tsdos.org

Battery Testing Standards and Best PracticesVolney Naranjo, Senior Applications Engineer

Daniel Carreno, Applications EngineerMegger

tsdos.org

Introduction• Electrical substations require ESS to operate under outage

conditions• Lead Acid and Nickel Cadmium are the main technologies• Regulations and recommended practices to guarantee

safety, reliability and durability• Installation design, installation, maintenance and testing

practices are scattered in different documents• Navigating guide for substation designers and operators

through the documents from NFPA, IEEE, NETA and NERC

tsdos.org

Agenda• Stationary Battery Types• Standards and Regulations• Inspections and Testing• Load Testing• Ohmic Testing

tsdos.org

STATIONARY BATTERY TYPES

tsdos.org

Battery Types: Construction

VLA VRLA Vented NiCd

tsdos.org

Battery Types: ApplicationFeature Long duration General Purpose Short durationPlate characteristic Thick positive plates Moderately thick plates Thin positive platesApplication Telecommunications Switchgear and control

Suitable for UPSUPS

Type of load Constant and low current Constant and switching loads High current loadsMinimum supply time 3 hours 1 to 3 hours 1 hour or lessNominal discharge rate 8 hours 8 hours 15 minutesCycles per year Less than 10 2 to 5 10-20Performance under high discharge/short time rates

Poor Good Good

Performance under low discharge/long time rates

Good Good Poor

tsdos.org

STANDARDS AND REGULATIONS

tsdos.org

Standards and RegulationsStationary Storage

Systems

Safety

NFPA 1 Chapter

52

NFPA 855 Chapters

4 & 9

IEEE C2 Section

14

Design and installation

Sizing of LA

IEEE 485

VLA Installation

IEEE 484

VRLA Installation IEEE 1187

NiCdInstallationIEEE 1106

Maintenance and Testing

VLAIEEE 450

VRLAIEEE 1188

NETA ATS & MTS

NERC PRC-005

Reliability

tsdos.org

Standards and Regulations

tsdos.org

Safety Standards

NFPA 1 Chapter 52NFPA 70 Non-utility –

Articles 90 and 480

NFPA 855 Chapters 4 and 9IEEE C2 Section 14

tsdos.org

Design and Installation Standards

NFPA 855 Chapters 4 and 9IEEE C2 Section 14IEEE 485 Sizing of LA IEEE 484 VLA InstallationIEEE 1187 VRLA InstallationIEEE 1106 NiCd

tsdos.org

Maintenance and Testing

IEEE 1106 NiCdIEEE 450 VLAIEEE 1188 VRLANETA ATS & MTS VLA, VRLA, NiCdNERC PRC-005 VLA, VRLA, NiCd

tsdos.org

Reliability

NERC PRC-005 VLA, VRLA, NiCd

tsdos.org

VLA/VRLA: INSPECTIONS AND TESTING

tsdos.org

VLA/VRLA: Monthly RecommendationsInspection Type Activity

Monthly

VLA VRLAVisual General appearance and cleanliness of the whole installation I N I N

Visual Crack in cells (evidence of electrolyte leakage) I I

Visual Evidence of corrosion at terminals, connectors, racks or cabinets I N I N

Visual Electrolyte levels I N

Visual Verify presence of flame arresters N

Visual Verify existence of suitable eyewash equipment N N

Mechanical Ambient temperature and ventilation I N I N

Mechanical Perform a thermographic survey under load7 N6 N6

Mechanical Structural Integrity of the battery rack N N

Mechanical Verify tightness of accessible bolted electrical connections 5 N6 N6

Electrical Float voltage measured at the battery terminals I I

Electrical Pilot cells (If used) voltage and electrolyte temperature I

Electrical Cell-to-cell and terminal connection resistance N6 N6

Electrical Charger output current and voltage I I

Electrical Unintentional battery grounds I N N

Electrical Battery float charging current or pilot cell specific gravity I

tsdos.org

VLA/VRLA: Quarterly/Tri-annualRecommendations

Add to Monthly

Inspection Type ActivityQuarterly/ Tri-annual*

VLA VRLAVisual Electrolyte levels P

Mechanical Temperature of at least 10% of cells I

Mechanical Temperature of the negative terminal of each cell I

Mechanical Specific Gravity of 10% of the cells of the battery I2

Electrical Float voltage measured at the battery terminals PElectrical Voltage of each cell I IElectrical Cell/unit internal ohmic values I P10

Electrical Charger output current and voltage PElectrical Unintentional battery grounds P P

tsdos.org

VLA/VRLA: Yearly/18-months Recommendations

Add to Quarterly/Tri-annual

Inspection Type ActivityYearly/18-months*

VLA VRLA1

Visual Cell condition I PMechanical Measure negative post temperature NMechanical Specific Gravity of all cells I2

Mechanical Structural Integrity of the battery rack I P PElectrical Float voltage measured at the battery terminals N P N PElectrical Voltage of each cell N NElectrical Cell/unit internal ohmic values N P4 N PElectrical Cell-to-cell and terminal connection resistance I N P3 I N PElectrical AC ripple current and/or voltage imposed on the battery IElectrical Performance or modified performance capacity test of entire bank I8 N8 P4 I9 N9 P10

SettingsVerify Equalizing Voltage Setting is in accordance to Battery's Manufacturer recommendation N N

Settings Verify all charger functions and alarms N N

tsdos.org

NICD: INSPECTIONS AND TESTING

tsdos.org

NiCd: Quarterly/Tri-annual Recommendations

NiCd

Inspection Type

ActivityQuarterly/ Tri-annual*

Visual General appearance and cleanliness of the whole installation IVisual Electrolyte levels I PVisual Crack in cells (evidence of electrolyte leakage) IVisual Evidence of corrosion at terminals, connectors, racks or cabinets IMechanical Ambient temperature and ventilation IElectrical Pilot cells (If used) voltage and electrolyte temperature IElectrical Float current I

ElectricalMeasure battery system voltage from positive-to-ground and negative-to-ground (check for unintentional battery grounds) P

Electrical Float voltage measured at the battery terminals IElectrical Verify Station DC supply voltage PSettings Charger output and voltage ISettings Adequacy of ventilation I7

tsdos.org

NiCd: Semi-annually Recommendations

NiCd

Add to Quarterly/Tri-annual

Inspection Type

Activity Semi-annually

Electrical Voltage of each cell I

tsdos.org

NiCd: Yearly/18-months RecommendationsNiCd

Add to Semi-annually

Inspection Type

ActivityYearly1 / 18

months*Visual General appearance and cleanliness of the whole installation N PVisual Verify existence of suitable eyewash equipment NVisual Verify application of an oxide inhibitor on battery terminal connections NMechanical Ambient temperature and ventilation NMechanical Perform thermographic survey4 N2

Mechanical Intercell connection torque I

Mechanical Verify tightness of accessible bolted electrical connections by calibrated torque-wrench3 N2

Mechanical Structural Integrity of the battery rack I N PElectrical Pilot cells (If used) voltage and electrolyte temperature NElectrical Voltage of each cell N5

Electrical Perform internal ohmic measurements NElectrical Condition and resistance of cable connections I N2 P

Electrical Measure battery system voltage from positive-to-ground and negative-to-ground (check for unintentional battery grounds) N

Electrical Float voltage measured at the battery terminals NElectrical Perform load test N6

Settings Charger output and voltage P

Settings Charger float and equalizing voltage levels. Adjust to manufacturer’s recommended settings N P

Settings Verify all charger functions and alarms N

tsdos.org

NiCd: 6-years Recommendations

NiCd

Add to Yearly

Inspection Type Activity 6 YearsElectrical Performance or modified performance capacity test of entire bank P

tsdos.org

Corrective Actions

• Electrolyte levels should be maintained above the low-level line and up to the full-level line using either distilled or approved-qualitywater.

• Remove any corrosion in posts or terminals.• When inter-cell connection resistance values are not acceptable, even after retorque, connections should be disassembled, cleaned,

reassembled, and retested.• If individual cell temperatures deviate more than 3 ˚C from each other, the problem should be investigated and corrected. For multi-tier

installations, 3 ˚C might not be achievable and the battery manufacturer should be consulted.• Equalizing charge – for applicable battery types, when:

o Individual float voltages deviate from the average value recommended by manufacturero Undercharge condition is suspected and confirmed by lower than expected specific-gravity measurementso Plate sulfationo Immediately if any cell voltage is below the manufacturer’s recommended minimum cell voltage

• Hydration: a battery in this condition should be replaced as soon as possible

IEEE recommends some corrective actions for common issues that can be found duringmaintenance activities.

tsdos.org

LOAD AND OHMIC TESTING

tsdos.org

LOAD TESTING

tsdos.org

Load Testing• Load testing is the only proven

method to determine– Capacity of the battery– True State of Health (SOH)

• Load testing is a time and resource demanding test– Proper understanding of

procedures– Adequate tools

https://www.radiology.ca/article/how-does-exercise-stress-test-work

tsdos.org

Load Testing

tsdos.org

Type of Tests:

Acceptance Test

@ Factory or Upon

Installation

Specific constant discharge

rate & duration

Measures %C, ≥ 90% of

rated Capacity

Capacity may rise after use

Acceptance based on the

Time-Adjusted Method

Baseline for trending

tsdos.org

Type of Tests:

Performance Test

Measures the %C

Constant current or

power

Similar in duration to duty cycle

Test periodically. Every 25%

of Life

For trending:

Prepare the battery

To reflect maintenance

, do not prepare the

battery

https://www.radiology.ca/article/how-does-exercise-stress-test-work

tsdos.org

Type of Tests:

Service Test

Ability to meet a specific

application

Ability to meet the duty cycle

As found, no preparation,

no temperature

correctionAt discretion in between

performance tests

Discharge rate as close as practical

to duty cycle

If fails: review sizing,

maintain & equalize

IEEE485

tsdos.org

Type of Tests:

Modified Performance Test (MPT)

Constant current

modified to include duty

cycle

Tests ability to meet the duty cycle

Measures %C, uses

T correction

Initial conditions

same as Service test

Three types of MPT

described in IEEE450 (Annex I)

Aging factor needed to calculate

minimum test duration

https://www.radiology.ca/article/how-does-exercise-stress-test-work

tsdos.org

Analysis & Replacement Criteria• If at 85% of service life, delivers

100% capacity or greater of the manufacturer’s rated capacity, and has shown no signs of degradation:

– performance testing at two-year intervals instead of 1-year intervals

– Until the battery shows signs of degradation

• Degradation:– Capacity drop>10% from

previous performance test

– Below 90% of the manufacturer’s rating

• Replacement: at 80% Capacity

tsdos.org

OHMIC TESTING

tsdos.org

Test MethodsInternal Ohmic Measurements

─ Ohmic testing can be accomplished using one of three techniques:

– Resistance – Measures only the resistive value of a battery, The battery has capacitive and inductive values as well.

– Conductance – (Actually Admittance) This is the reciprocal of impedance.

– Impedance Testing – Measures the resistive, capacitive and inductive qualities of the battery.

NOTE: Ohmic testing is a relative test NOT an absolute test. We do not test against an absolute value. We test and compare data to a previous test result.

tsdos.org

• Impedance testing has a distinct advantage over resistive type testing. When we look at a schematic representation of a battery there are more than just resistive components to that battery. There are also capacitive and inductive characteristics.

• This means that impedance testing will be able to detect certain problems that resistive measurements can miss; these include negative lug rot as well as negative plate corrosion. These failures will show themselves as changes in inductance and capacitance, not in resistance. In addition many chemical changes in a battery will be seen as impedance changes before they are seen as resistive changes.

Test Methods

tsdos.org

Battery Impedance Test• The following factors will affect the readings (per IEEE 450):

– Cell type and construction– Battery Charge– Electrolyte temperature– Specific Gravity– String length and configuration (Parallel)– Load– Charger (Ripple and other noise) – Make and model of instrument being used– Probe Type– Where the measurement is taken on the battery

tsdos.org

Battery Impedance Test

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Ohm

ic V

alue

(moh

ms)

Cell

Ohmic Results From Two Different Signals

Instrument A Instrument B

tsdos.org

Battery Impedance Test

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Ohm

ic V

alue

(moh

ms)

Cell

Impedance before and after charging

Discharged Charged

tsdos.org

Additional Measurements

• Voltage of each cell• Float Current• Ripple Current• Strap Resistances

tsdos.org

Impedance Data Analysis

Type of Battery Single Test Trending

% change from average (short-

term)

% change from last test (mid-

term)

Overall % change (long-

term)VLA 15 5 30VRLA 10 5 20NiCd 10 5 15

Recommended impedance warning limits

tsdos.org

Impedance Data Analysis

tsdos.org

Summary

Design, Installation,

Maintenance and Testing

Construction

Application

VLA

VRLA

NiCd

tsdos.org

SummaryFire & Life

Safety

NFPA 1

NFPA70

NFPA855

Design & Installation

NFPA 1

NFPA70

NFPA855

IEEE C2

IEEE 485

IEEE 484

IEEE 1187

IEEE 1106

Maintenance & Testing

IEEE 450

IEEE 1188

NETA ATS & MTS

NERC PRC-005

Reliability

NERC PRC-005

tsdos.org

Summary

Fire & Life Safety

NFPA 1

NFPA70

NFPA855

Design & Installation

NFPA 1

NFPA70

NFPA855

IEEE C2

IEEE 485

IEEE 484

IEEE 1187

IEEE 1106

Reliability

NERC PRC-005

Maintenance & Testing

IEEE 450

IEEE 1188

NETA ATS & MTS

NERC PRC-005

Load Testing

Ohmic Testing

tsdos.org

QUESTIONS?