Antedating of "flat (battery)"

[Hugo]

"flat" as applied to an electric battery (OED sense 9c: 1951)

I found three 1941 antedatings in Starters and Generators (Edward Molloy, ‎Ernest Walter Knott), visible in full view at Hathitrust: http://catalog.hathitrust.org/Record/001040347

Page 85:

[Begin]
If the clutch is not slipping, the trouble may be insufficient volts reaching the motor, due to a flat battery or a bad connection or switch introducing resistance in the circuit, an electrical fault in the starter, or, very rarely, a mechanical fault in the starter.
[End]

http://babel.hathitrust.org/cgi/pt?id=mdp.39015020940089;view=1up;seq=97

Page 86:

[Begin]
A flat battery should be replaced, but the reason for the battery being discharged should be investigated.
[End]

http://babel.hathitrust.org/cgi/pt?q1=%22flat%20battery%22;id=mdp.39015020940089;view=1up;seq=98;start=1;size=10;page=search;num=86

Page 98:

[Begin]
Under this no-gap condition, the plunger will remain home on a very reduced voltage (which may occur with a flat battery) and will be less susceptible to vibration, and the contact pressure is a fixed and known amount, being the force of the spring (11), and does not vary with voltage.
[End]

http://babel.hathitrust.org/cgi/pt?q1=%22flat%20battery%22;id=mdp.39015020940089;view=1up;seq=110;start=1;size=10;page=search;num=98

Hugo

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