Done By: Ayman Ahmed - O&M Dep.

IntroductionIntroduction

Batteries and generators are normally the last chain in the network to keep up power during an AC mains frailer. Due to its importance and due to the design of nowadays battery, regularly battery testing is needed to control the battery's State of Health.

Background:Background:

There are many ways to test a battery , just as there are many reasons to test a battery.

The passive battery testing techniques available today are generically referred to as Ohmic test, Conductance Test.

Ohmic Testing Technology:Ohmic Testing Technology:

In Simplest technical terms, Ohmic technology is based on Ohms Low , which expresses the relationship between volt, amperes and ohms in an electrical circuit.

V = I R

(V) : Voltage , (I) Current , (R) : Resistance

Thus, Omic technology attempts to use voltage and current to determine the resistive characteristic of a battery. Higher resistance equates to reduced ability to produce current. This characteristic is translated into a measurement of resistance or impedance (Ohms) in some Ohmic technologies.

Conductance technology:Conductance technology:

Definition: Conductance describes the ability of a battery to conduct current. It is the real part of the complex admittance and is measured in the Systems International (SI) unit of “Mhos”, or the International unit of “Siemens”.

The conductance test is performed by applying a low frequency AC voltage signal of known frequency and amplitude across a battery and observing the AC current that flows in response to it. The AC conductance is the ratio of the AC voltage, to the amplitude of the AC voltage producing it. Various test data have shown that at low frequencies, the conductance of a battery is an indicator of battery state-of-health showing a linear correlation to a battery’s timed-discharge capacity test result. This can used as a reliable predictor of battery end-of-life.

V

t

A

T/2

V: Voltage, t: Time, A: Amplitude, F:Frequency

80

70

60

50

40

30

10

20

500 700 900 1100 1300 1500

Conductance (Siemens)

Dis

char

ge

(Min

uet

s)

F = 1/TF = 1/T

Conductance Testing Technology Conductance Testing Technology Benefits: Benefits:

Conductance measurements are faster and easier than active test measurement.

Conductance testing of stationary batteries in the mobile telecom environment has been shown to be an effective method of determining the relative

battery condition and performance potential.

Conductance testing is a safe method, passive test, no discharge.

Digital MidtronDigital MidtronDigital MidtronDigital Midtron

6V/12V Battery Conductance 6V/12V Battery Conductance TesterTester

6V/12V Battery Conductance 6V/12V Battery Conductance TesterTester

C065 DuraProbe Interface

Fuse

Digital Midtron Conductance battery Tester

Spare Parts

6V-12V Selection On/Off Review

9V Allkaline Battery

Specifications:Specifications:

Model number DM-3200

Designed to take conductance measurements exclusively on 6 and 12 volt Lead/Acid batteries while either on line (float service) or off line.

Applications: Test 6v and 12v batteries (low and high voltage errors for batteries measuring out of range) Test circuitry matching the Midtronics Micro Celltron.

Operating Range: Voltage : for 12 v batteries: 11.5 - 15v, for 6v batteries: 5.5v to 7.7v, Amp Hour: approximately 5Ah to 600 Ah, Conductance: 100 – 3200 Siemens.

Test Data Storage: Last test result (single test only) retained for review after test set powers down. Each subsequent test overwrites the prior test result.

Test Result: Dc voltage and conductance expressed in “Siemens”.

Jars/Straps: Test result for an individual 6 volt or 12 volt jar test only.

Accuracy: +/- 2% across test range.

Reverse Polarity Protection: Diode protected.

Power Requirements: Unit is powered by the battery under test; one replaceable 9V alkaline battery used to power the display.

Test Cables: Interchangeable interface (one standard # C065 DuraProbe cable set and spare probe tips provided with each tester).

Voltmeter resolution: +/- 20 mV DC

Calibration: Auto calibration prior to every test, no future calibration required.

Visual Output: STN LCD- 2line 16 character, extended temperature.

Operating Temperature Range: 0º C to + 40º C,95% relative humidity, non-condensing.

storage Temperature Range: -29º C to + 70 º C, 95% relative humidity non-condensing.

Over voltage protection: Fused protected to 60 VDC, four spare fuses included.

Specifications :Specifications :

Battery Testing And Operation:Battery Testing And Operation:

Automatic Battery Testing: The Digital Midtron Analyzer is ready to test VRLA (Valve Regulated Lead Acid) batteries with the DuraProbe cable automatically without requiring to setup or calibration. The set automatically begin to measure upon the establishment of a good contact between the Analyzer probes and the battery posts. All Macro sites that we have in Vodafone network were equipped with originally installed VLRA batteries with two types (Tudor, Oerlikon).

Tudor Battery

Oerlikon Battery

Procedure of on -line testing: Procedure of on -line testing:

Fig. (1), Bad contactFig. (2), Good contact

Disconnect the power of the site for period you will test during it.

The analyzer must have a good contact with both the positive and negative battery posts, as shown in fig.(1,2) .

The analyzer will automatically begin to be in its measuring modes (Self Calibration, Auto Ranging, Testing, Result in volts and siemens.

Repeat the previous steps for each battery wanted to be tested, and do not forget to reconnect the power to the site.

The test result will display on the LCD of the analyzer and disappear when the probes are disconnected from the battery posts. To show again the last result, just press the On/Off Review key.

Procedure of on -line testing: Procedure of on -line testing:

Each test takes less than 10 seconds, and the test result held in memory until the next test is completed. Each subsequent test

overwrite the previous test result.

Sound Beeps & Error Messages:Sound Beeps & Error Messages:

I. If the battery being tested has a voltage under the appropriate specified limit (6.3V or 12.6V), the test set will sound a dual audible beep after completing the test indicating a low test voltage. If the battery being tested has a voltage below (5.5V or 11.5V) as appropriate, a “low voltage” message will be displayed and the unit will not test. This indicates that the subject battery’s state of charge is too low to be tested or has some other internal fault condition,which will prohibit a valid test result.

II. If the battery being tested has a voltage over (7V or 15V) as a appropriate “high voltage” message will be displayed and the unit will not test. This indicates that the subject battery’s state of charge is very high to be tested.

III. If the Analyzer has not good contact with the positive and negative battery posts a “Check Connection” message will be displayed and the unit will not test.

References value:References value:

We have two types of VRLA (6V) batteries (Tudor, Oerlikon) which installed inside the Macro sites.

We have a conductance reference value for each type of previous maintained batteries as shown below, the conductance result which we will obtain from battery conductance tester should be compared with a certain conductance value and test conditions (Temperature, VRLA Batteries) should be considered.

Tudor: 3000s

Orlikon: 3200sResult = Reference /

1.035At 21°C

Conductance

Status Of Tested Battery:Status Of Tested Battery:

If the conductance result approaches or above the conductance reference value, it means that the tested battery is very good state.

If the conductance result is around 70% of the conductance reference value, it means that the tested battery is not good by the way any battery that is 30% or below the string/ system average should be considered questionable .

If the conductance result is under 60% of the conductance reference value, it means that the tested battery is bad and it must be out from the network.

Digital Midtron Practical Test:Digital Midtron Practical Test:

Site 15: There was power problem in site 15 that the site goes to be down after 30 minute frompower cut time and the installed batteries did not carry the site more than this period, so I did a conductance test on the site’s batteries by the Digital Midtron DM-3200 battery tester and I found that there were 6 bad batteries have a

conductance value of 63% from the reference value and 3 bad batteries under 60% from the reference value.

Successful battery conductance test in sites 124, 404, 186,480,421,254,436

Ayman Ahmed Abdel Halim, Junior NFM EngineerAyman Ahmed Abdel Halim, Junior NFM Engineer

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