Battery Tester for People with Physical and Mental Disabilities

Designers: Brandon Stroy and Ravi Baji
Client Coordinators: Lisa Williams, Generations Tadpole Assistive Technology Lending Library
Supervising Professor: Dr. Larry N. Bohs

The Generations Tadpole Lending Library provides people with physical and mental disabilities low-tech assistive technology devices and toys. Many of these products use batteries, which must be tested regularly. Because Tadpole employs people with various disabilities, they need an easily manipulated battery tester with obvious, multi-sensory indicators. A device was built to make testing batteries simpler and more interactive. It features simple operation, as well as visual, auditory, and vibratory indications of a good or a bad battery. The device allows  more employees to test batteries, improving their salary and independence.

Employees at Tadpole receive a salary based upon the type and number of jobs they can accomplish. If an employee learns to do a new task, they increase their salary. Lisa Williams, the Director at Tadpole, had this to say about the Battery Tester: “The employees at Generations-Tadpole have been using it daily. The employees are responding well to the variety of feedback that the battery tester offers. We have been able to allow 5 more employees to expand their job responsibilities to include testing batteries! This has increased their participation in the program as well as their salary. We have a young lady with a visual impairment and a hearing impairment who is now able to test batteries independently.

The battery tester (Figure 1) consists of a mechanical testing unit, a circuitry unit, and three peripheral response units. The testing unit allows all standard types of cylindrical batteries to be tested between two copper plates in the front of the device. The top plate is angled downwards, and held in position with a spring and hinges. Batteries are held vertically and inserted by sliding them to the back of the tapered testing unit. When the battery is pushed in completely, a rear pushbutton switch is contacted, signaling the circuitry to test. Two parallel copper strips on the top of the box test 9V batteries. One of the strips is spring loaded, with a contact pushbutton to signal battery insertion. The circuitry unit includes four input optoisolators, which allow batteries to be inserted in either polarity orientation. When the battery voltage is above a threshold and the battery insertion switch is activated, a “good battery” signal is generated. If the voltage is below the threshold, a “bad battery” signal is created.

Three sensory outputs are available: LED’s (visual), vibration (tactile), and digital voice (auditory). Any combination of outputs may be selected to tailor the device for specific users. Two of the peripheral response units contain LED’s and digital voice circuitry. A good battery signals constant-on LED’s and a message such as “good battery” on one of the response units. A bad battery signals flashing LED’s and a “bad battery” message. The third response unit contains a motor with an offset weight on the shaft to create vibration. A good battery signals constant vibration,    while a bad battery signals pulsating vibration. The visual/auditory response units can be positioned in proximity to battery bins to facilitate sorting of good and bad batteries. Materials for the battery tester cost approximately $500.

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