Hugh Hetherington Hearing Aid Museum
Hugh Hetherington Hearing Aid Museum

The Hearing Aid Museum

Hearing Aids of all types—Ear Trumpets, Carbon Hearing Aids, Vacuum Tube Hearing Aids, Transistor Hearing Aids, Body Hearing Aids, Eyeglass Hearing Aids and much more!

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Click on the "General Information" button (top button above) for an overview and general information on this category of hearing aid.

 

Hearing Aid Batteries

Panasonic No. 401PM (Size "N") Mercury Hearing Aid Battery

The Panasonic No. 401PM 1.4 volt size "N" mercury battery was made by Matsushita Electric Industrial Co Ltd of Osaka, Japan around 1970 or thereabouts.

The Panasonic 401PM battery weighed 0.3 oz. (8 g). It measured 1 3/16" high by 7/16" in diameter (2.9 x 1.1 cm).

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Front view of the Panasonic No. 401PM battery showing the model number—401PM.

"N"-sized (401) batteries were commonly used in transistor body aids in the 1950s and 1960s.

They are still used for some assistive listening devices today.

 

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Side view of the Panasonic No. 401PM battery showing warning.

 


 

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Another side view of the Panasonic No. 401PM battery showing the model number—401PM,voltage—1.4 volts, and the polarity—+ at top.
 


 

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Top view of the Panasonic No. 401PM hearing aid battery showing the positive terminal.

 


 

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Bottom view of the Panasonic No. 401PM hearing aid battery showing the negative terminal.

 


 

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Front view of the Panasonic No. 401PM hearing aid 2-battery plastic blister pak.

 


 

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Rear view of the Panasonic No. 401PM hearing aid 2-battery plastic blister pak.

 

 


 

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