Multi-Battery Charge Control for Longer Runtime in Lawn Tractors

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Solution Overview

Problem

The inefficiencies in battery management for gardening and agriculture tools and vehicles, particularly due to the limitations of early battery technologies like lead-acid and zinc-carbon batteries, which resulted in short battery life, frequent replacements, and the need for multiple types of batteries and chargers, making them inconvenient and less efficient compared to endothermic engines.

Innovation Solution

A method and device for optimizing battery charging and discharging processes in tools and vehicles, using a control unit to selectively charge and supply power from multiple batteries, allowing for simultaneous power transfer, adaptive charging, and diagnostic monitoring, while reducing the number of battery and charger types needed, and enabling ergonomic battery management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple types of batteries are used for different applications, then the battery life and charging capacity are improved, but the device complexity and number of battery types increase

Engineering Contradiction:
Improvebattery lifeVSAvoidnumber of battery types
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal battery management system that can manage multiple battery types (lead-acid, Ni-Mh, Lithium) through a single control unit. The control unit automatically detects battery type and adjusts charging parameters accordingly, eliminating the need for multiple dedicated chargers and reducing system complexity while maintaining optimal performance for each battery type

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adjusts charging parameters (current, voltage, temperature limits) based on the detected battery type and state of charge. This allows a single charger to optimally charge different battery chemistries by changing its operating parameters, resolving the contradiction between handling multiple battery types and maintaining simple device architecture

Inventive Principle:
Principle #35Parameter changes

2Duration of action of moving object

If high capacity batteries are used, then the duration of action is improved, but the weight and volume increase

Engineering Contradiction:
Improvebattery operation durationVSAvoidbattery weight
Core Design Contradiction:
Duration of action of moving objectVSWeight of moving object

Solution Approach 1:

The patent employs multiple smaller battery units (typically 3-4 individual batteries) that can be independently managed and charged. This segmentation allows the system to achieve the required total capacity and operation duration while distributing the weight and volume across multiple smaller components, improving ergonomics and allowing flexible configuration based on power tool requirements

Inventive Principle:
Principle #1Segmentation

3Loss of time

If fast charging is implemented, then the charging time is reduced, but the thermal effects and energy dissipation increase

Engineering Contradiction:
Improvecharging timeVSAvoidenergy dissipation
Core Design Contradiction:
Loss of timeVSLoss of energy

Solution Approach 1:

The charging system implements periodic charging cycles with variable current intensity. During fast charging phases, the system monitors temperature and state of charge, then transitions to lower current phases when thresholds are approached. This periodic modulation of charging current reduces thermal effects and energy dissipation while maintaining overall fast charging capability

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The control unit continuously monitors battery parameters (voltage, current, temperature) during charging and provides feedback to adjust charging parameters in real-time. When temperature or voltage thresholds are approached during fast charging, the system automatically reduces current to prevent excessive energy dissipation and thermal damage, then resumes higher current when conditions permit

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 solution enhances battery life, reduces energy dissipation, and increases thermal efficiency, allowing for convenient and stable operations with fewer battery and charger types, improving the overall efficiency of battery-powered gardening and agriculture tools and vehicles.

Implementation Method 1

A method and device for optimizing battery charging and discharging processes in tools and vehicles, using a control unit to selectively charge and supply power from multiple batteries

Methodology Applied
Scientific EffectElectrical energy transfer: Conduction (electrical)

Data Source

PatentEP4234317A1Method of managing charge and discharge of a plurality of batteries and lawnmower tractor including a control unit configured for managing charge and discharge of a plurality of batteries
Publication Date: 2023.08.30 STIGA S P A IN BREVE ANCHE ST SPA
  • EP4234317A1 patent drawingFigure 1
  • EP4234317A1 patent drawingFigure 2
  • EP4234317A1 patent drawingFigure 3~4

AI summary

The object of the present invention is a management method for charging and discharging a plurality of batteries (B1-B4) housed in a tool or vehicle (100). The method comprises a selection step, wherein a first part (B1) of the plurality of batteries (B1-B4) is selected. The method comprises a charging step, wherein the first part (B1) of the plurality of batteries (B1-B4) is selectively charged. The method comprises at least one further selection step, wherein a further part (B2, B3, B4) of the plurality of batteries (B1-B4) is selected. The method comprises at least one further charging step, wherein the further part (B2, B3, B4) of the plurality of batteries (B1-B4) is selectively charged. The method comprises a power supply step, wherein at least one power user (101, 102) of the tool or vehicle (100) is powered by a transfer of electrical energy to the power user (101, 102), the transfer of electrical energy occurring simultaneously from the first part (B1) of the plurality of batteries (B1-B4) and the further part (B2, B3, B4) of the plurality of batteries (B1-B4). The present invention further relates to a lawnmower tractor with a plurality of batteries (B1-B4) and a control unit configured for managing the charging and discharging of the plurality of batteries (B1-B4).