across the table to the 800 F. column. This reading in the 800 F. column is the normal specific gravity. This normal figure
must be used to establish the condition of the battery and its available cranking power.
Table IV. Specific Gravity Temperature Corrections
Available crank-
ing power
50%......................
1.277
1.267
1.259
1.255
1.251
1.243
1.236
1.220
1.213
1.209
1.205
58.3%...................
1.287
1.277
1.269
1.265
1.261
1.253
1.246
1.230
1.223
1.219
1.215
66.6%...................
1.297
1.287
1.279
1.275
1.271
1.263
1.256
1.240
1.233
1.229
1.225
75 %.....................
1.307
1.297
1.289
1.285
1.281
1.273
1.266
1.250
1.243
1.239
1.235
83.3%...................
1.317
1.307
1.299
1.295
1.291
1.283
1.276
1.260
1.252
1.248
1.245
91.6%...................
1.327
1.317
1.309
1.305
1.301
1.294
1.286
1.270
1.262
1.258
1.255
100%....................
1.338
1.328
1.320
1.316
1.312
1.304
1.296
1.280
1.272
1.268
1.265
c. Storage. When the charged battery is put in storage, the electrolyte will show a gradual and continuous drop in
specific gravity. This is caused by a slow acid reaction with the active materials, even when there is no closed external
circuit. When the batteries are kept in storage below 800 F., the drop will average about 0.001 per day over a month's
time. The battery must, be recharged every 30 days to keep it ready for service. The recharging rate must equal one
ampere per positive plate per cell.
Note. Do not smoke or permit open flame in the vicinity when recharging batteries.
d. Testing.
(1) Test batteries for specific gravity weekly. If the ambient temperature is extremely high or low, measure the
temperature of the electrolyte first, using a mercury thermometer. Use a standard hydrometer to test each
battery cell and correct the readings by referring to table IV. Determine the battery condition by referring to
table II. Recharge, if necessary, using a standard battery charger. Be sure to observe the polarity of the
battery when charging.
(2) Use a voltmeter to test each cell for terminal voltage. Each fully charged ell must deliver about 2 volts. A
low output voltage may indicate a low charge or internal trouble. Check the specific gravity and charge the
battery if necessary. If the output voltage is still low, replace the battery.
Note. Do not take battery test readings immediately after adding water to the battery.
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