With improvements in battery technology, the range of applications in portable devices is growing rapidly: not only portable telephones, but also video cameras, notebook computers, and other electronic devices. But the performance of these devices depends on the lifetime and performance of the batteries. Because of the wide variation in battery lifetime depending on the charging frequency and pattern of use, an increasing demand for battery maintenance tools can be expected. The 3555 BATTERY HiTESTER provides a simple, on-the-spot assessment of the state of compact storage batteries, including nicad (Ni-Cd) and nickel metal hydride (Ni-MH) batteries.
Simultaneous measurement of resistance and voltage
This tester uses the same AC four-terminal method* as Models 3550 and 3551 use for lead-acid batteries to measure the internal resistance, and simultaneously measures the battery voltage, to give an immediate Pass/Warning/Fail result.
* The AC four-terminal method supplies an AC current from the source terminals to the battery being measured, and measures the voltage drop with the sense terminals. This cancels out the contact resistance and lead resistance, and provides accurate measurement of low resistances. See also the enlarged illustration of the tip of the 9461 Pin-Type Leads.
Three-rank rating of battery state: Pass, Warning, or Fail
The Pass/Warning/Fail assessment of a battery's state is based on a six-way combination of comparisons against upper and lower resistance limits and a voltage threshold.* This result is then indicated by LEDs and a beeper. * The comparison threshold values depend on the battery manufacturer, type, and capacity, and these must be established by the user.
Simple operation
Once the appropriate comparison values for the battery being tested have been entered or recalled from memory, measurement is as simple as contacting the pin-type probes against the battery terminals. Since the tester is battery-operated, it can also be used anywhere.
Battery diagnosis
Once a compact storage battery, typically one used in a portable telephone, exceeds the manufacturer's guaranteed limit on charge-discharge cycles, its charging capacity gradually deteriorates, and the operating time on a single charge may become extremely short. A simple test is therefore required to determine whether an apparently faulty instrument simply has a failing battery. In cases such as these, the 3555 BATTERY HiTESTER gives exactly the guidance needed to determine whether or not to replace the battery.
The increasing importance of battery testing
With the advancing information age, UPS applications will become important over a wide range of locations, from office buildings to hospitals and research institutions. Accordingly, battery maintenance is a field that can be expected to grow in importance. Also, in the development of practical electrically powered vehicles, the environment for lead-acid storage batteries is changing rapidly, and these changes indicate a great opportunity for the Models 3550 and 3551 BATTERY HiTESTERS.
What about conventional maintenance methods?
The conventional technique for checking the state of a backup battery is based on a measurement of the specific gravity of the electrolyte. But as sealed batteries have become the most common type, this is no longer possible. The 3550 and 3551 take measurements from the battery terminals, and can therefore function with completely sealed batteries.
Relationship between charging time and charge capacity or internal resistance
The operational life of a battery depends on the frequency of use (number of charge/discharge cycles). The graph on the right illustrates the relationship between the time required for charging the battery and the charge capacity and internal resistance, and shows that as the charging time increases, the charge capacity decreases, and also the internal resistance rises.
There are various methods for determining whether a battery has reached the end of its operational life, but the method based on measuring the internal resistance and voltage is fast and reliable.