation they rarely add up — the cell choice sets the current, the current sizes the interconnects, the interconnects and layout drive thermal behaviour, and thermal behaviour dictates sensing and enclosure design. Good packs are designed as one system.

The same logic applies across chemistries. For stationary applications, see why LiFePO4 batteries are a strong choice for data center backup power, or learn more about our engineering and certification process.

Custom battery packs are what we do best

Whether you are developing a medical device, robotics platform, industrial equipment, or another battery-powered product, we can help design a solution tailored to your application. Start from a pre-configured battery pack, shape one yourself in the Battery Builder, or hand us the spec and let our engineers take it from there.

Buying cells rather than packs? Use the loose cell quote form — minimum order 50 units.