Samsung SP-P310ME - Manual (Page 13)

Hold the back of the projector and lift it up while sliding the latch on the back of the battery to the left ( ).
3. Battery Use Time
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Operating time : Up to 2.5 hours when fully charged
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Charge time : About 3 hours when charging separately from the projector
4. Charging the Battery
Charging the battery when the battery is separated from the projector.
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Adapter Standard : DC 14 V, 3.5 A
Charging the battery when the battery is installed under the projector.
5. Battery Use Instructions
Please follow the instructions below when using the battery.
Use only a designated battery.