What Is a Cell and Battery Tester? Types and Selection Criteria
A cell and battery tester is a measuring instrument that quickly shows the health of a cell or battery by measuring its terminal voltage and internal resistance.
A cell and battery tester is a measuring instrument that quickly shows the state of health of a cell or battery by measuring its terminal voltage and internal resistance. It is used in the periodic maintenance of UPS and telecom battery banks, in vehicle battery service, and in production or incoming quality control of lithium cells.
Types of cell and battery testers
| Type | Measures | Where it is used |
|---|---|---|
| Handheld internal resistance tester | Terminal voltage and internal resistance | Block-by-block field checks of UPS and telecom battery banks |
| Vehicle battery tester | Voltage, cranking performance and state of health of a 12 V battery | Car service, fleet maintenance |
| Benchtop battery tester | Voltage and internal resistance, pass-fail sorting | Lithium cell production, laboratory and incoming quality control |
A multimeter shows only the terminal voltage. A battery whose voltage looks normal may have a raised internal resistance; a battery tester that measures at the milliohm level reveals it.
Selection criteria
- Voltage range: The tester's upper limit must be higher than the voltage of the cell, block or pack to be measured. In the catalogue, the UT677A+ covers 0–70 V and the UT677C 0–120 V.
- Internal resistance range and resolution: Large-capacity batteries and lithium cells have internal resistance of a few milliohms or lower; the tester's lowest range and resolution must be able to read that level.
- Battery type: The vehicle battery testers in the catalogue are for 12 V starter batteries. On these testers you usually select the cold cranking amps (CCA) value and standard printed on the battery label.
- Recording and interfaces: Field maintenance may require saving readings, reporting or printing; the UT675A has a printer. For automatic sorting on a production line, the benchtop UT3562 and UT3563 with a Handler output and RS-232, USB and SCPI or Modbus support are suitable.
- Probe type: For milliohm measurement, four-terminal (Kelvin) probes keep tip and lead resistance out of the result.
Common mistakes
- Looking only at voltage: An ageing battery keeps a normal voltage for a long time while its internal resistance rises.
- Comparing values from different batteries: Internal resistance depends on capacity, type and temperature. Compare with a new battery of the same model or with the other blocks in the bank.
- Measuring right after charging: Surface charge makes the voltage read high; measure a rested battery.
- Exceeding the voltage limit: If the total voltage of a series string exceeds the tester's range, measure the blocks one by one.
Cell and battery testers in the catalogue
The Cell and Battery Testers category has 7 active Unit models:
| Type | Model |
|---|---|
| Handheld internal resistance tester | UT677A+ (0–70 V), UT677C (0–120 V) |
| Vehicle battery tester | UT673A, UT675A (with printer) |
| Benchtop cell and battery tester | UT3562, UT3563 |
| Cell and battery tester | UT3550 |
The UT673A is priced and can be ordered directly; the other models are priced on quotation with lead time. UPS battery cabinets are in UPS Accessories and Battery Cabinets, multimeters for general voltage measurement in Digital Multimeters, and other testers in Electrical and Electronic Testers.
Frequently asked questions
Why is battery internal resistance measured?
As a battery ages, sulphates or dries out, its internal resistance rises and it can no longer hold its voltage under load. Periodic internal resistance measurement finds the weakening block before a failure.
Can a battery be tested with a multimeter?
A multimeter measures only the terminal voltage. To judge whether a battery can deliver load, you need a battery tester that measures internal resistance or cranking performance.
What is the difference between a vehicle battery tester and an internal resistance tester?
A vehicle battery tester interprets the health and charge of a 12 V starter battery against its CCA rating. An internal resistance tester measures voltage and internal resistance as numbers on UPS, telecom and lithium cells.
How do I test a UPS battery bank?
Measure the blocks one by one, record the values and compare them with the other blocks in the bank or with earlier readings. A block with clearly higher internal resistance is a candidate for replacement.