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Title: Method and apparatus for measuring the state of charge in a battery based on volume of battery components

The state of charge of electrochemical batteries of different kinds is determined by measuring the incremental change in the total volume of the reactive masses in the battery. The invention is based on the principle that all electrochemical batteries, either primary or secondary (rechargeable), produce electricity through a chemical reaction with at least one electrode, and the chemical reactions produce certain changes in the composition and density of the electrode. The reactive masses of the electrodes, the electrolyte, and any separator or spacers are usually contained inside a battery casing of a certain volume. As the battery is used, or recharged, the specific volume of at least one of the electrode masses will change and, since the masses of the materials do not change considerably, the total volume occupied by at least one of the electrodes will change. These volume changes may be measured in many different ways and related to the state of charge in the battery. In one embodiment, the volume change can be measured by monitoring the small changes in one of the principal dimensions of the battery casing as it expands or shrinks to accommodate the combined volumes of its components.
Inventors:
 [1]
  1. (Idaho Falls, ID)
Issue Date:
OSTI Identifier:
870649
Assignee:
Lockheed Idaho Technologies Company (Idaho Falls, ID) ANL
Patent Number(s):
US 5567541
Application Number:
08/407,570
Contract Number:
AC07-94ID13223
Research Org:
Lockheed Martin Idaho Tech Co
Country of Publication:
United States
Language:
English
Subject:
method; apparatus; measuring; charge; battery; based; volume; components; electrochemical; batteries; kinds; determined; incremental; change; total; reactive; masses; principle; primary; secondary; rechargeable; produce; electricity; chemical; reaction; electrode; reactions; changes; composition; density; electrodes; electrolyte; separator; spacers; contained; inside; casing; recharged; specific; materials; considerably; occupied; measured; related; embodiment; monitoring; principal; dimensions; expands; shrinks; accommodate; combined; volumes; battery components; total volume; chemical reaction; chemical reactions; electrochemical batteries; contained inside; /429/