Conductance Measurement as an Aid to Determining Replacement Strategy

- Its application worldwide -

Youngdae Jun

Korea Thermo-Tech Co.,Ltd. Korea

March 30, 2004

Lead-Acid Battery Chemical Reaction

H2SO4

H2O

Sulfuric Acid & Water - Electrolyte

ANODE

PbO2

LEADDIOXIDE

+

CATHODE

Pb

LEAD

-

H2O

ANODE

PbSO4

LEADSULPHATE

+

CATHODE

PbSO4

LEADSULPHATE

-

PbO2 + Pb + 2H2SO4 2PbSO4 + 2H2OCHARGE

DISCHARGE

Battery Routine Inspection

• 1. Visual Inspection

• 2. State of Charge (SOC)– Open Circuit Voltage (OCV)– Specific Gravity (S.G.)

• 3. State of Health (SOH) Percentage of Capacity

Over 90% - ExcellentOver 80% - GoodBelow 80% - No Good

Degradation is indicated when the battery capacity dropsmore than 10% from its capacity on the previousperformance tests, or is below 90% of the manufacturerspublished ratings. (p.6)

A capacity below 80% shows that the battery rate ofdeterioration is increasing even if there is ample capacity tomeet the load requirements. (p.9)

IEEE Standard 1188-1996

Battery Capacity TestingAutomotive Standby Motive Power

Function

Short period of time, big current to start engine

Long period of time, stable current when power is out

Long period of time, stable current for driving forklift, etc.

Rating-18℃ Cold Cranking Ampere

e.g. ： 500CCA

Ampere-Hours (Ah)

e.g.: 200Ah, 10h rate

Ampere-hours (Ah)

e.g.: 100Ah, 10h rate

Testing

½ CCA Discharge Test:

Room temp. 250A load 、

Discharge 15s 、 see V drop

Time Discharge Test ：

Room temp. 20A load 、

Discharge 10h 、 see V drop

Time Discharge Test:

Room temp. 10A load

Discharge 10h 、 see V drop

Decision12V Battery ＜ 9.6V

No Good

2V Cell ＜ 1.75V

No Good

Capacity ＜ 80% N.G.

2V Cell ＜ 1.75V

No Good

Capacity ＜ 80% N.G.

Conductance Measurements • It is a measure of the plate surface which

determines how much chemical reaction or power the battery can generate.

• The battery state of health can be diagnosed by the change of the plate surface.

Conductance and Discharge Test

e.g. A bottle has 500 ml of water ， how do you know if the bottle has less than 400 ml of water （ 80% ）？

a) by cup measure

b) by weight

c) By water level

Conductance measurement is like weight or water level measurement to monitor the loss of water and calculate the remaining volume of water (capacity).

Conductance measurements can be performed by applying a voltage of known frequency and amplitude across a cell / unit and observing the AC current that flows in response to it. The conductance is the ratio of the AC current componentthat is in-phase with the AC voltage, to the amplitude of theac voltage producing it. (p.15)

Significant changes in the value typically indicate a significantchange in the cell, which may be reflected in its performance.(p.15). Changes in ohmic values in excess of 20% should be considered significant.(p.15)

How Conductance Test Is Performed (IEEE Standard 1188-1996)

Conductance Test

1. A low voltage A/C Signal is Impressed across the battery terminals (VAC)

2. 2. The A/C Current (IAC) Response is measured

3. 3. Conductance (G) is calculated using Ohm’s Law: G = IAC/VAC

Plate Surface Area

Linear Relationship %

Rate

d C

apaci

ty%

Ori

gin

al V

alu

e

% Rated Capacity

100

95

90

85

80

130

120

110

100

90

80

% Life10 20 30 40 50 60 70 80 90 100

Conductance

Source: Johnson Controls Form 41-7271 Rev. 8/94

Conductance Correlation with Battery Capacity

Application in Auto IndustryN.

AmericaEurope Japan Others

GM

MCR-410

Opel

MCR-411

Fiat

MCR-360

Toyota

MCR-440

SGM

MCR-430AP

FORD

MCR-490/390

BMW

MCR-560

Renault

MCR-330

Nissan

MCR-620

Hyundai

MCR-570

Chrysler

MCR-420

Mercedes

MCR-717

Audi/VW

MCR-340

Mitsubishi

MCR-530

Proton

MCR-500AP

Volvo

MCR-320

Land Rover

MCR-393Mazda

MCR-491

Saab

MCR-311

Jaguar

MCR-394

Honda

MCR-540

Application in Battery Industry

Exide Yuasa Napa

MCR-350 MCR-417 PSM-2

GNB Furukawa Interstate

CPS-3000 MCR-430AP MCR-500LBSA

ACDelco Varta Shanghai

MCR-400 MCR-400 Delphi

MCR-450 MCR-460AP

Wal-Mart Century Yuasa

MCR-500 MCR-400

Application in Standby Industry Power / Utility Wireless & Broadband Telecom Railroad/Transportation

Ameren, Inc. AirTouch Paging Ameritech Burlington Northern-Santa Fe RailBritish Columbia Hydro Ameritech Cellular AT & T Gateway Western Railway Carolina Power and Light Bell South Mobility Bell Atlantic National Air Traffic Services (UK)ComEd Bell South Wireless Data Bell Canada O'Hare International AirportConneticut Yankee Nuclear Pow. Cellular One Bell South Union Pacific Railroad Consumers Power Company Clearnet British Telecommunications UPS and CO End UsersEdmonton Power Cox Communications China Telecom Amoco PetroleumEntergy Operations, Inc. Digiph PCS GTE City Of Los AngelesGPU Nuclear Corporation GTE Mobile Comm. MCI WorldCom Exide ElectronicsHouston Lighting & Power Co. Media One New England Telephone Co. Lockheed Technical Operations Illinois Power Company Metropolitan Fiber Systems Maritime Tel. & Tel. Co. Royal Canadian Mounted PoliceNew York Power Authority Perfect Wireless Pacific Bell Walt Disney World Co.Niagra Mohawk Power Rogers Cantel Pacific Telecom, Inc. Power and Network OEMSOntario Power Generation Southern Maryland Cable, Inc. Phillipines Long Distance C & D Charter Systems Siemens Stromberg-Carlson Sprint PCS PTI / Century Telecom. East Penn BatterySouthern California Edison Telus Mobility Quest Communications Exide CorporationUnion Electric Time Warner Comm. SBC FIAMM TechnologiesWisconsin Electric Vodaphone - PrimeCo Southwestern Bell Lucent Technologies

Sprint Marconi CommunicationsU.S. West Northern Battery

Teligent Communications

Internal Ohmic Measurements

Impedance measurements can be performed by passing a current of known frequency and amplitude through the battery and measuring the resultant ac voltage drop across each cell/unit.

Conductance measurement can be performed by applying a voltage of known frequency and amplitude across a cell/unit and observing the ac current that flows in response to it.

Resistance measurements can be performed by applying a load across the cell/unit and measuring the step change in voltage and current.

Impedance and resistance are inversely related to conductance.

Among the three ohmic testing methods, why customers choose Midtronics conductance tester

not impedance or resistance

On-line Test Data: Reliable and Repeatable

Easy of Use and Reasonable Price

Company Reputation and After-sales Service

New Technology & Product Research & Development

Electric Power Research Institute (USA)

“Battery Performance Monitoring by Internal Ohmic Measurement”

Testing performed as part of this project indicates that a linear relationship appears to exist most often between conductance and capacity. The practical implication of this observation is that an inverse relationship should exist between impedance or resistance and capacity. (2-19)

EPRI TR-108826, December 1997

British Telecom Paper at Intelec 1998

“Impedance/Conductance Measurements as an Aid to Determining Replacement Strategy”

Conclusions:

This paper has shown that two particular parameters, namely conductance/impedance monitoring and temperature/time/life factors can be effective in forecasting battery replacement timescales.

(In 1999 British Telecom (BT) purchased 500 units of Midtronics Micro Celltron tester to equip its technicians. By the end of 2001, BT had purchased 700 units of Midtronics Micro Celltron tester.)

France Telecom Paper at Intelec 2001“Measurement of Impedance and Conductance: Myth

and Reality Tested in the Field”

Analysis and Conclusion

In a power system architecture serving telecommunications equipment, batteries are used in an emergency through lack of normal electrical supply, generally the mains. It is therefore absolutely impossible to disconnect them to test their residual capacity by measurement of conductance or impedance. These must be carried out online. Consequently, as soon as a battery is made up of more than one string, it is necessary to take into account the correction factor.

(p. 419, Analysis and Conclusion)

France Telecom Paper at Intelec 2001“Measurement of Impedance and Conductance: Myth

and Reality Tested in the Field”(continue from previous page)

For test apparatus A, measuring conductance, measurement and the correction factor are reliable. It applies power to the terminals of the tested monobloc and measures the current. These two parameters are therefore mastered.

For test apparatus B, measuring impedance, it is not adapted to multi-string batteries in a traditional telecom context. It applies a current that is divided into all the strings of the battery. The current then developed at the terminals of the tested monobloc is usually too weak to be correctly measured by the tester (Table 6).

(p. 419, Analysis and Conclusion)

France Telecom Paper at Intelec 2001“Measurement of Impedance and Conductance: Myth

and Reality Tested in the Field”(continue from previous page)

Regarding the conductance measured with apparatus A, the fault thresholds determined from measurements on more than 1200 monoblocs (AGM 12 V 75 Ah) are as follows:

Loss of conductance less than 30%

= loss of capacity less than 20%

Loss of conductance more than 40%

= loss of capacity more than 20%

(p. 420, Measurement Results)

Time Warner Telecom (USA)

“Letter of Product Recommendation” Feb. 29, 2000

A simple, fast, economical, and relatively accurate tool is required as a result of the increasing need for the testing and maintenance of the batteries being utilized in our network.

Several battery testers have been tested in our lab and in the field. In terms of accuracy, cost, ease of operation, safety and reputation for good product support, we have determined that Midtronics Micro Celltron Conductance Tester is the recommended battery tester for TWTC.

NEXTELL (USA)

“DC Power and Battery Plant Optimization and Periodic Battery Plant Preventive Maintenance Procedure” Rev. 1.1 April 10, 2001

8.0 Estimating Battery Runtime – Load/Conductance Testing

The ability of the battery plant to support the load should be performed annually after all other maintenance procedures have been completed.

The runtime available from a battery plant can be determined in two ways. One method is to simply shut down the rectifier and let the site run on battery power. While this is easy, it runs the risk of dropping the site if the batteries are defective. Conductance testing produces more accurate results, and has no risk of dropping the load from the plant.

Bell Atlantic (USA)

“Product Selection Notice – Midtronics Micro Celltron Battery Conductance Tester”

Transport Technology Planning GroupDocument Number 1999-00204-OSP, April 15, 1999

The purpose of this Product Selection Notice is to inform the field of the selection of the Midtronics Micro Celltron Conductance Battery Tester for use in Bell Atlantic. The Micro Celltron is used for maintenance testing of valve regulated batteries in the outside plant, at customer locations or in other applications where valve regulated batteries are used. The Micro Celltron Tester provides a quick and accurate way to identify battery deficiencies by imposing a small signal during test and measuring the resulting AC current against a reference value. The test causes little change o the dynamics of the battery and can therefore be repeated as desired. The Micro Celltron Tester replaces the Midtronics Celltron Plus Tester for new purchases for in-service measurements of the condition of valve regulated batteries.

Verizon (USA)

“Battery Conductance Testing M&P” (method and procedure release)

April 23, 2002

This M&P is emphasizing the importance of battery conductance testing at remote terminal sites and customer premise locations equipped with battery backup. The Midtronics’ Micro Celltron conductance Meter is the test set of choice for battery testing because it is non-intrusive, intuitive, accurate, and quick compared to other forms of battery testing. Consequently, these test results will provide reliable battery health data, which will enable Verizon to manage its annual budget forecast more efficiently.

“Battery Vendor will charge the battery for a period of 72 hours before shipping to site, and prior to shipment, will test each battery with a Micro Celltron Conductance test set. Additionally, the vendor will place a label on the battery with the following information: conductance reading, PO#, battery type, related volt reading and amp hour capacity.”

Micro Celltron CTM-300 Kit

• CTM-300 Complete Kit includes:CTM-300 Complete Kit includes:

• CTM-100 Micro CelltronCTM-100 Micro Celltron

• Protective Carry CaseProtective Carry Case

• IR PrinterIR Printer

• Two Test CablesTwo Test Cables

• Spare BatteriesSpare Batteries

• Spare FusesSpare Fuses

Celltron Ultra BSU-6000 Kit• BSUBSU-6000 Complete Kit includes:-6000 Complete Kit includes:

• BSU-600 Celltron UltraBSU-600 Celltron Ultra

• Protective Carry CaseProtective Carry Case

• Two Test Cables (Clamp & Probe)Two Test Cables (Clamp & Probe)

• Spare Batteries & Spare FusesSpare Batteries & Spare Fuses

• IR PrinterIR Printer

• Temp SensorTemp Sensor

80% Capacity versus % Conductance

Battery Industry ： Capacity ＜ 80% Replace

Midtronics ： Conductance ＜ 70%Warning

＜ 60% Replace

B.T. ： Conductance ＜ 65% Warning

＜ 55% Replace

France Telecom ： Conductance ＞ 70% = Capacity ＞ 80%

Conductance ＜ 60% = Capacity ＜ 80%

Guidelines on Measurement

a) - The battery tested should be under stable conditions (Not in the process of charging and discharging) ；

b) - The battery should be tested under the same condition. (We compare apple with apple, not apple with orange);

c) - The test probes should be placed as close as possible to the battery posters (to avoid the impact from other metal accessories)

d) - The test can identify good or bad cells

What is New?

•New Technology: DFIS (Discrete-Frequency Immittance Spectroscopy)

•New Products: onGUARD & inGEN

Thank You!Are there any questions?

www.batterytestsystem.com

Contact: kthermo@batterytestsystem.com