Battery maintenance, charging & testing
Batteries – Typical Applications
- Electric generating stations and substations for protection and control of switches and relays
- Telecom systems to support phone services, especially emergency services
- Industrial applications for protection and control
- Back up of computers, especially financial data and information
- Automotive Industry
Standards defining different battery models testing
Battery Monitoring standard
Nickel-Cadmium (internal resistance test not recommended)
Valve-regulated Lead Acid (VRLA)
Vented Lead Acid batteries (VLA)
Lithium
Battery Test Types
- Visual inspection
- Specific gravity (SOC test)
- Float voltage and current
- Individual cell condition
- Internal resistance
- Capacity test
Condition assessment parameters
Capacity (Ah)
- The most important parameter for condition assessment
- The only 100%-reliable method to test your battery (slow, but safe).
- The key test according to IEEE standards.
- Acceptance test
- Periodically
- If we suspect there is a problem
HOW?
- Fully charged battery (up to nominal or maximum voltage)
- Connect battery to battery discharger
- Test parameters settings
- Current / power / resistance
- Time
- Limits (voltage, capacity...)
- -> After 10h (usually), the result is :
- The result is a number: C = I x t (Ah)
- Example:
- Manufacturer: C10 = 1200 Ah
- Measured: CM10 = 1134 Ah (94,5%)
Good?
- Yes, because 80% limit not reached (960 Ah)
- 94,5% Ah capacity is still there
What is a “good” battery
Voltage measurement
- Simple
- Unreliable information on battery condition
- Good voltage ≠ good battery
MEASURING CELL VOLTAGES
- Increase the string life time (replace only the bad cells)
- Predict string failures caused by individual bad cells
- Reduce risk of replacing the string too early
- Remove the weak cells
2 Ways
- MANUAL
- Requires periodical human engagement
- AUTOMATIC
- No human engagement during test