Battery Discharge Time Estimation for High-Rate Thermal Limits
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Solution Overview
Problem
Existing battery management systems (BMS) struggle to accurately estimate battery discharge time during high-rate discharging, as discharge rates exceeding battery capacity can lead to inaccurate predictions and safety issues due to thermal limitations being reached before chemical capacity is depleted, resulting in inadequate discharge duration estimates in minutes.
Innovation Solution
The system calculates both current-based and temperature-based discharge termination times in seconds, comparing them to determine the actual discharge time duration, accounting for ambient and internal temperature changes, and provides a State Of Health (SOH) prediction based on temperature rise ratios, identifying the end of service life when actual discharge time is less than the minimum predicted time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-rate battery discharging is performed to meet power demands, then power delivery capability is improved, but discharge time estimation accuracy deteriorates due to thermal limitations being reached before chemical capacity depletion
Solution Approach 1:
The patent segments the discharge time estimation into two separate calculations: a current-based time to empty (TTE) calculation that considers chemical capacity depletion, and a temperature-based TTE calculation that considers thermal limitations. By dividing the estimation into these two independent segments, the system can accurately predict discharge duration under high-rate conditions where thermal constraints dominate, while maintaining the ability to calculate based on chemical capacity when it is the limiting factor.
Solution Approach 2:
The patent changes the parameters used for TTE estimation by introducing temperature as a critical parameter alongside current. The system dynamically adjusts the estimation approach based on operating conditions, using temperature-based TTE when thermal limitations are reached and current-based TTE when chemical capacity is the primary constraint. This parameter change enables accurate estimation across the full range of discharge rates.
2Adaptability or versatility
If discharge duration is calculated in minutes according to SBS specification, then compatibility with standard BMS systems is improved, but usability for high-rate applications deteriorates due to insufficient temporal granularity
Solution Approach 1:
The patent implements a dynamic time unit selection mechanism that automatically adapts the display unit (seconds or minutes) based on the calculated discharge duration. When the TTE is less than 60 seconds, the system displays the value in seconds with appropriate labeling; when it exceeds 60 seconds, it converts to minutes. This dynamic adaptation maintains SBS specification compatibility while providing appropriately granular information for high-rate applications.
Solution Approach 2:
The patent adds a temporal dimension to the output by introducing a time unit indicator that specifies whether the discharge duration is expressed in seconds or minutes. This additional dimensional information allows the same numerical value to convey different levels of temporal precision depending on the operating context, resolving the conflict between standard compliance and application-specific usability.
3Reliability
If thermal safety features are implemented to prevent catastrophic failure, then battery safety is improved, but discharge time estimation accuracy deteriorates due to early discharge termination at thermal limits
Solution Approach 1:
The patent performs a preliminary temperature-based TTE calculation before actual discharge occurs, predicting how long the battery will last based on current temperature and thermal characteristics. This preliminary action allows the system to account for thermal safety termination in advance, providing accurate discharge time estimates that reflect when thermal limits will be reached, rather than when chemical capacity is depleted.
Solution Approach 2:
The system continuously monitors actual temperature during discharge and compares it against the predicted temperature trajectory. This feedback mechanism allows the system to update the discharge time estimation in real-time, ensuring accuracy even as thermal conditions evolve. The feedback loop reconciles the thermal safety constraints with the discharge time prediction, maintaining accuracy throughout the discharge process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides accurate, real-time discharge time estimates in seconds, accounting for thermal limitations, ensuring safety and reliability in high-rate discharge applications by continuously compensating for temperature changes, and predicting battery service life effectively.
Implementation Method 1
At such discharge rates, these applications will can potentially discharge the battery in a time period as short as 3 to 5 minutes. Such rapid discharging creates an extreme amount of heat.
Data Source
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AI summary
Embodiments of the disclosure provide systems and methods for estimating battery discharge time duration during high-rate battery discharging. Generally speaking, embodiments of the present disclosure are directed to a prediction of battery run times for short duration, high-current discharge events that are scaled in seconds rather than minutes, and which are continuously compensated for ambient temperature which can alter discharge times as a result of reaching thermal limitations before chemical capacity has actually been exhausted.