Battery Measurement

BMS Lithium Ion Battery Internal Resistance

Internal resistance results are meaningful only with a stated ACIR/DCIR method, SOC, temperature, rest, level, contacts, instrument and baseline. A single BMS value is not a universal SOH verdict.

By Batteries To Spec Technical Editorial Team · Updated September 3, 2026

Compact custom lithium-ion battery pack with connector
Direct answer

Resolve the decision before selecting a model.

Internal resistance results are meaningful only with a stated ACIR/DCIR method, SOC, temperature, rest, level, contacts, instrument and baseline. A single BMS value is not a universal SOH verdict.

VoltageA state variable, not proof of capacity
CapacityRequires a controlled energy or charge test
ResistanceMethod- and condition-dependent
SafetyStay within equipment and personnel ratings

Practical review checklist

01Method

Define the quantity, instrument and test method.

02Conditions

Control SOC, temperature, rest, load and contacts.

03Boundary

Separate cell, module and complete-pack results.

04Decision

Compare with a model baseline and repeatability criteria.

What to request from a supplier

Ask for a model-specific specification, electrical and mechanical limits, BMS or interface definition, current test evidence, document list, sample plan and change-control route. Keep open items visible rather than replacing them with a generic promise.

What this page does not prove

It does not certify an unnamed battery, approve a host system, guarantee a carrier route or establish a quotation without the exact model, destination and date.

Primary references

Sources and scope

Standards, carrier rules, prices and import requirements change. Confirm the current edition and the exact product, route and market before acting.

Project RFQ

Turn the decision into a reviewable battery specification.

Send the application, voltage window, load, runtime, space, interfaces, environment, quantity, destination and required documents.