Bolster Battery Performance With Proper Measurements

Batteries provide the power for portability, from the miniature rechargeable batteries of cellular phones to the larger battery packs of electric vehicles (EVs) and hybrid electric vehicles (HEVs). Ideally, rechargeable/regenerative batteries provide long operating lifetimes; with long discharge cycles and short recharge times. To determine performance levels, rechargeable secondary batteries must be tested for a number of meaningful parameters with the appropriate measurement equipment. Testing can tell such details as how well a battery can hold its charge in terms of voltage, current, and power, how efficient it is, and how effectively it can be recharged.

Rechargeable batteries of different chemistries, such as lead-acid, nickel-cadmium (Ni-Cd), and lithium-ion (Li-ion) types, are used as power sources in modern electronic products. They must handle many different kinds of loads in those products, under many different operating conditions. The most complete battery test systems try to simulate the conditions under which batteries will be charged and discharged during normal operation. To do this, a test system must perform measurements on a rechargeable battery’s standard characteristics, including voltage, current, and power, but also on functions pertinent to regenerative batteries, such as charge rate, discharge rate, and state of charge.

Requirements for a test system will vary according to the size and capacity/power of a battery pack to be tested, and whether testing is for the laboratory or the production line. Modern battery test systems may have maximum voltage ratings from 20 to 25 V to hundreds of volts. Such testers are true systems with multiple test functions, including power supplies and power analyzers. They are capable of providing the stable power source needed for recharging a battery, the means of safely discharging a battery with effective thermal control, and a multiple-function power analyzer that can quickly and precisely measure voltage, current, power, and even calculate battery source resistance.

Larger batteries require test systems with higher voltage, current, and power ratings and, for flexibility, some regenerative battery test systems are designed with modular formats that allow users to add test modules to a mainframe to increase the capacity of the measurement system. Test systems designed for production testing will usually provide multiple independent test channels for simultaneous testing of multiple batteries. Compared to laboratory test systems, production regenerative battery testers will also stress high-speed measurement functions, such as minimal transition times between discharge and charge cycles when testing a battery.

One example of an accurate and versatile Regenerative Battery Test System is the NH Research 9200 series multi-channel and 9210 single-channel Automated Regenerative Power Battery Test Systems. The NHR battery testers provide the power, performance, and functionality to test a wide range of secondary batteries and storage modules, including standard car batteries, electric bicycle and scooter batteries, and EV batteries.

The NHR 9200 series systems incorporate a host of safety features, including polarity check, over-voltage, over-current and over-temperature protection. The efficient system provides the capability to return energy from the discharged batteries, back to the AC power mains with high efficiency (87% efficient).

It can perform battery characterization under constant voltage, constant current, and constant-power condition. It can be used to characterize all regenerative battery chemistries, including lead-acid, Ni-Cd, and Li-ion batteries.

Battery packs that consist of many Li-ion cells will need to be “conditioned”; that is, each cell must be adjusted to the same capacity so that all cells will share the load equally. This is done by individual cell charging and discharging. If this step is not completed, it is possible that some cells will carry most of the load and overheat, presenting a potentially dangerous safety issue. A multi-channel system like the NH Research 9200 series is invaluable.

There are three basic flavors of the NH Research 9200 system testers, each with a specified DC Voltage (40V, 120V or 600V) and Current rating. Additional modules can be inserted into the test rack to increase the number of channels (from 3, up to 12 bi-directional channels for charging and discharging). Current is also expandable, as well as total power, starting from 12kW up to a whopping 252kW if required. Further, modules can be mixed and matched within the same test rack mainframe. The system is programmable via a built-in touch-panel interface or an external PC.

The NHR 9200 series Regenerative Battery Test Systems enables dynamic testing with the capability to perform microsecond-speed changes in current, voltage, and other test conditions to mimic real-world operating conditions. The same capabilities allow it to function as a battery emulator as well, to use in place of batteries when testing an electronic device. It can also be used as a test source for power supply burn-in testing.

Axiom Test Equipment is proud to offer short-term and longer-term rental of the NH Research 9200 series systems to help support your battery test requirements. Additional information and datasheets can be found on our website: NH Research 9200 Regenerative Battery Test Systems available from Axiom Test Equipment. For more Power Testing Equipment resources and equipment used, visit our Power Testing Equipment category page.