Duracell POWERPACK300 Owner's Manual page 41

Battery Maintenance
&.
CAUTION
Due to inherent self-discharge, lead acid batteries must be charged
at least every 3 months, especially in a warm environment. Leaving
a battery in a discharged state, or not recharging every 3 months,
may result in permanent battery damage and poor jump-starting
performance.
&.
CAUTION
Do not attempt to recharge the Duracell® Powerpack battery if it is
frozen. Gradually warm the frozen battery to
ooe
(32°F) before
recharging.
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