State of charge

About: State of charge is a research topic. Over the lifetime, 12013 publications have been published within this topic receiving 201419 citations. The topic is also known as: SoC & SOC.

Self-reactive rating of thermal runaway hazards on 18650 lithium-ion batteries

Abstract: Vent sizing package 2 (VSP2) was used to measure the thermal hazard and runaway characteristics of 18650 lithium-ion batteries, which were manufactured by Sanyo Electric Co., Ltd. Runaway reaction behaviors of these batteries were obtained: 50% state of charge (SOC), and 100% SOC. The tests evaluated the thermal hazard characteristics, such as initial exothermic temperature (T 0), self-heating rate (dT dt −1), pressure-rise rate (dP dt −1), pressure temperature profiles, maximum temperature, and pressure which were observed by adiabatic calorimetric methodology via VSP2 using customized test cells. The safety assessment of lithium-ion cells proved to be an important subject. The maximum self-heating rate (dT dt −1)max and the largest pressure-rise rate (dP dt −1)max of Sanyo 18650 lithium-ion battery of 100% SOC were measured to be 37,468.8 °C min−1 and 10,845.6 psi min−1, respectively, and the maximum temperature was 733.1 °C. Therefore, a runaway reaction is extremely serious when a lithium-ion battery is exothermic at 100% SOC. This result also demonstrated that the thermal VSP2 is an alternative method of thermal hazard assessment for battery safety research. Finally, self-reactive ratings on thermal hazards of 18650 lithium-ion batteries were studied and elucidated to a deeper extent.

SOC Estimation of Lithium-Ion Battery Pack Considering Balancing Current

Abstract: The state-of-charge (SOC) estimation approaches based on the pack model can hardly provide precise estimation due to cell difference, while the approaches based on each cell cost high computation resource, which are not suitable for real-time application. The estimation error can be further enlarged without considering balancing current. The SOC estimation approach of the battery pack considering balancing current is proposed, which dynamically searches for the cell with maximum or minimum voltage, and it only needs to calculate the selected cell in every estimation cycle. Compared to the approaches based on the pack model or each single cell, this approach can achieve precise pack SOC and cost less calculation time and resource. It has been verified with ten series-connected 200 Ah Li(NiCoMn)O2 batteries. The SOC estimation error is limited to 0.3% during the charging process, and a reduction of 2.5% is achieved compared to an error of 2.8% based on the pack model. A reduction of 1% is achieved compared to an error of 1.5% based on the pack model during the discharging process. Compared to an error of 1.7% without considering balancing current, a reduction of 1.4% is achieved during the charging process.

Battery state of charge metering method and apparatus

Abstract: The system includes a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge. A switching circuit is provided for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in the integrator to provide a time based resultant indication of the stored binary digital value. A filtering means is included to provide a substantially smooth analog output voltage having an amplitude corresponding to the summation of the pulses. The system preferably includes a delayed high voltage reset feature to set the integrator to a full charge state in response to voltage levels accompanying charging of the battery.