Lithium-ion batteries are common batteries in electric and hybrid vehicles. During their lifetime, the batteries will be subjected to vibrations; therefore, vibration testing is demanded by several standards. These standards differ when it comes to frequency range, acceleration levels, etc. From a vibration testing perspective, a battery pack is a complex object built as a large construction containing many small electric compounds. Therefore, the standards might vary depending on the objective of the test. Vibration measurements have been carried out in electric and gasoline vehicles during driving. These measurements are compared with the test severities proposed by the standards. It is found that the vibration test should be performed in three directions, and must contain a wide frequency content well above 200 Hz performed during one test or divided into two separate tests. This is not consistent with many of the existing standards today.
Li-ion batteries are the most popular type of batteries in electric, EV, and hybrid vehicles, HV. During their life time the batteries will be subjected to vibrations and therefore vibration testing is demanded by several standards. Testing on different size levels of the batteries, i.e. cell, module or pack, are proposed. Depending on the standard random vibration tests or tests with sinusoidal excitation are required. To compare these standards with the measurements, Fatigue Damage Spectrum, FDS, and Shock Response Spectrum, SRS, have been used. The FDS is a tool to analyze and compare different types of vibration tests and vibration measurements with respect to the fatigue damage that the vibration will cause on a mechanic structure. The SRS is used to estimate the risk for functional disturbances in electric equipment subjected to shock and vibrations. The comparison shows that the FDS and SRS for different vibration tests proposed for li-ion batteries vary strongly. Both levels and frequency ranges differ. One of the compared standards prescribes testing only in the vertical direction. The measurement done in this study was done during rather hard driving on a test track, this means high but not unrealistic measured acceleration responses. For one of the measured responses, the risk for fatigue during service could be higher than the risk at the tests. The low frequency content of a test can be important as the measurements show higher low frequency content than in many of the standardized tests. But even the high frequency content of the test must be considered as batteries normally are equipped with a large number of small electrical devices with high critical frequencies. Only one of the standards requires a separate test of such devices.
Surface insulation resistance (SIR) measurements have become necessary to perform, especially due to the introduction of lead free solders. It has been reported that SIR and other test methods have to be used for evaluating the reliability of printed wiring boards. This paper presents an investigation on how the SIR test environment influences the test results. The factors varied were temperature and humidity. The temperature was varied between 40 and 85°C, and the relative humidity was varied between 60 and 85%. Furthermore, the influence of different types of process chemicals on SIR was evaluated. Seven lead free solder pastes, of which five were no-clean and two were water soluble, were compared. The influence of using conformal coating was also studied. These solder pastes were used to verify the developed method. A proper test method for SIR measurements is suggested in the paper, as well as a recommendation for use of conformal coating.
This paper discusses how anodic pulses and periodic current reversion influence electrodeposition. Depending on the involved metal and electrolyte, very different effects can be observed and taken advantage of. The Wagner number, Wa, describing the current distribution is shown to be useful for predicting the throwing power at low frequencies of current reversion, even in complex electrochemical systems, but is less useful at higher frequencies. Passivation can occur due to oxide formation, super-saturation of metal salts or depletion of complexing agents at the electrode surface. Furthermore, dissolution and desorption processes in the anodic period can have strong influence on the succeeding cathodic electrocrystallisation affecting preferred crystal orientation, intrinsic stress and current efficiency. A literature survey is combined with experiments from silver plating from a cyanide bath.
Ti2AlC coatings have been fabricated by cold-spray deposition. The microstructure evolution as a function of basic spray parameters temperature and pressure onto AA6060 aluminium alloy and 1.0037 steel substrates has been studied. Adherent and dense 50–80 μm thick Ti2AlC coatings were deposited on soft AA6060 substrates under gas temperature and pressure of 600 °C and 3.4 MPa, respectively, whilst comparable results were obtained on harder 1.0037 steel by using higher temperature (800 °C) and pressure (3.9 MPa).