GMC08 - Quick Installation Guide

  • Updated on November 2, 2023


GMC08 is Grandstream’s battery charging pack for its mobile telephony products, including the WP820. It features 8 independent slots to fully charge or discharge multiple batteries
For added flexibility, the GMC08 comes with three charging capacities for air shipment, storage capacity control and long endurance. It offers reliable performance and efficiency
thanks to built-in over-voltage, over-charge, over-current, and short-circuit management as well as leak protection.

GMC08 Package Contents

GMC08 LED Status

Red FlashingCharging
Green FlashingDischarging
Green SolidCharging or discharging done
Red SolidCharging or discharging error (high temperature or extreme temperature or battery contact error
LED OFFNo battery detected or battery incompatible

Charging/Discharging Batteries with GMC08

  1. Connect one end of the 12V, 2A DC output plug to the power jack on the device and the other end to an electrical outlet.
  1. Insert the batteries with the electrodes in the top right corner.
  1. Slide the battery capacity switch on the top right of the device to the desired capacity. The device will start charging/discharging the battery until the level reaches the selected capacity.
  2. Check the LEDs of each slot. When the LED turns solid green, the battery has finished charging/discharging and can be removed.

  • The three charging capacities are not exactly accurate. The lowest capacity is about 20%~30%, which mainly meets the demand for sea/land/air transportation. The intermediate capacity is around 60%, which mainly meets the demand for long-time transportation and storage. The highest capacity is around 100%, which is mainly suitable for charging batteries for daily use.
  • The battery may have power loss when finish charging/ discharging, and after a while the device will start charging again.
  • The short-circuited battery may cause GMC08 reboot repeatedly, and all the LED lights will flash. Remove the short- circuited battery will solve the problem.
  • After slide the switch to different capacity level, the charging capacities will take 2~3(s) to take effect.


  • Do not attempt to open, disassemble, or modify the device.
  • Do not use a third party power adapter.
  • Do not expose the device to temperatures outside the range of 0°C to 55°C (32°F to 131°F) in operation and -10°C to 60°C (14°F to 140°F) in storage.
  • Do not expose the GMC08 at environments outside of the humidity range of 10-90% RH (non-condensing).
  • Do not charge or discharge third party batteries that are not specified by Grandstream.
  • Do not short circuit electrodes.

Refer to online documents and FAQ for more detailed information:

For Certification, Warranty and RMA information, please visit

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