How to select a custom battery pack: 6 steps from requirement to solution

Why does selection start with how the product is used?

How the product is used decides how the pack is used: constant float charging for backup, or high-current cycling every day; a temperature-controlled indoor environment, or an outdoor device exposed to seasonal swings; cycled once a day, or only called on in an emergency. The same electrical specification leads to a very different thermal and mechanical design in energy storage versus a low-speed vehicle.

Selection therefore starts not from capacity, but from where, how and how often the device operates. That sets the trade-off direction for every parameter that follows, and is the basis on which we pick a more cost-effective solution. The more specific your usage description, the closer our selection lands to production conditions.

Which electrical parameters need to be confirmed?

Electrical parameters include system voltage, nominal capacity, continuous and peak current, charging method and the working voltage range. Voltage and capacity come from the platform, current from the load, and the charging method from how often the device is used. Once you give us the rated and peak requirements, we fix the series/parallel layout, protection parameters and chemistry direction, so nothing is guessed and reworked later.

• System voltage and nominal capacity
• Continuous and peak current
• Charging method and charging current
• Working voltage range and protection requirements

How is the form factor decided?

The form factor starts from installation space, weight limits and the interface. The battery compartment or mounting position sets the size boundary; from there we choose a prismatic, cylindrical or pouch direction and complete the mechanical and mounting design. Form is not only appearance — it sets the heat path, centre of gravity and cable routing, so it is settled together with the electrical parameters rather than afterwards.

When should certification and the target market be confirmed?

Certification and the target market should be settled at the design stage, not before shipment. Different markets demand different access items, and export transport compliance documents belong to lithium-ion packs only. Confirming early avoids rework and delays from re-certifying after mass production.

Tell us the target market and the model; we review the applicable items, provide existing certificates and reports directly, and take on any additional items with a plan confirmed together with you.

At which step does cost enter the assessment?

Cost runs through every step, but the focused evaluation happens once the electrical and mechanical side is largely fixed. With the boundaries clear, we can pick a more cost-effective chemistry and structure while still meeting performance, instead of trading away safety to save cost.

The evaluation is based on your target cost range and order volume, and is confirmed with you in a formal quotation — there is no surprise adjustment after selection.

What do we check at solution confirmation?

At confirmation we lay out the selection result, series/parallel layout, form factor, certification items, lead time and sampling plan for you to check. This step consolidates everything confirmed earlier into one workable document, so no detail is lost in a verbal agreement.

After confirmation, samples are made to the same technical and inspection standards as mass production, so production quality matches the sample you approved. Design, manufacturing and delivery are handled by the same team, so every issue can be traced to its owner.

How is the selection work divided between us?

The division of work is simple: you state the usage conditions, we return the selection proposal. Tell us the application, voltage and capacity, current, temperature environment, size and target market, and we return a proposal and recommendation close to production conditions. This puts the professional judgement on our side, so what you receive is a result you can assess and verify directly.

How do I state the requirements clearly?

Stating requirements clearly means giving measurable information rather than impressions. Instead of “longer range”, give the expected voltage, capacity and working time; instead of “durable”, state the charge/discharge frequency and the usage environment. Prepare these six items — application, voltage and capacity, current, temperature environment, size and target market — and we can return a selection direction quickly.

What is the next step after receiving the selection proposal?

After receiving the proposal, you check the parameters, certification items and lead time, then move into the sampling stage once confirmed. Samples are made to the same technical and inspection standards as mass production, so production quality matches the sample you approved. If requirements change after confirmation, we re-assess the impact rather than forcing the old proposal onto the new requirement.

After sample approval comes production scheduling. Scheduling and lead time depend on the model, quantity and current production load; we give the timing together with the confirmed solution, and projects with firm deadlines should be communicated early.

How do I avoid common problems during selection?

The most common problem is incomplete parameters: voltage without current, capacity without space, temperature without whether low-temperature charging is needed. Missing information makes the design bounce back and forth and stretches the timeline. Give the six items together right at the outset of the conversation and we return a proposal close to production conditions in one pass.

Another problem is leaving form factor and certification for later. Form affects heat, balance and structure, while certification affects lead time and cost — changing them later costs more. Both should be confirmed with the electrical parameters at the design stage, not patched in after the pack is built.

Another issue is conflating selection with quotation. Selection fixes the design direction, while quotation confirms price after the design is set — they come in sequence. We advance step by step, and you receive a verifiable result at each stage, with no quoting before the direction is fixed.

If the requirement is still changing, say so early. The later a change comes, the more stages it touches. We separate changeable and fixed items at the design stage to reduce later rework.

Where you are unsure, just state your concern. We explain the impact and then recommend, rather than asking you to decide without a basis.

One last reminder: a selection proposal is not a one-shot fixed document — it closes up as the requirement clears up. As parameters, form, certification and lead time are confirmed one by one, the proposal takes shape. Keeping a verifiable record at every step avoids rework from a forgotten verbal agreement.