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www.us-tech.com
September, 2021
Battery Test and Inspection is Critical to EV Performance
By Chris Davies, Product Manager — Bond Test, and Daniel Topan, Product Manager, Nordson Test & Inspection T
he automotive sector is booming with electric vehicles. In 2020, three million electric vehicles (EVs) were sold world-
wide. Rapid development of battery technolo- gy is leading to better real-world ranges and is shifting consumer opinion. Europe is leading the way with
Bloomberg reporting that 11 percent of all new car sales were EVs, rising now to 15 per- cent throughout 2021. Primarily the adop- tion has been due to the reduced running costs.
Thermal Management Powertrain reliability in EVs depends on
overcoming the technical challenges around battery lifetime and thermal management of the interconnects in the power delivery sys- tems. Significant development has gone into effective cooling of the inverters, battery cells and ensuring that range and power don’t di- minish over the 10-year typical vehicle life- time. The batteries are now energy-dense with high powered connections that must be as reliable as the fuel system in a convention- al combustion engine. This poses a quality control challenge re-
quiring 100 percent inspection and batch testing of the battery pack to guarantee re- peated charge and discharge with high cur-
rents over time. A low resistance and well- bonded cell are critical to guarantee a long powertrain lifetime. EV batteries are characterized in a cou-
ple of ways. In the first method, cell connec- tions are tested to destruction in a batch
Destructive Bondtesting Interconnect type varies by manufactur-
er ranging from ultrasonic wirebonds, laser- welded tabs, or capacitive-welded busbars. These are best characterized using an inde- pendent force measurement to quantify the adhesion. The physically bonded area (as opposed
to the contact area) is the source of weakness for high-power connections and hence de- structive test force can be used for quality control. Destructive testing of the cell to busbar
bond is performed in batches, coupons, or on the entire battery pack. Typically, a peel, shear or pull test is used to measure the force required to separate the busbar from each cell. Nordson Test & Inspection bondtesters
Battery packs in EVs must be safe and reliable.
process or during new product development to characterize the bonding process. Another way is through nondestructive testing of the individual battery cells to make sure that these comply with the specifications and are not damaged.
can measure heavy gauge wire bonds or bat- tery tab welds in any of the three test modes. Typical forces are between 44 and 220 lb (20 and 100 kg) and the high-precision linear en- coder x/y stages deliver exceptional accuracy for the smaller interconnects, allowing auto- matic software test routines to be used.
Nondestructive Cell X-Ray Inspection For nondestructive testing, automated
X-ray inspection (AXI) is used, as it enables Continued on next page
Visit us at booth 2027
Openair-Plasma®
for High Quality Joints and Long-Lasting Batteries
www.plasmatreat.com See at The Battery Show, Booth 2027
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