Denver GSP-131 User Manual page 4

Charging the battery: charge the battery before starting to use
the device. Connect the charger to a mains wall socket, and
then plug the jack into the charging base (wait for a moment until
an audio feedback notifies the charging start) or put it directly
into the micro USB port on the right side of the phone. When
charging has been completed/is complete, a second audio
feedback will be heard
Attention: To preserve the functionality of the product and the
integrity of the warranty, we recommend the use of original
chargers. Please charge the battery indoors, in a dry and
favorable environment. It's normal for the battery to get slightly
warm during the charging process. The battery will reach its full
capacity only after several complete charging cycles.
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