The core application and technical value of high and low temperature liquid cooling units in power battery testing

1、 Positioning: Power BatteryThe core solution of "precise temperature control"

High and low temperature liquid cooling units pass throughLiquid medium (such as water)-Forced circulation of ethylene glycol solutionRealize high-precision temperature control of battery detection environment（-The temperature control accuracy (± 0.1 ℃), heat exchange efficiency (3-5 times higher than traditional air cooling), and dynamic response speed (temperature change rate can reach 5 ℃/min) of the air temperature control system are significantly better than those of the air temperature control system.

In the testing of power batteries, liquid cooled units areHigh rate charging and discharging, long cycle, multi-channel parallel testingWaiting for the scene'Essential equipment' directly solves the pain points of traditional air-cooled temperature control lag, poor temperature uniformity, and high energy consumption, supporting comprehensive performance verification from battery cells to system levels.

2、 Core application scenarios and technological advantages

Based on the different stages of power battery testing (research and development, production, certification), the application of liquid cooled units can be divided into the following four core scenarios:

1. High rate charge and discharge performance testing: solving the temperature control problem of "transient thermal shock"

lTesting requirementsThe power battery isWhen charging and discharging at high rates such as 3C/5C/10C (such as the 10C fast charging test for 4680 battery cells), the instantaneous heat generation can reach 5-10 times that of conventional operating conditions (single cell heating power ≥ 100W). It is necessary to quickly remove the heat to avoid the risk of capacity decay or thermal runaway caused by local overheating.

lThe core function of liquid cooling unit：

nPrecise Temperature Control: Liquid cooled plate with adjustable flow rate (in conjunction with battery cells)/Control the surface temperature of the battery at 25 ± 2 ℃ (the optimal charging and discharging temperature range), with a temperature difference of ≤ 1 ℃ (to avoid deterioration of cell consistency caused by temperature gradients);

nDynamic thermal response: SupportPulse based cooling/heating, such as instantaneous cooling during the 10C discharge stage (lasting for 30 seconds), quickly returning to room temperature after discharge, simulating the real driving scenario of "rapid acceleration idle" for users.

lTechnical parameter matching：

nCooling capacity:5~50kW (single channel), supporting independent control of multiple channels (such as a 32 channel testing system);

nFlow regulation range:0.5~10L/min (dynamically matched according to heating power to avoid overcooling or undercooling);

nTemperature difference between import and export:≤ 3 ℃ (ensuring heat exchange efficiency and preventing coolant phase transition).

2. Long cycle life testing: ensuring data accuracy under "constant temperature environment"

lTesting requirementsPower battery cycle life test (such as1000/3000 cycles are requiredConstant temperature environmentProceed below (such as25 ℃± 0.5 ℃) to eliminate the interference of temperature fluctuations on the capacity decay rate (battery life may be shortened by 50% for every 10 ℃ increase in temperature).

lThe core function of liquid cooling unit：

nConstant temperature stability: ThroughPID closed-loop control controls the temperature fluctuation inside the test chamber within ± 0.1 ℃ (better than the ± 2 ℃ required by the national standard GB/T 31484), ensuring the repeatability of cyclic data (with testing errors of ≤ 2% for different batches);

nLow energy consumption operation: AdoptingVariable frequency compressor+plate heat exchanger "saves more than 30% energy compared to traditional air-cooled units (especially in long-term continuous operation scenarios, such as 3000 cycles lasting 1-2 months).

lTypical Case：

nA certain car companyThe NCM523 battery cell underwent 1000 cycles of testing (1C charge/1C discharge), and the liquid cooling unit stabilized the ambient temperature at 25 ℃± 0.1 ℃. The final capacity retention rate was 82.3%, and the data dispersion (RSD) was ≤ 1.5%, much lower than the 4.2% of the air-cooled system.

3. Cell sorting and module consistency testing: achieving "batch temperature equalization" and efficiency improvement

lTesting requirementsOn the production line, battery cells need to be sorted by parameters such as capacity, internal resistance, and self discharge rate (such as sorting)A/B/C grade battery cells), and temperature uniformity directly affects the consistency of test results (for every 1 ℃ temperature difference, the capacity test error is about 0.5%).

lThe core function of liquid cooling unit：

nMulti channel parallel temperature control: ForThe 8/16/32 channel cell testing rack provides an independent liquid cooling circuit, with a temperature deviation of ≤ 0.2 ℃ for each channel, ensuring that the same batch (such as 5000 cells) is sorted under the same temperature conditions, resulting in a 50% increase in sorting efficiency (compared to single channel testing);

nQuick temperature change switching: SupportThe seamless connection between "high-temperature aging and room temperature testing" allows the liquid cooling system to reduce the temperature to 25 ℃ within 10 minutes after 24 hours of aging at 45 ℃, and directly conduct capacity testing to shorten the production cycle.

4. System level (battery pack) environmental adaptability testing: simulating thermal management capabilities under "working conditions"

lTesting requirementsThe battery pack needs to pass throughSystem level tests such as "low temperature start", "high temperature endurance", "temperature shock", etc. (such as performance verification in an environment of -40 ℃~55 ℃ as required by the national standard GB/T 31485), the liquid cooling unit needs to be equipped with the built-in battery packVehicle thermal management system（BMS collaborative workVerify its effectiveness in temperature control.

lThe core function of liquid cooling unit：

ntemperature simulation: ThroughThe combination of "compressor refrigeration+electric heating" provides a wide temperature range environment of -40 ℃~85 ℃ for the battery pack, coupled with flow control (0~50L/min), simulating the real working conditions of the vehicle's liquid cooling circuit (such as BMS starting PTC heating at -20 ℃ in winter, the liquid cooling unit needs to provide a low-temperature environment of -20 ℃ synchronously to verify heating efficiency);

nThermal runaway suppression verificationIn the battery pack thermal runaway spread test, the liquid cooling unit can quickly switch toEvaluate the cooling suppression effect of liquid cooling system on thermal runaway cells in the "-40 ℃ rapid cooling mode" (such as reducing the temperature of faulty cells from 200 ℃ to below 80 ℃ within 10 minutes).

3、 Key indicators and technological trends for selection

lCore selection parameters：

a)Temperature control range and accuracy：-40 ℃~150 ℃ (basic version), -60 ℃~200 ℃ (wide temperature version), accuracy ± 0.1 ℃~± 0.5 ℃ (depending on the scenario, research and development scenarios prioritize high accuracy);

a)temperature change rate：0.5~10 ℃/min (dynamic testing requires high speed, such as temperature shock testing requiring 10 ℃/min);

a)compatibility: Support for battery testing system（CTS）、 Data acquisition device (DAQ) linkage, real-time feedback of temperature data and automatic adjustment of flow/power;

a)Environmental Protection and Safety: Adopting lowGWP refrigerants (such as R454C replacing R22) have safety functions such as leak alarm, over temperature protection, and pressure overload shutdown.

ltechnology trends：

nintelligentization: IntegrationAI algorithm predicts the change of heat load through historical data, adjusts the cooling/heating power in advance, and further improves the temperature control accuracy to ± 0.05 ℃;

nmodularization: SupportThe "one to many" architecture (one host with 4-8 test chambers) reduces the equipment cost of multi-channel testing;

nEfficient heat recoveryRecycling waste heat from the testing process (such as heat generated by high rate discharge) for heating other low-temperature testing chambers, with a comprehensive energy efficiency ratio（COP has been raised to 4.0Up there.

summary

High and low temperature liquid cooling units are used for power battery testingThe key equipment for upgrading from "extensive" to "refined" lies in its core valueAccurate temperature control, efficient heat exchange, and long-term stabilityCovering the entire chain of detection requirements from battery cells to system level. Moving towards high energy density (such as solid-state batteries) and high rate (such asUnder the trend of developing fast charging (10C) and long lifespan (such as 1500 cycles),Aoxu ZhaochenLiquid cooled units will further advance towardsThe iteration towards "intelligence, modularity, and low energy consumption" has become the core infrastructure supporting breakthroughs in battery performance and safety assurance.