Craftsman 934.716140 Owner's Manual page 31

CHARGING BATrERIES WITH BUILT-IN HYDROMETER "EYE"
Specific Gravity Illustration
charge. After the two layers of electrolyte finally mix, the "eYe" will
register full charge.
This problem has lead Delco to recommend the gentle shaking of
a Freedom battery once each hour during charging. This helps
mix the stratified electrolyte.
With this particular fully-automatic battery charger, when the
CHARGE COMPLETEindicator lights up, the battery is at full
charge. The "eye" on the battery wilt probably not indicate full
charge, but the battery is indeed at full charge. After sitting for
awhile (usually an hour or two, but possible as long as a day), the
electrolyte will mix and the "eye" will indicate full charge.
Non-automatic chargers will more readily get the "eye" to indicate
full charge, but is accomplished through overcharging. This
causes the electrolyte to bubble and gas, which mixes the
stratified electrolyte quicker. This practice is not recommended,
especially on deep-cycle batteries, as it is harmful to the battery
over time.
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