Hitachi DB 3DL Technical Data & Service Manual page 14

B. Suggestions and precautions for the efficient use of the charger and storage battery
If the Type EBM 315 storage battery is exposed to direct sunlight for an extended period or if the tool has just
been operated for a long time, charging may not be possible if the temperature of the battery is above 40ûC
(104ûF). In such a case, the customer should be advised to place the battery in a shaded area with a good airflow,
and allow sufficient cooling before recharging. This phenomenon is common to all existing batteries and chargers
which employ temperature sensitive overcharge protection devices. The cooling time required before recharging
can be accomplished varies from a few minutes to about 30 minutes, depending on the load, duration of use, and
ambient temperature.
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