Batteries provide power for portable electronic devices. They come in many shapes and sizes, from tiny cells that power pocket-sized personal electronic devices to large, fixed systems. They are also available in different chemistries, such as alkaline, lead-acid, and lithium-ion cells. Each battery chemistry results in battery cells with different voltages, such as 1.5 V for alkaline cells, 2.0 V for lead-acid cells, and 3.0 V for lithium cells. Commercial batteries are typically comprised of multiple connected cells to achieve higher voltages, such as 12 or 24 V. Batteries are obviously essential components in any portable electronic product or system, and should be tested to determine performance and quality, whether in production or as part of a regular maintenance schedule. Testing may involve measurements as routine as voltage and current or more complicated, such as variations in voltage as a function of temperature and/or vibration. In each case, measurements made with the appropriate test equipment can help extend the operating lifetime of a battery and provide fair warning when a battery or battery pack needs to be replaced.
Several basic electrical parameters provide insight into the health of a battery, including voltage, current, and resistance. More elaborate tests, such as measurements of voltage ripple or variation in a battery’s voltage with time or temperature, can be used to reveal details about a battery’s performance capabilities. The simplest battery tests, such as measurements of voltage, can be performed with the simplest of test tools, such as a portable multimeter or voltmeter while more elaborate measurements, including automated analysis of test results, require more sophisticated test instruments, such as dedicated battery analyzers. In a battery manufacturing test application, for example, some of the more important tests include open circuit voltage and AC resistance and a test instrument such as an automated battery analyzer capable of making these measurements on battery cells quickly and accurately, while providing the means to upload test data to a computer or data base by means of wired Ethernet or USB interconnection or even a wireless interconnection, such as a WLAN.
Rechargeable batteries require some specialized measurements to determine the charge capacity of a battery and its cells and, possibly, its expected operating lifetime based on the number of recharge cycles. This is done by performing discharge-charge cycles on a battery, during which the current frequency and harmonic content of the charger can also be measured. Such measurement capabilities call for a test instrument with both analysis and power source capabilities.
Finding a Tester
Test instruments for checking batteries are designed for different types of measurement applications, such as whether measurements are to be performed on a production line or on individual batteries or battery packs or banks. An instrument as basic as a voltmeter or multimeter can be used within its operating range to measure the voltage of a battery one at a time using its connected test leads, but it may not be capable of providing any more information about the health of the battery. For much greater measurement capability, an instrument such as the Fluke BT521 Advanced Battery Analyzer is ideal for a wide range of measurements on stationary batteries, including AC and DC voltage, AC and DC current, ripple voltage, and battery temperature. It can be used manually or automatically, using built-in software. The analyzer is designed for ease of use, with an operator’s interface that guides a user through the test setups for different measurements. Physically, the instrument includes easy-to-grip positive and negative test probes with long tips to make connections on even the hardest-to-reach installed batteries.
The Fluke BT521 is an excellent fit for battery maintenance measurement applications, with a simplified workflow that can be programmed by a user to follow any required sequence of battery measurements. As many as 10 sets of upper and lower measurement thresholds or tolerance limits can be set in the analyzer for flexible pass/fail battery testing, with measurements automatically compared to selected thresholds. For ergonomic ease, the analyzer can be used with an intelligent test probe that features an integrated liquid-crystal-display (LCD) screen that can show at a glance, for example, the results of battery temperature, resistance, and voltage measurements.
The Fluke BT521 is a lightweight (1.9 lbs.) and compact (9 ×4 × 2 in.) portable instrument with a mini USB connector for downloading test results to a personal computer (PC). It has a 600-V voltage measurement range with 0.1-V resolution and a 3000 m? resistance measurement range with 1-m? resolution. The companion Fluke Battery Measurement Software runs on a PC and allows a user to store profiles of different batteries, compare results, perform trend analysis, and generate detailed results for multiple battery tests.
Another compact battery tester, the Keithley 2306 Dual-Channel Battery Charger/Simulator, is well suited for characterizing portable battery-powered designs. For battery testing, it offers an output range of 0 to +15 V DC with accuracy of ±0.05% + 3 mV; output voltage can be set with resolution of 1 mV. For realistic testing, the 2306 can vary the resistance of its output ports to simulate the response of a battery to different loads. When high-power test capabilities are required, the Keithley 2260B-80-13 programmable power supply is rated for as much as 80 V DC voltage, 13.5 A current, and 360 W output power per unit, but multiple supplies can be connected in series or parallel to achieve as much as 2160 W output power.
When the flexibility of a modular instrument is needed, the Keysight N6705B power analyzer can adjust capabilities when equipped with different modules, with power ratings from 50 to 500 W. Although this is a full-sized, rack-mountable instrument with or without modules, it is a complete battery and power-supply measurement system, integrating multiple power supplies, DMM, oscilloscope, arbitrary waveform generator, and data logger into a programmable (GPIB, LAN, and USB) mainframe that can hold as many as four modules to handle as much as 600 W total power. It provides as much as 18-b accuracy for voltage and current measurements, with 0.025% + 50 µV voltage measurement accuracy and 0.025% + 8 nA current measurement accuracy. It includes 1 GB of nonvolatile data storage for saving instrument settings and test results.
Also modular, but larger and more powerful, the NH Research 9200-4904 Battery Tester is a workhorse. At 72 in. high and 26 in. wide, this is a full-scale battery test system designed for fixed testing applications, such as in laboratories and production lines. It provides several charge-discharge modes, including constant voltage, constant current, constant power, and constant resistance. It orchestrates precisely controlled charging and discharging cycles, with charging envelopes from 0 to 40 V and as much as 600 A current and 8 kW power and discharging envelopes from 1 to 40 V and as much as 600 A current and 12 kW power.
In normal use, batteries are connected to some form of load, such as a mobile electronic communications device, and that load will have a great deal to do with the recharge cycle and operating lifetime of a battery. Fortunately, programmable electronic loads are instruments that enable DC testing of a battery’s response to different loads and surge voltage requirements. Instruments such as the Chroma 63600-5 programmable electronic load mainframe when equipped with the appropriate load modules can provide as much as 2 kW output power. A 63600-5 mainframe can hold as many as five DC load modules designed for constant voltage, constant current, constant power, or constant resistance testing with 16-b precision. Modules include the dual-channel Chroma 63610-80-20, rated for maximum output power of 100 W. It controls voltages from 0 to 80 V DC with three operating current ranges of 0 to 0.2 A, 0 to 2 A, 0 to 20 A.
Additional, single-channel, modules include the Chroma 63630-80-60, with maximum ratings of 600 W, 80 V, and 60 A; the model 63630-600-15, with maximum ratings of 300 W, 600 V, and 15 A; the Chroma 63640-80-80, with maximum ratings of 400 W, 80 V, and 80 A; and the model 63640-150-60, with maximum ratings of 400 W, 150 V, and 60 A. Each module can be operated independently, or modules can be synchronized to generate almost unlimited test conditions. With the capacity and flexibility of the Chroma 63600-5 mainframe, users can mix and match modules as needed to suite the requirements of a battery or power supply test application.
In a world “gone mobile,” batteries have become as important as the electronic devices (such as smart phones) that they power. Whether for production line testing or regular maintenance measurements, high-quality battery test equipment is available from a number of suppliers. For more details on these and other test equipment available, browse the rest of Axiom Test Equipment's website at www.axiomtest.com, or contact Axiom's sales department at email@example.com or call an Axiom account manager at 760-806-6600.