battery monitoring fundamentals &...

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Battery Monitoring Fundamentals & Experience

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BTECH’s History and Experiences

Why Battery Monitoring is Valuable

Battery Maintenance & Monitoring Standards

Examples of Battery Failures

BTECH’s S5 Battery Monitoring System

BTECH’s Patented Technology

This Presentation Covers…

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BTECH developed the first stationary battery monitor based on trend analysis in 1991, based on research begun in the 1980s Leading Indicator: Impedance Rise

Technology has proven itself in the past 15 years First challenge met: proving the method of continuous

battery monitoring Action Plan: Weak cells are identified and replaced

before battery system performance is affected

Battery Monitoring Introduction

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Customers That Embraced Battery Monitoring Have: Eliminated their battery failure risk Ensured performance of their critical power systems Reduced battery maintenance costs

Remote Monitoring Of Hundreds Of Battery Systems Has Demonstrated: Many previously undocumented battery conditions Proof that a need for change is required in the way

critical battery systems are managed Over 4,500 systems installed worldwide

Battery Monitoring Introduction

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Mission Critical Systems Require The Benefits Of On-line Battery Monitoring Systems Real time conditions can be identified and managed,

discharges/thermal runaway / environmental / system failures

Best possible reliability and practices demanded(TIA-942, tier 4)

Systems cannot always be taken of-line for maintenance Extensive annual or periodic tests are expensive and

interrupt business operations Budget constraints often limit or eliminate battery

maintenance Personnel changes

Why Critical System Batteries Should Be Monitored

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Up To 85% Of All Back Up Power System Failures Are Battery Related Monitoring systems can’t detect failures proactively Failures occur between service intervals Inconsistent and often compromised maintenance I.E.E.E recommends measuring the voltage and

impedance values of batteries Lack of customer awareness and/or expertise

Battery Failure Can Happen In 2 Weeks Failure can occur at any time in the battery life cycle Successful discharges or discharge tests can speed failure A quarterly check cannot assure the battery system will

perform


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Early Detection Is The Key To Improving Reliability


Theoretical vs Actual Failure Rate

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1015202530354045

1 2 3 4 5 6 7

Years

% F

ailu

res

Theoretical vs Actual Failure Rate

05

1015202530354045

1 2 3 4 5 6 7

Years

% F

ailu

res

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5+% Of New Batteries Fail Within The Warranty Period Significant impact to critical system reliability Installing new batteries does not reduce risk of failure Users need a method to find the bad ones in time

A warranty is not the same as a performance guarantee

Changes Happening In The Battery Industry China as main supplier of lead and batteries Many new battery types have entered the market

with little or no track record Manufacturers are under pressure to reduce cost The quality of batteries in the market has suffered


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Battery Life Cycle Graph For VRLA Batteries

Impedance Vs. Capacity

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Improve the Way Batteries are Managed

Move From a Fixed Battery Maintenance Schedule to 24x7 Battery Management – 52 PM’s per Year

Instead of 4

Battery MaintenanceBattery checking and

assurance occurs only 4 days of the year -- as

quarterly battery service is performed

Battery ManagementBattery assurance

occurs 24 X 7

® Industry Standards

IEEE Std 450, IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications

IEEE Std 1188, IEEE Recommended Practice for Maintenance, Testing, and Replacement of Valve-

IEEE Std 1491, IEEE Guide for Selection and Use of Battery Monitoring Equipment in Stationary Applications

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IEEE Std 1491 Recommendations

Voltage: Cell, groups of cells, string, and battery terminal voltages.

Current: Individual cell, string, float, charge, and discharge currents are measured and recorded.

Temperature: Cell/battery and ambient temperatures are measured and recorded.

Interconnection resistance checks: Intercell and battery connections are measured and recorded in ohms.

Internal ohmic measurement checks: Each cell/battery is measured for ohmic values.

Specific gravity: Each cell is measured for its specific gravity level.

Electrolyte levels: Each cell is measured for its electrolyte level.

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Discharge run-time analysis: Some monitors may incorporate a run-time prediction during discharge.

Data analysis and reporting : Data is analyzed for trending over time and should be compared with baseline values.. All systems should be capable of immediately reporting serious out-of-tolerance conditions.

Frequency: The measurement intervals are dependent on the individual hardware selected and may be programmable.

AC ripple current: AC components of the string current are measured and recorded. In multistring installations, each string measurement is made and recorded.

Coup de Fouet: Initial voltage drop and recovery of the battery under load.

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Communication interface - Data collected or reported by the battery monitoring device must be integrated. Communication can be as simple as a contact closure or as sophisticated as a fully networked Web-based operation.

Local communications - The monitoring system is usually equipped with a local interface. Local communications will be dependent on site requirements.

Remote communications - Remote communications generally represents communication between the monitoring system and an offsite location. Remote communications will be dependent on site requirements.

Communication protocols and hardware interfaces - Both local and remote communications must occur with a protocol standard over a hardware interface. These may be proprietary standards or a combination of commonly accepted communication standards.


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Examples Of Battery Failures

Found At

Customer Sites

Examples Of Battery Failures

Found At

Customer Sites

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Float Voltages vs. Unit Number

Example #1 - 2 Strings of 40-12V VRLAs

Float Voltages Show System Is OK

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Impedance vs. Unit Number

The Unit Impedances Show Another Story

Example #1 - 2 Strings of 40-12V VRLAs

Green: Initial Read (Baseline)

Red: Maintenance Limit (+20%)

Purple: Critical Limit (+30)

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Voltage vs. Time: Voltage Looks OK

Each Yellow Point = One Week

Example #2 – Unit #6

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Impedance vs. Time: Impedance Rises 120%

Green: Initial Read (Baseline)

Red: Maintenance Limit (+20%)

Purple: Critical Limit (+30)

Example #2 – Unit #6

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Voltage vs. Time: Voltage Drops 10%

Unit 50 Impedance: 5.06 Milli-ohms (180.07% of String Initial Measurement) [2.81 Milli-ohms]

Example #3 - Unit 13

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Impedance vs. Time: 120% in Two Weeks

Failure Within 2 Weeks


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Voltage vs. Time: 10% Voltage Drop within 2 Weeks

Example #4 – Wet Cell Unit 213

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Impedance vs. Time: No Change Recorded

Customer Replaced the Unit

Example #4 - Wet Cell Unit 213

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Impedance vs. Time: Effects of Re-Torquing


Customer Notified

Service Provider

Retorques

Battery Finally

Replaced

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Voltage vs. Time: Note That Voltages Have Barely Changed


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Voltage vs. Time: Detecting Thermal Runaway


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Temperature vs. Time: Detecting Thermal Runaway


Temperature Sensor Mounted in Cabinet

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System Voltage vs. Time: No Changes


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Impedance vs. Unit Number

Example #7 - Unit Impedances

Notice the 5 Units With High Impedance

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Voltage vs. Unit Number During Discharge

Example #7 - Unit Voltages

These 5 Units Have the Lowest Voltage After Discharge

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Battery Discharge Test Results – JP Morgan 270 Park Ave NYC

Example # 8 – Unit Failing During Discharge Test

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Battery Discharge Test Results – Unit 234 Begins to Collapse


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Battery Discharge Test Results – 9:35 Into Test


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Battery Discharge Test Results – End of Test


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Battery Discharge Test Results – Unit 234 Discharge Details


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The Product

BTECH’s Fifth Generation Battery Monitoring System

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SCM-600 Control Module

Voltage VM24i Module VM24i with CT

Real Time Monitoring• Cell Impedance • Ambient & Pilot Temperature

• String & System Current (Float/Charge/Discharge)• Cell & System Voltage (Float/Discharge)

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Modular System Components

® Integration and Communication

Impedance emperature

Delta T Current (Float/Discharge )

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S5 System Diagram

System Components SCM 600 (Controller)

1 per UPS or Inverter System

VM-24Up to 24 VSLs and 4 Ts per unit

CT – Current Transducer 1 per String

VSL – Voltage Sense Lead

LCL – Load Control Lead

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® Typical Applications

UPS Applications

Switchgear

Telco’s

Station Battery Systems

Emergency Lighting

Gensets

® Battery Types

2 Volt Cells

VLA, VRLAMonoblocks

4, 6, 8, 12, 16 Volts NiCad's 1.2 Volts

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Unmanned Communications: 48V VRLA Stack

S5 VRLA Stack InstallationTM

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3-Phase UPS: 40-12v (480V) VRLAs

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S5 VRLA Cabinet Installation

® S5 VRLA Station Battery System

Switchgear: 10-12 Volt VRLA’s

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125 Volt Switchgear: 93 Cell NiCad System

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S5 Switchgear

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3-Phase UPS: 480 Volt, 240 Cell System

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S5 UPS 2 Volt Wet Cells

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S5 UPS 2 Volt VRLA Stack

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S5 UPS VRLA

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(3) 3-Phase UPS: 480 Volt, 240 Cell Systems

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S5 UPS Wet Cell Application

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(1) 125 Volt, 60 Cell Systems

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S5 Switchgear Application

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Measurement of key battery performance parametersfor trend analysis (failure prediction & prevention)

Unit Impedance - Impedance is the leading indicator of battery failure and finds bad batteries Plate cracking, warping, corrosion, post & strap

corrosion and cell dry-out are easily detectible Interconnect problems Initial measurements for each unit used for baselines

Unit Voltage – Can also be a leading indicator of failure Dendritic shorts Thermal runaway

Ambient & Pilot Cell Temperatures – Problem prevention Environmental conditions

S5 Standard Features and Functions

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Interactive Battery Map

BTECH BVM Software

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Unit Anomalies

BTECH BVM Software

Low Unit Voltage

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Unit Anomalies

BTECH BVM Software

Differential Impedances

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S5 Real Time Functionality

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BTECH Software

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BMS

Integration and Communication

® Integration and Communication

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Additional S5 System Features

Complete Isolation from the Battery String System is not powered by your batteries Completely invisible and passive to the battery system,

UPS/rectifier and load Factory Designed and Built Wiring Harnesses

Ensure system reliability Simple installation in 50% less time Designed to meet site requirements

BTECH’s Unique Safety Fuse System Allows easy battery replacement Reduces battery replacement costs by up to 50%

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Ohmic Measurement Is the terminology used by the IEEE to

describe the measurement of a battery

cell’s Internal Resistance.

Resistance Conductance Impedance

What is an Ohmic Measurement

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BTECH utilizes an impedance measurement method to determine the ohmic value.

Why? Impedance is the only methodology that

captures all modes of cell failure Corrosion Dry out Sulfation Optimized impedance test signal Scaled to the battery type

Why Use Impedance?

® How to Measure Internal Resistance

Typical Lead Acid Model

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Rs Series resistance (metallic), posts, straps, plate to strap, and intercell welds. Acts as a simple resistor so does not change with frequency.

Rct - Charge transfer resistance (electrochemical) Cdl - Double layer capacitance (electrochemical),

charge separation near the surface of the electrodes from ions close to the plate surface.

Zw - Warburg (Diffusional) impedance (electrochemical), non linear diffusion of ions in the electrolyte.

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Internal ohmic testing is based on measuring the response of the cell to a voltage or current stimulus, and relating the response to an ohmic value. The values of the components of the model (Rs, Cdl,

and Rct) correlate to the ohmic value calculated by the instrument.

A high frequency test signal will tend toward Rs The Metallic Resistor

A low frequency test signal will tend towards Rs + Rct + Zw The entire battery

At high frequency Z ≈ Rs At low frequency Z ≈ Rs + Rct + Zw Tests at no frequency tend toward RS

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A DC resistance test only measures Rs and

Rct and ignores Zw and Cdl

Impedance testing uses an AC signal to

include the capacitor in the measurement

BTECH 215 Ω, Voltage, Current

Simple Battery Model

® BTECH’s Impedance Method

BTECH Impedance Does Not Discharge Your Batteries

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S5 System Diagram

System Components SCM 600 (Controller)

1 per UPS or Inverter System

VM-24Up to 24 VSLs and 4 Ts per unit

CT – Current Transducer 1 per String

VSL – Voltage Sense Lead

LCL – Load Control Lead

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Impedance vs. Resistance (i.e. “Voltage Response”) Voltage response results on battery systems on-line are

affected by the charger, line noise and battery type 1 cycle measurement window Requires repeated deep DC discharges to get results Measurements are not repeatable

Modular Monitoring Systems Small modules located on and powered by the batteries at all

times Wireless or fiber optic communications buss Measurements remain dormant until called upon by PC based

master Weak load signal (1A) provides poor signal to noise ratio Technology is limited to a few battery types

Comparison With Other Methods

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Impedance vs. Voltage Response

Effect of Testing on Batteries

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Systems Using AC Ripple Or Line Voltage Measurement signal is always changing due to ripple,

noise and load, leading to inconsistent results Impossible to separate ripple effects from data Cannot establish baselines for trending

Additional Comparisons BTECH Systems install in half the time with less wiring BTECH integrates with any battery type Integrates with any building management system Easily integrates with network operations Easy to operate point and click software Does not require a computer in the UPS room, each

BTECH unit functions as it own master

Comparison With Other Methods

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2.39

2.10

2.27 2.305

2.34

VoltsPerCell

Advanced Battery Management Integration

BTECH Impedance Measurement Window

® Optimized Impedance Test Cycle

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Critical system battery performance is assured Detection of major battery problems with enough time

to respond Reliability of backup power is increased Risk and revenue lost due to downtime are virtually

eliminated

Battery management and maintenance costs can be reduced significantly Customer experience: Battery service life can be

increased up to 100% when weak cells are replaced in time

Reduction of manual maintenance

Benefits of Battery Monitoring

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System up time is increased Maintenance windows are shortened Batteries can be replaced proactively

Site acceptance testing is improved Battery data is captured with the BTECH System Additional equipment does not have to be rented Defective cells can be replaced before the

UPS/Battery system is put on line Overall Battery management is improved

Better overall evaluation and management of the total Battery Asset with Real time and Trended data

Improve continuity of service and system performance Better compliance with Industry and Local standards

Benefits of Battery Monitoring

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BTECH World Headquarters – Rockaway New Jersey USA

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Wosub, HUB Zone Certification Complete Services:

Complete Documentation and Submittals Turn key project Management Engineering and Design Installation Services Commissioning, Start-up and Training

Remote Monitoring and Maintenance Contracts Technical Help Desk Support World Wide Service Network

BTECH Corporate Capabilities

® Field Service and Support

BTECH Direct Service

Factory Authorized Partners

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Projects and Customers

Scope: Provide all monitoring hardware for

ongoing system expansion and

developments

Maintenance and Monitoring service

provided for 19 centers, 228 systems

Status –On-line/ in process

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Project Dolphin (Apple Data Center) Scope: provide Battery monitoring systems

and technical support (48) 240 Cell systems Largest Commercial Data Center in North

America

Status - in process


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Project Spirit (Blackberry Data Center)

Scope: provide battery monitoring systems and technical support (14) Systems deployed Status – Project complete, on-line


® BTECH – Strategic Customers

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