Lithium Starter Battery Solid State Switch

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Solution Overview

Problem

Lead-acid starter batteries for internal combustion engines are heavy, bulky, have short cycle and calendar life, and are inefficient, especially in cold weather, requiring oversized capacity and complex electronic protection circuits that induce heat and electrical losses, and are prone to damage from over-charging and over-discharging.

Innovation Solution

Replacing lead-acid batteries with lithium-based cells, such as lithium iron phosphate, and using a solid state switching configuration with MOSFETs or IGBTs to control current flow, eliminating the need for protection circuitry and allowing for bidirectional current control, preventing over-charging and over-discharging, and providing compact and efficient power management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If lead-acid batteries are used for starter applications, then the battery can provide sufficient current for engine starting, but the battery becomes heavy and bulky requiring oversized capacity

Engineering Contradiction:

Improvestarting currentVSAvoidbattery weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent changes the chemical composition parameter of the battery from lead-acid to lithium-based chemistry, which fundamentally alters the weight-to-power ratio. Lithium batteries provide the same or higher power output with significantly reduced weight and volume, directly resolving the contradiction between providing sufficient starting current and minimizing battery mass.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If electronic protection circuitry is added to prevent over-charging and over-discharging, then battery safety is improved, but heat losses and electrical losses increase

Engineering Contradiction:

Improvebattery protectionVSAvoidheat and electrical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces mechanical/electronic protection circuitry with solid-state switching devices that provide protection through inherent electrical characteristics. The solid state switch uses voltage-dependent conduction to automatically prevent over-charging and over-discharging without requiring separate protection circuits, thereby maintaining reliability while eliminating the energy losses associated with electronic protection components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If relay or contactor is used for current switching, then current flow can be controlled, but continuous current is required to maintain switching state consuming additional energy

Engineering Contradiction:

Improvecurrent controlVSAvoidswitching energy

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The solid state switch is a voltage-operated device that automatically responds to voltage conditions without requiring continuous control current. When the battery voltage exceeds the breakdown voltage, the switch automatically conducts; when voltage drops below the sustaining level, it automatically blocks. This self-service operation eliminates the need for continuous energy input to maintain the switching state, resolving the energy consumption issue.

Inventive Principle:

Principle #25Self-service

4Power

If lead-acid battery is used in cold weather, then engine starting is possible, but internal impedance increases reducing available current

Engineering Contradiction:

Improveavailable currentVSAvoidcold weather performance

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent changes the electrochemical parameters of the battery system by using lithium-based chemistry instead of lead-acid. Lithium batteries maintain lower internal impedance across a wider temperature range, particularly in cold conditions, due to the different electrochemical reactions and ion transport mechanisms. This parameter change enables sufficient current delivery for engine starting in cold weather without the impedance problems that plague lead-acid batteries.

Inventive Principle:

Principle #35Parameter changes

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

The lithium-based battery system reduces weight and size, increases cycle and calendar life, improves efficiency, and provides reliable cold-weather performance with reduced maintenance, while preventing battery damage and extending battery life through controlled charging and discharging.

Implementation Method 1

a solid state switch placed in-line with the battery output power terminals, the solid state switch can be electronically controlled to open or close the current pathway leaving or entering the battery

Methodology Applied

Scientific EffectSolid state switching:

Implementation Method 2

lithium-based cell for starting such engines

Methodology Applied

Scientific EffectElectrochemical energy storage: Battery (electricity)

Data Source

PatentUS9412994B2Lithium starter battery and solid state switch therefor

Publication Date: 2016.08.09 NORRIS VENTURES LLC

AI summary

Apparatus for increasing the efficiency of a starter battery for a starter motor of an internal combustion engine in a battery pack arrangement with one or more lithium based cells. The invention includes a solid state switching configuration for high powered battery systems for protecting against over-charging, over-discharging and short circuiting of batteries, especially starter batteries for internal combustion engines.