The new GB/T nationally recommended standards released in 2015, are divided into three topics: performance test standards, life test standards, and safety test standards.
The requirements and testing methods for electric vehicle battery’s life-cycle in GB/T 31484-2015 are to inspect the life-cycle indicator of the battery cell, module, and system. By the standard, the life-cycle test conditions are divided into standard life-cycle and working condition life-cycle, which changes with various vehicle types (passenger/commercial) and driving systems (hybrid/electric).
- Standard life-cycle: The test cycle is composed of standard charge/discharge conditions with cycles up to 500 times (power capacity is not under 90% of initial capacity) or up to 1000 times (power capacity is not under 80% of initial capacity).
- Working condition life-cycle: The test cycle is composed of primary charging and discharging conditions where the cumulative total discharge energy (Wh) must be 500 times of initial energy (Wh).
Taking the driving condition of hybrid passenger vehicle battery as an example, when the battery capacity testing range is SOC80%~SOC30%, the primary charge/discharge current profile conditions are shown in the figures below.
In addition to basic test steps, the Chroma charge and discharge test system has driving profile simulation functions that allow the user to load the battery waveform of a sample driving status. Current or power mode can be selected for simulation to meet the NEDC or FUDS standards. The maximum response time is 10msec, and the fastest DAQ rate is 10msec. Its bi-directional architecture can make sure that the current will not be interrupted during the transition from charge to discharge in order to facilitate that the driving conditions are accurately simulated and in compliance with the GB/T 31484-2015 various requirements for primary charge/discharge driving profiles.
During long-term life-cycle testing, safety issues are very important when testing batteries. Other than preventing over-charging or over-discharging the batteries, it is also recommended to use the BMS (Battery Management System) to monitor the balance and temperature of every cell for protection, as the battery pack could be damaged by overheating when any of the internal cell voltages is either too high or too low. Furthermore, it is suggested to add DCIR testing to every charge and discharge cycle for battery aging inspection. The charge and discharge system provided by Chroma has power regenerative functions that can reduce massive power consumption. It can also make sure the power grid remains stable even in dynamic charge and discharge mode, and has no influences on other equipment from harmonic pollution.
The application of driving profile simulation is shown in the figures below.
To cope with the GB/T standards for battery performance and safety testing, Chroma has offered a battery pack automatic testing solution for battery short circuit, internal resistance, hipot insulation, and dynamic pulse charge/discharge tests. It ensures that the safety performance of the battery production and development meets the GB/T national standards.
With 30 years of experience in test and measurement instrumentation, Chroma is able to provide wide variety of testing solutions for power and storage batteries. These include Regenerative Battery Pack Test Systems for battery cells, battery modules and battery packs, BMS test system, Battery Pack Auto Test System, battery simulators and super capacitors.These solutions are in use worldwide by manufacturers and third party laboratories. For any questions regarding the battery test solution, please provide your contact information and we will reach out to you for further service.