1. Battery Monitoring
Why – What - How
DIEBOLD
POWER SOLUTIONS LLC

2. Agenda Introduction Why should I monitor?
Increase Battery System Reliability
Cost savings
Safety
What technology should be used
A “battery monitor” is not enough
Resistance vs. Impedance, why does it matter
Electrical Engineer version
Pipe Analogy
How does ripple noise affect my measurements
Case study
Product description
Configuration examples

3. Based in Boca Raton Florida
Who is Alber?
Established 1972
Based in Boca Raton Florida
We manufacture battery test equipment based on extensive experience in and knowledge about Battery design and Battery aging characteristics. We are the Battery Test Experts!

4. Battery Monitors, Test Equipment and Educational Services
Condition assessment
Capacity assessment
Education
On-line
Public
Manual
Cellcorder
Single Cell Tester
SCT-200
Battery Basic Seminar
Digital Hydrometer
DMA-35n
Automatic/Continuous
Monitor system
BDS and MPM
Battcon Conference
Test Tools
RM-650 & PSC-10
Off-line
In-house
Contact Resistance
Micro-ohm meters
BCT-2000
Battery Cell Scanner
Battery Basic Seminar
MLT-12
Momentary Load Tester
CLU
Continuous Load Units
Product training

5. Capacity vs. Condition assessment. What’s the difference?
Battery Capacity Testing. Off-line discharge test using load bank with constant current capability (ability to adjust resistance as voltage drops) while continuously monitoring each individual battery cell voltage to identify the bad cells.
Time consuming (1 to 10 hours plus re-charge time)
Requires external load bank and sometimes backup battery
Reliable. Only way to truly assess the battery’s absolute capacity

6. Capacity vs. Condition assessment. What’s the difference?
Condition assessment. On-line test measuring the internal resistance of each battery cell. As a battery condition declines, the resistance increases. Increased internal resistance indicates aging or pre-mature failure before the cell cause critical failure to the battery
On-line, non-invasive test that can be performed manually (Cellcorder) or automatically (Monitor System)
Provides absolute state-of-health assessment parameters on individual cell level
Detects failing cells before they cause problems
Does not provide an absolute capacity value and chemical problems are more difficult to detect in an early stage.

7. Why? Why Monitor? Batteries International July 2003
“-Batteries are the heart and Achilles heel of critical infrastructure and have been so for the last 20 Years” EYP CTO/CEO Peter Gross.

8. Why Monitor?
Why?
US Department of Energy estimates that total annual losses from Power outages for large industries may be as high as 150 billion dollars.

9. Why? Why monitor? Increase battery system reliability Cost savings
Avoiding costly unplanned down time
Reliable test data through consistent data acquisition
Cost savings
Reduced maintenance man-hours or redirection of maintenance crew to proactive maintenance activities
Optimizing battery life
Safety
Limiting personal hands-on and avoiding human errors
Avoiding catastrophic battery failures

10. Why? Why monitor? Increase battery system reliability
Avoiding costly unplanned down time
Reliable test data through consistent data acquisition

11. Avoiding costly down time
Why?
Uptime (9’s) Downtime / year
99.9% (3) 8 hr, 45 min, 36 sec
99.99% (4) 52 min, 33.6 sec
99.999% (5) 5 min, sec
% (6) sec
% (7) sec
Source: 7X24 Exchange 2003 Spring Conference

12. Avoiding costly down time
Why?
Can you afford not to monitor?
Industry Avg. Cost Per Hour*
Cellular communication $41,000
Telephone Ticket Sales $72,000
Airline Reservation $90,000
Credit Card Operation $2,580,000
Brokerage Operation $6,480,000
* Does not include intangible losses such as damaged reputation and lost customers.

13. How much would a power outage cost your company?
Avoiding costly down time
Why?
Can you afford not to monitor?
Industry Avg. Cost Per Hour*
Cellular communication $41,000
Telephone Ticket Sales $72,000
Airline Reservation $90,000
Credit Card Operation $2,580,000
Brokerage Operation $6,480,000
How much would a power outage cost your company?
Source: 7X24 Exchange 2003 Spring Conference

14. Why Monitor?
Why?
Because Batteries Fail! Batteries are like humans. Sooner or later the battery will reach end of life. It can happen through…
“Normal” aging
Positive Grid Corrosion
Pre-mature failure
Manufacturing defects
Battery “abuse”
High temperature
Excessive charge current
Defective chargers
Damaged battery jars

15. It only takes one bad cell to bring a string down
Avoiding costly down time
Why?
0 V
480V
It only takes one bad cell to bring a string down

16. Fixed installed leads captures test data the same way, every time.
Reliable test data
Why?
Fixed installed leads captures test data the same way, every time.

17. Reliable test data
Why?
Pre-mature failures develop faster. Monitoring will detect problems earlier.

18. Why? Why monitor? Increase battery system reliability Cost savings
Avoiding costly unplanned down time
Reliable test data through consistent data acquisition
Cost savings
Reduced maintenance cost or redirection of crew to perform proactive maintenance
Optimizing battery life
Often double useful battery life

19. Why? Cost savings Optimize battery life
Monitor critical parameters and take appropriate action
Internal resistance
Replace bad cells before they affect other cells
Maintain a balanced resistance level in all redundant strings
Temperature
Temperature has a direct influence on battery life
Uneven temperature over the string cause cells to float differently
Voltage
Charge voltage should be matched to ambient temperature
Float current
Improper ripple affects the battery life

20. Why? Why monitor? Increase battery system reliability Cost savings
Avoiding costly unplanned down time
Reliable test data through consistent data acquisition
Cost savings
Reduced maintenance man-hours or redirection of maintenance crew to proactive maintenance activities
Optimizing battery life
Safety
Limiting personal hands-on and avoiding human errors
Avoiding catastrophic battery failures

21. Detect problems before they cause a catastrophic system failure!
Safety
Why?
Detect problems before they cause a catastrophic system failure!

22. Increase Reliability How?
Most monitors will be able to detect a failed battery by...
monitoring overall voltage or individual cell voltages during discharge
if the discharge is long enough to show a drop in voltage
trending increased cell impedance
if the charger noise is low, if the system load is constant and if no cells are replaced

23. Increase Reliability How?
Most monitors will be able to detect a failed battery by...
monitoring overall voltage or individual cell voltages during discharge
if the discharge is long enough to show a drop in voltage
trending increased impedance or conductance…
if the charger noise is low, if the load is constant and if no cells are replaced
But it’s a gamble! The battery may FAIL during the next outage because the chosen technology does not alert you to the problem early enough!

24. How? Increase Reliability
What is needed to detect a failing cell before it cause a problem?
We have to detect problems in the conduction path
Internal to the cells
Inter-cell connections.
Internal resistance is directly related to the battery cells capability to generate power

25. How? Ohmic measurements
The following terms are used, in the battery industry, to describe internal ohmic measurements :
AC Impedance (Z)
AC Conductance (Siemens)
DC Resistance
These are the three different terms used in connection with Ohmic measurements.
Please note that AC Impedance should be simply called Impedance. The definition of Impedance is opposition to AC current flow. Therefore AC Impedance is redundant
AC Conductance is not correct; the definition of Conductance is the inverse of Resistance. The commercially available AC Conductance meter actually measures the same thing as Impedance except it inverts the answer. In this presentation it will be treated as an Impedance meter.
The presented value and entity is not the issue, it‘s a question about AC vs. DC based measurements

26. Cell Resistance
If a 2 V Cell’s internal resistance increases more than 25% above its baseline value, that Cell will not pass a 3 hour capacity test. It may pass an 8 hour capacity test but it will NOT pass a 30 min capacity test
Capacity
Most battery manufacturers base their warranty settlements on a 50% increase in the ohmic value and as will be pointed out later, that is not a valid number for maintaining a reliable battery system.
Resistance

27. Internal resistance
Why is internal resistance related to battery capacity and why is it important to use an appropriate measurement method?
New Grid
Aged Grid

28. Select illustration for
Push on the button below to jump to the illustration you prefer
Electrical Engineers
Non Electrical Engineer

29. Simplified equivalent circuit
The conduction path through a battery includes the:
Resistance of the Post, Strap, Grid, Grid-to-Paste, Paste, Electrolyte, Separator and so on...
This is the generally accepted simplified circuit equivalent circuit of a lead acid cell

30. Simplified equivalent circuit
The conduction path through a battery includes the:
Resistance of the Post, Strap, Grid, Grid-to-Paste, Paste, Electrolyte, Separator and so on...
The cell also has a huge capacitor C
This is the generally accepted simplified circuit equivalent circuit of a lead acid cell

31. Simplified equivalent circuit
The conduction path through a battery includes the:
Resistance of the Post, Strap, Grid, Grid-to-Paste, Paste, Electrolyte, Separator and so on...
The cell also has a huge capacitor
This capacitor is connected in parallel over about 45% (R2) of the total resistance
R1~55% C
R2~45%
This is the generally accepted simplified circuit equivalent circuit of a lead acid cell

32. Simplified equivalent circuit
The conduction path through a battery includes the:
Resistance of the Post, Strap, Grid, Grid-to-Paste, Paste, Electrolyte, Separator and so on...
The cell also has a huge capacitor
This capacitor is connected in parallel over about 45% (R2) of the total resistance
It is this capacitor in parallel over a part of the resistive path that constitutes the difference between AC and DC measurements!
R1~55% C
R2~45%
This is the generally accepted simplified circuit equivalent circuit of a lead acid cell

33. AC Measurements The Ohmic value of a capacitor depends
on the size of the capacitor and the
frequency of the test current.
XC=1/2fc
The higher the test current frequency and
The bigger the capacitor, the smaller the
ohmic value of the capacitor.
The typical capacitance value of a Cell is 1.5 Farads per 100 A-hr of capacity.
The typical test frequencies used by the present test equipment manufacturers ranges from 20 Hz to 1000 Hz.

34. AC Measurements
When applying an AC test current over this circuit, the capacitor becomes a partial short circuit around part of the resistance path.
The applied AC test current signal will follow the path of least resistance and therefore mask rising problems in the important R2 path
R1~55%
R2~45% C
As the ohmic value of the capacitor approaches values that are close to 60% of the baseline value of R2 it becomes practically impossible to detect any increases in the R2 part of the path

35. Typical Cell problem, detected by increased resistance.
Paste breaking away from grid causing increased resistance primarily in the R2 path.
This picture shows a positive lead calcium plate that is approximately 15 years old.
Note that the grid has grown due to corrosion, which takes place gradually as the battery ages. The paste pellets are breaking away from the grid structure, causing a high resistance connection between the grid and the paste.
New Grid
Aged Grid

36. Circuit Analysis R1 = 110μΩ C = 15F R2 = 90μΩ
We will use the below formula to calculate the Impedance if the resistance values in R1 respectively R2 changes
R1 = 110μΩ
C = 15F
R2 = 90μΩ
So now let us analyze the difference between AC measurements and the true Internal Resistance.
Guideline for Capacitance is 1.5F / 100Ah. Example 2000Ah = 30F
This example shows typical values of Baseline Resistance and Capacitance for a 1000 A-hr Cell.
Using this model, we will examine what the impedance of the circuit is for the values shown and then we will calculate what the impedance readings are for different failure modes. We will assume that R2 increases enough to cause the total resistance to increase by first 25% and then 50%.
We will then see what happens as R1 fails
Typical 1000 Ah cell

37. % Change Rtot from baseline % Change Ztot from baseline
R2 vs. Rtotal and Ztotal
Test Freq
Cell failure
Rtot
R1+R2
% Change Rtot from baseline
Ztot
% Change Ztot from baseline 60
None
200 
185 
R2 > 140
250  25
208  12
R2 > 190
300  50
220  19
200
139 
135 
-2.2
133 
-4.0
The analysis comes up with some interesting answers; Note that the Impedance of a known good cell always reads less than the Resistance. Also note that if the total Resistance increases by 25% as a result of R2 increasing, the corresponding increase in Impedance at 60 Hz is only 12%. The change in Impedance at 200 Hz is actually a decrease.
This shows that Test Equipment or Battery Monitors using these frequencies will actually declare a bad cell good. The problem with using Impedance as a State of Health Indicator gets even worse if the 50% above baseline criteria is used.

38. % Change Rtot from baseline % Change Ztot from baseline
R1 vs. Rtotal and Ztotal
Test Freq
Cell failure
Rtot
R1+R2
% Change Rtot from baseline
Ztot
% Change Ztot from baseline 60
None
200 
185 
R1 > 160
250  25
234 
26.5
R1 > 210
300  50
284 
53.5
200
139 
187  35
236  70
This table shows what happens if the total resistance increases as a result of R1 increasing.
At 60 Hz there is only a small error introduced, but at 200 Hz the Impedance reading goes way high and exaggerates the problem. This means that using a 200 Hz device will cause good cells to be declared bad well before they reach their Resistance failure level.

39. Noise
Typical AC Ripple riding on a 2 volt UPS Cell
Ripple voltage is ~40mV or 40,000µV.
Most AC instruments inject a 1 A AC test signal which will generate a 300µV signal through a 300µΩ cell
This means that the test instrument will have to accurately resolve a 300µV signal in 40,000µV ripple noise!
1A * Ω=0.0003V
This is an oscilloscope presentation of the ripple voltage present on a 2 volt UPS battery with a baseline internal resistance of 300 micro-ohms. Note that the ripple voltage is around 40 millivolts peak to peak that is 40,000 micro-volts. A 1 amp square wave AC instrument would only generate a peak to peak voltage of 300 micro-volts. That gives you an idea of the signal to noise ratio.

40. Resolution/Test current
Example:
The Resistance of a 1000 Ah cell is 200 .
25% increase of resistance designates a bad cell which means that the test instrument has to detect an increase of 50 to 250.
In order to accurately measure this increase, the instrument needs a resolution of 10% of the measured value.
This means that a 1 amp test instrument will have to resolve 5 V to detect a cell turning bad!
That’s a very expensive voltmeter…
Low current instrument may yield reasonable readings on very small high resistance batteries such as 12 volt modules, but cannot realistically be used on large 2 volt cells.
1000Ah = 200microohm + 25% 250microohm , 50mocroohm over 1 A equals 50microvolts. In order to measure 50microvolts accurately a voltmeter will need the capacity to resolve 5microvolts. Standard Fluke voltmeters can typically only measure down to 0.1mV.

41. How are Resistance Measurements made?
The instantaneous voltage drop at time zero and when the load is removed shows the voltage drop across the internal resistor
Resistance = V/I
So if we measure the test current flowing and the corresponding change in voltage, then we can simply solve ohms law to calculate the internal resistance.

42. Ohmic measurements
Alber’s Internal Resistance measurement method is superior because of the following reasons.
Eliminates the “capacitor effect”
Not affected by ripple or noise
superior resolution and repeatability
These are the three different terms used in connection with Ohmic measurements.
Please note that AC Impedance should be simply called Impedance. The definition of Impedance is opposition to AC current flow. Therefore AC Impedance is redundant
AC Conductance is not correct; the definition of Conductance is the inverse of Resistance. The commercially available AC Conductance meter actually measures the same thing as Impedance except it inverts the answer. In this presentation it will be treated as an Impedance meter.

43. Case Study
How does a failing cell look like and how can we detect and prevent a catastrophic failure?
The following case study Illustrates how the Alber monitor detects a failing cell and how a discharge test confirm the internal resistance reading.

44. Playback
The following slides show an internal resistance test and then an actual 20 min battery discharge with the playback accelerated
It is a battery string consisting of volt jars.
One of the cells in jar 41 fails.
The real time display ability during the discharge confirms the resistance test results.

45. This is an indication of a bad cell within this jar.
The 941 micro-ohm value of Jar 41 is 22% higher than the other jars in the string and has triggered an alarm turning the bar red.
This is the results from the automatic resistance test. It’s a string consisting of 60 8-volt jars.
This is an indication of a bad cell within this jar.

47. Now we will step though the discharge.

48. At 13 min jar 41 begins to fall off.

49. At 17 minutes jar 41 is 4.99 volts and the test is aborted.

50. Note that jar 41 is now floating with rest of the jars.
By 18 minutes, the charger has walked back in and there is 90 amps of charge current.
Note that jar 41 is now floating with rest of the jars.
Without the internal resistance alarm, real time capture and storage, this failing cell would have been overlooked and left in service only to fail during an outage!

51. How? Confirming the data
We verified the data from the resistance test in a discharge test.
Knowing how each individual cell performs during a discharge can be crucial. High scan rate is important

52. Auto Discharge Capture
How?
Most power outages that occur are less than 30 seconds.
Most monitors cannot record cell voltages in these short events because their scan rate is too slow. This prevent them from capturing discharge events which provides important information.

53. Remember: A battery is only as good as its weakest cell.
Conclusion
Make sure you select a monitor that will provide you with correct information
Correct and accurate parameters as described in this presentation
Auto capture of discharge events
Real time display with high scan rate (<10 sec)
Make sure your maintenance crew attend a Basic Battery Training
Remember: A battery is only as good as its weakest cell.

54. Battery Monitors BDS-256 Battery Diagnostic System
UL Certified
CE Approved
Monitor any battery system up to 600 volts DC
UPS systems
Generating stations
Industrial

55. Parameters Monitored Overall voltage Discharge current
Charger float current (optional)
2v cells, NiCad cells, 4v, 6v, 8v and 12v modules
Temperature
Resistance of all cell/jars, intercells, and intertiers

56. System Level I/O System inputs System outputs (form C contacts)
Remote alarm reset
16 digital inputs
System outputs (form C contacts)
Maintenance alarm
Critical alarm
8 programmable control outputs(BDS-256)

57. Communication Two RS-232 for local computer RJ-11 for telco dial up
RJ-45 for Ethernet connection
Standard Modbus protocol

58. BDS Controller The “Brain” that control the system.
Collects and stores data from the DCMs
Microprocessor driven
Stand alone – No on site PC required.
8 strings of 256 cells per Controller

59. Data Collection Module (DCM)
The Data Collection Module acquires all readings from the battery
48 cells or modules
2 temperatures
Discharge current
Charger float current

60. External Load Module Supports proactive DC internal resistance testing
One ELM for each string
Tests battery in 10% increments
Test current approximately 30 amps

61. Configuration examples
3 strings, 40 jars, 12V per jar
1 DCM and 1 ELM per string
1 CT and at least 2 temperature probes per string
1 controller
String 1
String 2
String 3

62. Configuration examples
2 strings, 240 jars, 2V per jar
5 DCM’s and 1 ELM per string
1 CT and at least 2 temperature probes per string
1 controller
String 1
Fiber optics for data transfer and power supply between DCM and Controller
String 2

63. Ease of Installation
Modular design allows the DCMs to be located near the battery, reducing wire lengths
One 120 vac power connection required for up to 8 strings of 256 cells.

64. BDS-256 Installation
Mounted on top of MGE 6000 Cabinet

66. MPM-100 Designed for applications below 130VDC UL and CE approved
More than 100 battery configurations available
Monitors 1 string of 120VDC or up to 4 strings of 12, 24 or 48VDC
Modbus protocol
Powered from DC bus or 115VAC
Network, Serial, Modem connection options

67. Alber the total solution

68. MPM installation

69. Thank you
Press ESC to exit

70. Pipe analogy
A healthy battery will produce power and allow easy flow of DC current.
The more power that is required, the more power will be produced
When the fuel is gone, it has to be charged

71. Aging As the battery ages, the capacity diminishes.
It is as if the pipe has clogged up.
It cannot produce the desired capacity

72. AC based testing
A battery has a huge built-in capacitor (Parallel plates)
Capacitor will allow AC current to flow but will block DC current
When testing with AC the battery may look healthy as the AC test current will pass through capacitor

73. DC based Testing Alber’s DC test does not look at the AC path
It measure the battery’s resistance under normal working condition
This makes it possible to assess the health and detect early signs of degradation

74. Test current
Ohm law (V=I*R) dictates that low current over a low resistance will result in low voltage.
Low test current will not allow for accurate measurements.
Resolution above +/-100microOhms will not detect failing cells with more than 500Ah capacity

75. Test current
The Alber monitor use 30A-70A of current to allow for an accurate reading.
The Alber test method is repeatable and accurate.
Alber internal resistance test equipment can test any battery design in increments of 1µΩ

76. Noise The UPS battery is a noisy environment
Using low test current is like a conversation with someone with low voice in a noisy bar
Would you choose that environment for a discussion where attention to details are vital?

77. Return