Battery life forecast

Enter your battery's data and measurements and obtain an indicative diagnosis of its state of health (SOH) and estimated remaining life according to the Best Practices criteria and the IEEE and IEC standards for each chemistry: capacity (SOH-C), internal resistance (SOH-R), unit voltages, temperature, electrolyte, insulation and age.

Indicative tool. An exhaustive battery diagnosis must be carried out by a qualified AMPERIS engineer or, where applicable, an engineer qualified by the battery manufacturer.

01 · The battery

Technology Determines the standards, tolerances and end-of-life criteria.

Application

String voltage

Nominal voltage V DC — or click a common value

Unit measured The voltages and resistances you enter refer to this unit.

Rated capacity

Referred to

End-of-life (EOL) criterion According to manufacturer and sizing: ageing factor 1.25 → 80 %; 1.43 → 70 %.

Battery identification (optional)

Manufacturer and model

Installation or internal reference

Measurement date

02 · Capacity test

It is the main criterion for the state of health and for replacement in all the standards. If you do not have one, the diagnosis will rely on indirect indicators.

Discharge test result For VRLA, IEC 60896-21 takes the 3 h discharge (C3) down to 1.70 V/cell, referred to 20 °C or 25 °C, as the reference test.

Actual time to end voltage tA, discharging at the rated current or power for the rate

hmin

Rated time at that rate tS — by default, the one in “Referred to”

hmin

Measured

Rated reference at the same rate

Test ΔSOC % of SOC covered if it was not a full discharge (IEEE 2962 eq. 3)

Actual rate (Xa)

Published rate (Xt) for the time obtained

Unit

Time obtained min

Initial temperature °C, average of the units

Charged at the start?

Full charge: equalizing charge if recommended by the manufacturer and at least 72 h on float before the test (IEEE 450 7.1).

For VRLA, IEC 60896-22 (6.14) only guarantees 90 % of capacity after 24 h of recharge and 98 % after 168 h: test after at least 7 days on float.

Full charge according to the manufacturer before the test.

Hours of charge and float since the last discharge Optional. VRLA: 168 h (IEC 60896-22) · VLA: 72 h (IEEE 450)

For LFP, start with SOC above 97 % and finish below 20 % (IEEE 2962 7.4.1 · 7.7.4).

This is the acceptance test of a new battery

Advanced · temperature correction and previous test

Temperature correction The Best Practices criterion is applied by default. Tables 1 and 2 of IEEE 450 are an advanced option; at low temperature they correct more than Best Practices.

Coefficient α 1/°C, from the manufacturer

Reference

Test end voltage V/cell (informative)

Previous test % of capacity

How long ago years

03 · Internal resistance

Type of ohmic measurement

Reference value commissioning or manufacturer

Unit

Measured values One per unit, or a single value (average or worst). You can paste a column from Excel or from the instrument report.

Two-current DC resistance calculator

R = (V1 − V2) / (I2 − I1), with V1 measured at the end of the current step I1 and V2 at the end of step I2.

V1 (V)

I1 (A)

V2 (V)

I2 (A)

04 · Voltages, temperature and electrolyte

Battery state during measurement

Voltage of each unit V, one per unit. For lithium, cell voltages from the BMS.

Total string voltage V — optional if you have entered the unit voltages

Ambient T. °C

Battery T. °C, average

Maximum temperature difference between units °C — for VRLA, measured at the negative terminal

Electrolyte specific gravity (SG) One per cell or an average. E.g. 1.215

Electrolyte T. °C

Nominal SG

Referred to

Electrolyte level

KOH electrolyte density g/cm³ — requirement 1.19 to 1.23

Insulation to earth of the string

Unit

Connection: reference µΩ

Connection: current max. µΩ

05 · History, BMS and inspection

Age years · required for the life forecast

Design life years

Average operating temperature °C over the year — reduces life above 25 °C

Equivalent cycles

Rated cycle life

SOH reported by the BMS %

Coulombic efficiency %, slow cycle

RTE efficiency % current

Initial RTE %

Visual inspection and events Tick what you have observed.

I have carried out the inspection and there are no anomalies

06 · Indicative diagnosis

No diagnosis yet Choose the technology, complete the data you have (ideally a capacity test) and press Diagnose.

How it diagnoses: the main state of health (SOH) is the capacity one, SOH-C = measured capacity / rated capacity × 100, corrected to the reference temperature: it is the replacement criterion of IEEE 450, IEEE 1188, IEEE 1106 and IEEE 2962. Internal resistance is evaluated with SOH-R = (R_EOL − R_current) / (R_EOL − R_BOL) × 100. In addition, unit voltages, temperature, electrolyte, insulation, connections, age and visual inspection are checked against the tolerances of each chemistry. The verdict is that of the most unfavourable criterion. The remaining life is estimated from the capacity trend, the temperature-corrected design life and the cycle life, taking the most unfavourable: it is an indicative extrapolation. By default the Best Practices criteria are applied: a compilation, prepared by AMPERIS, of the most widely accepted recommendations of international standards and battery manufacturers in the sector.

Notice: merely indicative diagnostic tool, based exclusively on the information provided. It does not replace an exhaustive diagnosis of the battery, which must be entrusted to a qualified engineer from AMPERIS PRODUCTS S.L. or, where applicable, an engineer qualified by the battery manufacturer. Confirm any replacement decision with the manufacturer or with AMPERIS.