400 Mercury Hearing Aid Battery
The No. 400 1.4 volt mercury hearing aid battery was used in some
BTE hearing aids between 1955 and 1961, although the odd hearing aid
still used this battery until 1970.
The No. 400 mercury battery weighed less than a gram, and measured
0.135"
thick
by 0.455" in diameter.
Note: the rare No. 575 battery could also be substituted for the No.
400. It was the same diameter, but 0.003" thinner. The No. 575 battery
was only used in hearing aids between 1961 and 1967. |
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