Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf

Myall, Daniel J.; Ivanov, Dima; Larason, Walter; Nixon, Mark W.; Møller, Henrik Bjarne

doi:10.20944/preprints201803.0122.v1

Cited by 12 publications

(11 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As it can be seen in the figure, capacity decreases with a linear trend in the initial stages of aging, which is consistent with the FL evolution reported from real Nissan Leaf data [37]. Note that the operating conditions in EVs and in the SL test of this contribution are different, and therefore the slopes of the linear stage could vary.…”

Section: A Capacity Evolutionsupporting

confidence: 89%

Experimental Assessment of First- and Second-Life Electric Vehicle Batteries: Performance, Capacity Dispersion, and Aging

Braco

Martín

Berrueta

et al. 2021

IEEE Trans. on Ind. Applicat.

View full text Add to dashboard Cite

Nowadays, the reuse of electric vehicle batteries is considered to be a feasible alternative to recycling, as it allows to benefit from their remaining energy capacity and to enlarge their lifetime. Stationary applications, such as self-consumption or off-grid systems support, are examples of second-life (SL) uses for retired batteries. However, reused modules that compose these batteries have heterogeneous properties, which limit their performance. This paper aims to assess the influence of degradation in modules from electric vehicles, covering three main aspects: performance, capacity dispersion and extended SL behavior. Firstly, a complete characterization of new and reused modules is carried out, considering three temperatures and three discharge rates. On a second stage, intra-and inter-module capacity dispersion is evaluated with new and reused samples. Finally, the behavior during SL is also analyzed, through an accelerated cycling test so that the evolution of capacity and dispersion are assessed. Experimental results show that the performance of reused modules is specially undermined at low temperatures and high current rates, as well as in advanced stages of aging. The intra-module dispersion is found to be similar in reused and new samples, while the inter-module differences are nearly four times greater in SL.

show abstract

Section: A Capacity Evolutionsupporting

confidence: 89%

Experimental Assessment of First- and Second-Life Electric Vehicle Batteries: Performance, Capacity Dispersion, and Aging

Braco

Martín

Berrueta

et al. 2021

IEEE Trans. on Ind. Applicat.

View full text Add to dashboard Cite

show abstract

“…The nominal voltage of a single cell was 3.7 V, and nominal voltage of the battery pack was 355.2 V. The power demand per second of a single cell was calculated. The energy available from the battery pack at the nominal pack voltage was 28.4 kWh, comparable to a real BEV [39].…”

Section: Legislative Drive Cycle Analysismentioning

confidence: 91%

A New Consideration for Validating Battery Performance at Low Ambient Temperatures

2018

View full text Add to dashboard Cite

Existing validation methods for equivalent circuit models (ECMs) do not capture the effects of operating lithium-ion cells over legislative drive cycles at low ambient temperatures. Unrealistic validation of an ECM may often lead to reduced accuracy in electric vehicle range estimation. In this study, current and power are used to illustrate the different approaches for validating ECMs when operating at low ambient temperatures (−15 • C to 25 • C). It was found that employing a current-based approach leads to under-testing of the performance of lithium-ion cells for various legislative drive cycles (NEDC; FTP75; US06; WLTP-3) compared to the actual vehicle. In terms of energy demands, this can be as much as~21% for more aggressive drive cycles but even~15% for more conservative drive cycles. In terms of peak power demands, this can range from~27% for more conservative drive cycles to~35% for more aggressive drive cycles. The research findings reported in this paper suggest that it is better to use a power-based approach (with dynamic voltage) rather than a current-based approach (with fixed voltage) to characterise and model the performance of lithium-ion cells for automotive applications, especially at low ambient temperatures. This evidence should help rationalize the approaches in a model-based design process leading to potential improvements in real-world applications for lithium-ion cells.

show abstract

“…To scale it to cell level, the battery pack considered, had 48 modules and each module had four cells connected in a 2P2S configuration [9]. From Table 2, the nominal voltage of a single cell was 3.7 V. Thus, the nominal pack voltage was 355.2 V. Therefore, the pack capacity was 80 Ah, and the pack energy was 28.4 kWh, making it comparable to a real BEV [42]. This was used to calculate the power demand at which the cells were cycled.…”

Section: Modelling Methodologymentioning

confidence: 99%

Improving Accessible Capacity Tracking at Low Ambient Temperatures for Range Estimation of Battery Electric Vehicles

2020

View full text Add to dashboard Cite

Today’s market leading electric vehicles, driven on typical UK motorways, have real-world range estimation inaccuracy of up to 27%, at around 10 °C outside temperature. The inaccuracy worsens for city driving or lower outside temperature. The reliability of range estimation largely depends on the accuracy of the battery’s underlying state estimators, e.g., state-of-charge and state-of-energy. This is affected by accuracy of the models embedded in the battery management system. The performance of these models fundamentally depends on experimentally obtained parameterisation and validation data. These experiments are mostly performed within thermal chambers, which maintain pre-set temperatures using forced air convection. Although these setups claim to maintain isothermal test conditions, they rarely do so. In this paper, we show that this is potentially the root-cause for deterioration of range estimation at low temperatures. This is because, while such setups produce results comparable to isothermal conditions at higher temperatures (25 °C), they fail to achieve isothermal conditions at sub-zero temperatures. Employing an immersed oil-cooled experimental setup, which can create close-to isothermal conditions, we show battery state estimation can be improved by reducing error from 49.3% to 11.7% at −15 °C. These findings provide a way forward towards improving range estimation in cold weather conditions.

show abstract

Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf

Cited by 12 publications

References 4 publications

Experimental Assessment of First- and Second-Life Electric Vehicle Batteries: Performance, Capacity Dispersion, and Aging

Experimental Assessment of First- and Second-Life Electric Vehicle Batteries: Performance, Capacity Dispersion, and Aging

A New Consideration for Validating Battery Performance at Low Ambient Temperatures

Improving Accessible Capacity Tracking at Low Ambient Temperatures for Range Estimation of Battery Electric Vehicles

Contact Info

Product

Resources

About