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Battery Monitoring Fundamentals & Experience

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This Presentation Covers…

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BTECH’s History and Experiences

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Why Battery Monitoring is Valuable

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Battery Maintenance & Monitoring Standards

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Examples of Battery Failures

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BTECH’s S5 Battery Monitoring System

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BTECH’s Patented Technology

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Battery Monitoring Introduction

 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

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Battery Monitoring Introduction

 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

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Why Critical System Batteries Should Be Monitored

 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

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Why Critical System Batteries Should Be Monitored

 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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Why Critical System Batteries Should Be Monitored

Early Detection Is The Key To Improving Reliability

% Failures

Theoretical vs Actual Failure Rate 45 40 35 30 25 20 15 10 5 0 1

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4 Years

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Why Critical System Batteries Should Be Monitored

 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 Maintenance Battery checking and assurance occurs only 4 days of the year -- as quarterly battery service is performed

Battery Management Battery assurance occurs 24 X 7

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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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IEEE Std 1491 Recommendations

 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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IEEE Std 1491 Recommendations

 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

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

Float Voltages vs. Unit Number

Float Voltages Show System Is OK

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

Impedance vs. Unit Number Green: Initial Read (Baseline) Red: Maintenance Limit (+20%) Purple: Critical Limit (+30)

The Unit Impedances Show Another Story

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Example #2 – Unit #6

Voltage vs. Time: Voltage Looks OK

Each Yellow Point = One Week

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Example #2 – Unit #6

Impedance vs. Time: Impedance Rises 120% Green: Initial Read (Baseline) Red: Maintenance Limit (+20%) Purple: Critical Limit (+30)

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Example #3 - Unit 13

Voltage vs. Time: Voltage Drops 10%

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

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Example #3 - Unit 13

Impedance vs. Time: 120% in Two Weeks

Failure Within 2 Weeks

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Example #4 – Wet Cell Unit 213

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

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Example #4 - Wet Cell Unit 213

Impedance vs. Time: No Change Recorded

Customer Replaced the Unit

Example #5 - Unit 67

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Impedance vs. Time: Effects of Re-Torquing

Customer Notified

Service Provider Retorques

Battery Finally Replaced

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Example #5 - Unit 67

Voltage vs. Time: Note That Voltages Have Barely Changed

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Example #6 - Unit 42

Voltage vs. Time: Detecting Thermal Runaway

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Example #6 - Unit 42

Temperature vs. Time: Detecting Thermal Runaway

Temperature Sensor Mounted in Cabinet

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Example #6 - Unit 42

System Voltage vs. Time: No Changes

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Example #7 - Unit Impedances

Impedance vs. Unit Number

Notice the 5 Units With High Impedance

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Example #7 - Unit Voltages

Voltage vs. Unit Number During Discharge

These 5 Units Have the Lowest Voltage After Discharge

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Example # 8 – Unit Failing During Discharge Test

Battery Discharge Test Results – JP Morgan 270 Park Ave NYC

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Example # 8 – Unit Failing During Discharge Test

Battery Discharge Test Results – Unit 234 Begins to Collapse

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Example # 8 – Unit Failing During Discharge Test

Battery Discharge Test Results – 9:35 Into Test

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Example # 8 – Unit Failing During Discharge Test

Battery Discharge Test Results – End of Test

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Example # 8 – Unit Failing During Discharge Test

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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Modular System Components TM

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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Integration and Communication

Impedance Delta T

emperature Current

(Float/Discharge )

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S5 System Diagram TM

System Components 

SCM 600 (Controller)  1 per UPS or Inverter System

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

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CT – Current Transducer 1 per String

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VSL – Voltage Sense Lead

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LCL – Load Control Lead

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Typical Applications

 UPS Applications

 Station Battery Systems

 Switchgear

 Emergency Lighting

 Telco’s

 Gensets

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 2 Volt Cells  VLA, VRLA  Monoblocks  4, 6, 8, 12, 16 Volts  NiCad's  1.2 Volts

Battery Types

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S5 VRLA Stack Installation TM

Unmanned Communications: 48V VRLA Stack

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S5 VRLA Cabinet Installation TM

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

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S5 VRLA Station Battery System TM

Switchgear: 10-12 Volt VRLA’s

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S5 Switchgear TM

125 Volt Switchgear: 93 Cell NiCad System

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S5 UPS 2 Volt Wet Cells TM

3-Phase UPS: 480 Volt, 240 Cell System

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S5 UPS 2 Volt VRLA Stack TM

3-Phase UPS: 480 Volt, 240 Cell System

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S5 UPS VRLA TM

3-Phase UPS: 480 Volt, 240 Cell System

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S5 UPS Wet Cell Application TM

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

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S5 Switchgear Application TM

(1) 125 Volt, 60 Cell Systems

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S5 Standard Features and Functions

Measurement of key battery performance parameters for 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

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BTECH BVM Software Interactive Battery Map

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BTECH BVM Software Unit Anomalies

Low Unit Voltage

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BTECH BVM Software Unit Anomalies

Differential Impedances

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S5 Real Time Functionality TM

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BTECH Software TM

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BTECH Software TM

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Integration and Communication

BMS

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Integration and Communication

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Additional S5 System Features TM

 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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What is an Ohmic Measurement

 Ohmic Measurement  Is the terminology used by the IEEE to describe the measurement of a battery cell’s Internal Resistance.  Resistance  Conductance  Impedance

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Why Use Impedance?

 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

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How to Measure Internal Resistance

 Typical Lead Acid Model

63

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How to Measure Internal Resistance

 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.

64

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How to Measure Internal Resistance

 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 65

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Simple Battery Model

 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

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BTECH’s Impedance Method

BTECH Impedance Does Not Discharge Your Batteries

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S5 System Diagram TM

System Components 

SCM 600 (Controller)  1 per UPS or Inverter System

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

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CT – Current Transducer 1 per String

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VSL – Voltage Sense Lead

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LCL – Load Control Lead

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Comparison With Other Methods TM

 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

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Effect of Testing on Batteries

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Impedance vs. Voltage Response

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Comparison With Other Methods TM

 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

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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

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Advanced Battery Management Integration

2.39 2.34 2.305 2.27

Volts Per 2.10 Cell

BTECH Impedance Measurement Window

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Optimized Impedance Test Cycle

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Benefits of Battery Monitoring

 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

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Benefits of Battery Monitoring

 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

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BTECH World Headquarters – Rockaway New Jersey USA

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BTECH Corporate Capabilities

 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

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BTECH Direct Service

Field Service and Support

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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Projects and Customers

 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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Projects and Customers

 Project Spirit (Blackberry Data Center)  Scope: provide battery monitoring systems and technical support  (14) Systems deployed  Status – Project complete, on-line

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BTECH – Strategic Customers