How to Customize a Lithium UPS Battery System

Customizing a lithium UPS battery system involves more than selecting the right battery capacity. For OEMs, UPS integrators, data center operators, and industrial equipment manufacturers, the battery may need to match specific electrical, mechanical, communication, and environmental requirements.

This guide explains what information to prepare, what can be customized, how BMS integration works, and what to include in a custom UPS battery RFQ.

What Information Do You Need to Customize a UPS Battery?

Before designing a custom battery, the supplier needs to understand both the UPS and its application.

For replacement projects, also provide the existing battery model, voltage, capacity, dimensions, connectors, and available UPS documentation.

Battery sizing should be based on the actual load, backup requirement, efficiency, operating conditions, and engineering margins. For detailed sizing calculations, see ACE Battery's guide on how to calculate UPS battery size.

Sizing determines how much battery is required; customization determines how that battery is designed to work with the UPS and application.

What Can Be Customized in a Lithium UPS Battery System?

A custom UPS battery can be configured across several areas:

Power, Energy, and Scalability

A UPS battery must satisfy both power and energy requirements.

Battery energy determines how long the UPS can support the load, while power capability determines whether the battery can deliver the required load during the backup period. A battery may have sufficient kWh capacity but still be unsuitable if its discharge power or voltage range does not match the UPS.

For higher-power applications, ACE Battery's U300/U400/U500 lithium UPS cabinet supports 8–12 modules per cabinet, with 600A, 800A, and 1000A frame-current options. The platform can be configured for approximately 200 kW to 500 kW UPS applications, with 2–8 cabinets connected in parallel for larger or expandable systems.

This modular approach allows the battery architecture to be configured around the project's power, energy, installation, and future expansion requirements.

How Does BMS Integration Work with a UPS?

The BMS is a critical part of a custom UPS battery system.

It can monitor cell and pack voltage, current, temperature, SOC, SOH, and fault status while managing functions such as overvoltage, undervoltage, overcurrent, short-circuit, charging, discharge, contactor, and pre-charge protection.

For UPS integration, the BMS may also need to communicate with the UPS through CAN, RS485, Modbus, or a proprietary protocol.

For a standard replacement, an existing BMS configuration may be sufficient. For an OEM UPS platform or proprietary system, the BMS hardware, firmware, parameters, or communication mapping may require customization.

If available, provide the UPS communication protocol, register map, or existing battery communication documentation during the initial evaluation. This allows the supplier to assess compatibility before prototype development.

What Is the Custom UPS Battery Development Process?

A typical customization project follows five stages:

1. Requirements
Define UPS, battery, mechanical, communication, environmental, and compliance requirements.

2. Technical Evaluation
The supplier evaluates voltage, current, power, capacity, dimensions, BMS, communication, and protection requirements.

3. System Design
The battery architecture, modules, BMS, protection system, connectors, and enclosure are defined.

4. Prototype and Validation
An engineering sample is developed and tested for electrical, communication, mechanical, thermal, and protection requirements.

5. Production
After validation, the design moves into pilot production and then repeatable mass production.

For OEM and ODM projects, this process is particularly important because the battery needs to be consistently reproduced across future production orders.

What Should You Include in a Custom UPS Battery RFQ?

A requirement such as “100 kWh lithium battery for UPS” is usually not enough for a custom project.

Use this checklist when preparing an RFQ:

UPS

• UPS model and rated power

• DC bus voltage and operating range

• Charging requirements

• Communication interface

Battery

• Required backup time

• Continuous and peak load

• Discharge power/current

• Target capacity or usable energy

• Lifetime requirements

Mechanical

• Maximum dimensions

• Rack/cabinet configuration

• Mounting and connector requirements

BMS & Communication

• Protocol and interface

• Required data points

• Alarm and protection requirements

Environment & Compliance

• Operating temperature

• Humidity and altitude

• IP requirements

• Required certifications

Project

• Prototype quantity

• Initial order quantity

• Expected production volume

• Target production schedule

Providing these details early helps the manufacturer assess technical feasibility, customization requirements, engineering effort, and production needs more accurately.

When Do You Need a Custom or OEM/ODM UPS Battery?

A standard battery may be sufficient when the UPS already defines a compatible battery configuration and communication interface.

A custom solution becomes more appropriate when the project involves:

• Non-standard voltage or power requirements

• Specific backup-time requirements

• Limited installation space

• Custom rack or cabinet dimensions

• Proprietary UPS communication

• Customized BMS functions

• Integration into existing equipment

• Project-specific certifications

For OEMs and system integrators, OEM/ODM is particularly relevant when the battery becomes part of their own equipment platform or needs to be produced repeatedly.

In these projects, the supplier should be able to support engineering design, BMS and communication integration, prototyping, validation, and scalable production—not simply supply standard battery packs.

Start Your Custom UPS Battery Project

A custom lithium UPS battery should be designed around the complete UPS and application—not simply a target kWh value.

If you have a UPS model, existing battery specification, equipment design, or project requirements, share them with ACE Battery. Our team can evaluate the electrical, mechanical, BMS, communication, and system-integration requirements and determine an appropriate customization approach.

Looking for a custom lithium UPS battery system for a UPS, data center, industrial application, or OEM platform? Contact ACE Battery to discuss your requirements.