1. Energy Storage & Stationary Battery Committee
Performance Testing Lead-Acid Stationary Batteries;
Myths, Misunderstandings and Mistakes
Rick Tressler
Sr. Training Engineer
Alber
IEEE PES
Energy Storage & Stationary Battery Committee
Sunday Technical Sessions
June 12, 2016

2. Presentation Topics Myths Misunderstandings that Lead to Mistakes
Negative effects of performance testing
Equalizing a VLA battery before a test
Equalizing a VRLA battery prior to a performance test
Misunderstandings that Lead to Mistakes
Test termination at 100% capacity
Failure to bypass weak cells
Load bank cable sizing
Test termination at first cell final voltage
High rates on small connectors

3. Myths

4. Myth #1 Performance testing ruins a battery
A lead calcium, flat plate, S.G. battery can deliver about 50 cycles to 80% DOD when tested at the 5 hour rate to 1.75 VPC
IEEE based testing results in about 6 cycles to about 50% DOD
Test at 1 to 2 hour rate at the corresponding higher current instead

5. Myth #1 (continued) Example test schedule
Test #1 Acceptance test at installation
Test #2 Performance test within 2 years of installation – weeds out early failures
Tests #3-5 Performance test at 5 year intervals (20 year expected service life)
Test #6 Begin testing annually until reaching 80% rated capacity

6. Myth #2 Always equalize a VLA battery before a test What kind of test?
It’s appropriate prior to Acceptance tests
Equalize charging when new is termed Initial, Commissioning or Freshening charge
No less than 3 days but not longer than 30 days on float prior to testing after completing charge

7. Myth #2 (continued) Performance testing?
Do not equalize unless the intent is to baseline/benchmark capacity (Acceptance test)
Usually performed to reflect maintenance practices
Batteries do not get equalized before an emergency outage occurs

8. Myth #2 (continued) The elusive “72 hour” equalize before a test rule
Where did it come from?
Probably the result of some urban battery legend
Equalize a battery for 72 hours, regardless of type, size, application, then run a test – NO!
There is no one-size-fits-all equalize procedure

9. Myth #2 (continued)
Table clearly indicates the equalize time varies widely

10. Myth #3 Equalize VRLA batteries prior to a Performance test
This should not be conducted unless specifically indicated by the battery manufacturer
Generally part of the commissioning procedure only

11. Misunderstandings

12. Misunderstanding #1
Terminating a Performance Test When Battery Capacity Reaches 100%
Example 58 cell battery
Published time -1 hour rate
Published final voltage – 1.75 VPC
Battery final voltage should be V

13. Misunderstanding #1 (continued)
Oops!
Should be 101.5

14. Misunderstanding #2 Failure to bypass weak cells
Testing with a failed cell in the circuit prior to 90%-95% of expected time can skew test results
Before 90%, discontinue or pause the test, bypass the cell, then resume

15. Misunderstanding #2 (continued)
Cell failure occurs later than 90%-95%?
Continue the testing to the specified final battery voltage
Caveats
Bypassing cells is allowed once during a test
Maximum downtime to be not longer than 10% of test time or 6 minutes, whichever is shorter

16. Misunderstanding #3 Failure to Correctly Size Load Bank Cables
Voltage drop must be considered when load banks are being operated near or at full load rating
May not be able to achieve required load current
Cable overheating also a concern

17. Misunderstanding #3 (continued)
Example
Cable Size (CM) = × loop conductor × load ÷ max drop
12.9 × 100 × 450 amperes ÷ 3.0 v
Cable size = 193,500 CM (4/0 cable, 211,600 CM) – 1 conductor per polarity recommended

18. Misunderstanding #4
Terminating a Test When the First Cell Reaches Final Voltage
Such action renders the test invalid
Test termination criteria is the point in the test when overall battery voltage occurs, not when the first cell reaches the average end-of-discharge voltage

19. Misunderstanding #4 (continued)
Cell voltages vary during discharge
Perfect uniformity is not achievable
There is always cell voltage variation

20. Misunderstanding #5 High Test Currents with Small Intercell Connectors
8 hour battery tested at the 1 to 2 hour rate
Exercise caution; avoid excessive voltage drop and possible overheating of connectors
Consult battery manufacturer if in doubt
Do no harm to the battery

21. Summary Testing requires a good understanding of batteries
Proper technician training is essential
An understanding of the applicable IEEE recommended practice should be more than casual
Maintain copies of current standards in your digital library
Documented procedures are extremely useful
Seek answers to questions before testing
Be prepared for the unexpected

22. Energy Storage & Stationary Battery Committee
Performance Testing Lead-Acid Stationary Batteries;
Myths, Misunderstandings and Mistakes
Rick Tressler
Sr. Training Engineer
Alber
IEEE PES
Energy Storage & Stationary Battery Committee
Sunday Technical Sessions
June 12, 2016