Flooded Lead-Acid Battery Separators for Acid Stratification Reduction
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Solution Overview
Problem
Conventional flooded lead-acid batteries in start/stop vehicles experience acid stratification due to partial state of charge, leading to reduced acid mixing, increased internal resistance, and shorter battery life, while VRLA AGM batteries are more expensive and prone to overcharging.
Innovation Solution
The use of optimized separators with specific surface characteristics, such as serrated or dimpled polyolefin membranes, enhances acid mixing and circulation within flooded lead-acid batteries, reducing acid stratification without the need for mechanical acid mixing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional flooded lead-acid batteries operate in partial state of charge (start/stop vehicles), then fuel economy improves through idle start/stop function, but acid stratification occurs leading to reduced battery life
Solution Approach 1:
The patent modifies the physical parameters of the separator by introducing surface features (protrusions, dimples, ribs) with specific geometries, heights, and distributions. These parameter changes create turbulence and mixing effects in the electrolyte during battery operation, preventing acid stratification while maintaining the partial state of charge operating conditions necessary for fuel economy improvement
2Reliability
If VRLA AGM batteries are used to prevent acid stratification, then battery performance improves, but cost increases and overcharging problems occur
Solution Approach 1:
The patent employs a conventional flooded battery separator with added surface features instead of expensive VRLA AGM technology. This approach achieves acid mixing and stratification prevention at lower cost by using geometric features on the separator that induce electrolyte movement, rather than relying on the expensive absorbed glass mat structure of VRLA batteries
Solution Approach 2:
The patent replaces the need for mechanical acid mixing systems or VRLA AGM structures with a passive geometric feature system on the separator. The protrusions and dimples create natural convection and turbulence through electrolyte flow and gas bubble movement, eliminating the need for active mechanical mixing or expensive alternative battery chemistries
3Stability of the object's composition
If gas bubbles are generated in overcharge state, then electrolyte mixing improves, but in partial charge state no gas bubbles are generated leading to acid stratification
Solution Approach 1:
The patent incorporates pre-designed geometric features (protrusions, dimples, ribs) on the separator surface that are prepared in advance to induce electrolyte mixing. These features are structurally built into the separator before battery operation, so they immediately begin creating turbulence and mixing effects as electrolyte flows over them, without requiring gas bubble generation or overcharge conditions to activate the mixing mechanism
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 improved separators significantly reduce acid stratification and enhance battery performance, achieving performance comparable to or exceeding that of VRLA AGM batteries while maintaining the cost-effectiveness of flooded lead-acid batteries.
Implementation Method 1
enhances acid mixing and circulation within flooded lead-acid batteries, reducing acid stratification
Data Source
AI summary
Improved battery separators are disclosed herein for use in flooded lead-acid batteries, and in particular enhanced flooded lead-acid batteries. The improved separators disclosed herein provide for enhanced electrolyte mixing and substantially reduced acid stratification. The improved flooded lead-acid batteries may be advantageously employed in applications in which the battery remains in a partial state of charge, for instance in start/stop vehicle systems. Also, improved lead-acid batteries, such as flooded lead-acid batteries, improved systems that include a lead-acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use may be provided.