Lithium Battery Pack Assembly Services for OEMs

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Lithium Battery Company provides lithium-ion battery pack assembly for OEM programs. We build packs to our own designs, to modified catalog designs, or to your drawings and bill of materials. Every build follows a controlled specification with inspection points and end-of-line test records. We've been building custom lithium packs since 2014, with hundreds of thousands produced for OEM programs.

Assembly programs start at 25 units for custom and build-to-print work, and catalog packs start at 10 units.

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Assembly programs we take on

  • Custom pack assembly. We design the pack around your equipment, then assemble it. See custom lithium-ion battery packs.
  • Build-to-print assembly. You own the design; we assemble to your drawings, BOM and test limits, and raise deviations for your approval. See build-to-print battery packs.
  • Modified catalog packs. Start from a reference design and change capacity, connectors, BMS communications or the enclosure.
  • Second-source assembly. Add a second assembler for a pack you already buy, or replace a supplier that's struggling. See battery supplier replacement.

What lithium battery pack assembly involves

Pack quality is decided on the line as much as in the design. These are the steps we plan and control for each program:

  1. Cell receiving and matching. Cells are checked against the approved cell specification, and grouped so that cells in the same parallel group and string are matched on voltage and internal resistance. Mismatched cells age unevenly and shorten pack life.
  2. Module build. Cells are fixed in holders or frames and joined with interconnects or busbars sized for the pack's continuous and peak current. The joining method is chosen for current, vibration and repeatability.
  3. Insulation and protection. Insulating barriers, cell-to-enclosure clearances and fusing are built to the drawing, because a pack's short-circuit risk lives in these details.
  4. BMS integration. The battery management system is connected to every series group with correct sense-wire routing, and its firmware, protection limits and communications are set to the program's approved configuration. See battery management systems.
  5. Harness, connectors and enclosure. Power and signal harnesses, connectors, thermal pads, potting or foam where specified, and the enclosure or wrap, with torque and routing checks.
  6. End-of-line testing. Each pack is tested against the program's acceptance criteria. Typical checks are open-circuit voltage, internal resistance, BMS protection and communication function, charge and discharge checks, and labeling. Test records are kept per pack or per lot.
  7. Packaging and shipping preparation. Packs are prepared for transport as lithium batteries, at the state of charge and with the documentation the shipment requires.

Quality controls built into assembly

  • A frozen specification. The approved BOM, drawings, firmware version and test limits are fixed before volume builds.
  • Golden samples. A reference pack from the approved build to check later lots against.
  • Inspection points. Defined checks at receiving, during assembly and at end of line, with records.
  • Traceability. Cell lots and BMS firmware tied to pack serial numbers or lots, so a field issue can be traced.
  • Change control. No silent substitutions. Component, firmware or process changes go through you first.

For a deeper look at how to judge any assembler, see battery supplier qualification.

From first article to volume

Most programs start with a prototype or pilot lot to confirm fit, function and the test process, then move to scheduled production. See OEM battery pilot production and small-batch lithium battery production. Lead times run from weeks to months depending on the cells, design scope and validation, and your quote confirms them.

LFP and NMC pack assembly

We assemble packs in both LiFePO4 (LFP) and NMC chemistries. LFP suits long-life, high-cycle equipment such as industrial machines, AGVs, telecom backup and energy storage. NMC suits weight-sensitive equipment. See LFP battery packs and NMC battery packs.

What to send for an assembly quote

For build-to-print: drawings, BOM with approved cells and BMS, firmware, test limits and acceptance criteria, labeling, packaging requirements, first-order quantity and annual volume. For custom assembly: the application, voltage window, load, runtime, space, charger, environment and volumes. Start your assembly quote.

Frequently asked questions

Do you assemble battery packs to our own design?

Yes. We assemble build-to-print packs to your drawings, BOM and test limits, and raise any deviation for your approval before it goes into production.

What testing is done on each assembled pack?

Each pack is tested against the program's acceptance criteria. Typical end-of-line checks are open-circuit voltage, internal resistance, BMS protection and communication function, charge and discharge checks, and labeling, with records kept per pack or per lot.

What is the minimum quantity for a battery pack assembly program?

Custom and build-to-print assembly programs start at 25 units. Catalog packs start at 10 units.

Can you assemble both LiFePO4 and NMC packs?

Yes. We assemble LiFePO4 (LFP) and NMC lithium-ion packs and can recommend a chemistry from your load, runtime, weight and temperature requirements.

Can you become a second source for a pack we already buy?

Yes. We review the incumbent pack and its documentation, then plan a controlled transfer with validation before volume builds.

Request a custom battery quote Send a build-to-print package