Battery Pack Charging Current Derating by Cell Temperature

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Solution Overview

Problem

Battery packs are prone to over-temperature conditions during charging, which can lead to safety risks, reduced battery life, and prolonged charging times due to the need to halt charging when temperature limits are exceeded.

Innovation Solution

A battery controller monitors cell temperature and adjusts the maximum charging current based on an inverse functional relationship with temperature, reducing current as the temperature rises to prevent over-temperature conditions, and halts charging if the upper threshold is exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high charging current is used to charge battery cells, then charging speed is improved, but temperature increases leading to over-temperature conditions

Engineering Contradiction:

Improvecharging speedVSAvoidbattery cell temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The charging current is made dynamic rather than constant. The controller continuously monitors battery cell temperature and adjusts the charging current in real-time based on temperature conditions. When temperature is within acceptable range, higher current is applied for fast charging; when temperature approaches thresholds, current is reduced or charging is paused, preventing over-temperature while maximizing charging speed during safe operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The charging parameters (current, voltage, power) are changed based on temperature feedback. The system transitions between different charging stages and parameter sets depending on the battery's thermal state, enabling optimized charging performance across varying temperature conditions while preventing thermal runaway

Inventive Principle:

Principle #35Parameter changes

2Reliability

If charging is halted when temperature limits are exceeded, then safety is improved, but charging time increases

Engineering Contradiction:

Improvebattery safetyVSAvoidcharging time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system takes preliminary action by continuously monitoring temperature and proactively reducing charging current or pausing charging before the temperature reaches dangerous thresholds. This preventive approach avoids the need for complete charging halts and subsequent cooling periods, maintaining safety while minimizing charging time losses

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A closed-loop feedback system continuously monitors battery temperature and adjusts charging parameters in real-time. The controller receives temperature feedback from sensors and dynamically modifies charging current to maintain temperature within safe operating limits, preventing over-temperature conditions while optimizing charging efficiency and reducing overall charging time

Inventive Principle:

Principle #23Feedback

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 reduces the likelihood of over-temperature conditions, maintains battery life, and minimizes charging interruptions, thereby enhancing safety and efficiency.

Implementation Method 1

at least one temperature sensor configured to obtain a temperature measurement indicative of a temperature of at least cell of the one or more cells

Methodology Applied

Scientific EffectTemperature sensing:

Implementation Method 2

reducing the maximum charging current comprises reducing the maximum charging current based at least in part on an inverse functional relationship between the temperature measurement and the maximum charging current

Methodology Applied

Scientific EffectInverse functional relationship between temperature and current:

Data Source

PatentUS12463437B2Battery pack with temperature limited current

Publication Date: 2025.11.04 TECHTRONIC CORDLESS GP

AI summary

A battery pack can include one or more cells. The battery pack can include at least one temperature sensor configured to obtain a temperature measurement indicative of a temperature of at least cell of the one or more cells. The battery pack can include a controller, the controller configured to be placed in signal communication with a battery charger. The controller can be configured to perform operations. The operations can include obtaining the temperature measurement from the at least one temperature sensor. The operations can include determining, based at least in part on the temperature measurement, that the temperature of the at least one cell is between a lower temperature threshold and an upper temperature threshold. The operations can include, in response to determining that the temperature of the at least one cell is between the lower temperature threshold and the upper temperature threshold, reducing a maximum charging current, wherein reducing the maximum charging current comprises reducing the maximum charging current based at least in part on an inverse functional relationship between the temperature measurement and the maximum charging current. The operations can include controlling the battery charger based at least in part on the maximum charging current to charge the one or more cells.