520 Mercury Hearing Aid Battery
This No. 520 1.4 volt mercury hearing aid battery by an unknown
manufacturer was used in transistor hearing aids in the
mid-1950s.
The No. 520 mercury battery weighed about 0.03 oz (~1 g), and measured
½" in diameter by ¼" thick (1.2 x 0.7 cm). |
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Top view of the No. 520 mercury battery showing the model number
(520) and some patent information.
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Bottom view of the No. 520 mercury battery. This was one
weird-shaped battery. The bottom was hollow.
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Side view of the No. 520 mercury battery.
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