3867681 is referenced by 20 patents and cites 2 patents.

Batteries in locations such as unattended telephone buildings are kept in a good and reliable condition by a circuit which provides a normal charge periodically, which provides a normal charge each time the primary electrical power fails and is restored, and which provides an equalizing charge for a predetermined length of time in response to a manual or automatic operation.

Title
Battery charging circuit
Application Number
05/452,804
Publication Number
3867681
Application Date
March 20, 1974
Publication Date
February 18, 1975
Inventor
Smith William R
Bishop Larry D
Assignee
General Electric Company
IPC
H02j 07/04
H04M 19/06
H04M 19/00
H02J 07/00
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