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Battery and charging

Brian has a built in lithium-ion battery, hidden behind a back lid. Read long term storage and service for more information.

Charging

To charge the battery, connect Brian to a USB-C charger. Brian supports fast charging from PD (power-delivery) chargers or PD power banks. When you don't have a PD charger, you can still charge using a normal 5V usb charger using USB A to C cable, but the charging will be slow.

Note

Brian can be charged while in use. Note that when the power consumption is high (motors running) it may happen that the robot will be slowly discharging even when connected to the power source. This is indicated by red status led and slow charging icon in the status bar (see statuses, errors, indicators)

Battery life

Battery capacity is 22.2Wh - 3Ah @ 7.4V (2S, nominal 3.7V.)

Expected battery performance:

Scenario Capacity change Duration

Classical line follower robot

  • Moving robot with two wheels
  • Average speed of 640°/s
  • Full brightness
  • EV3 color sensor connected

 Start at 100%, died at 20% 180 min

Line follower robot continued

  • Same as above, at speed 120°/s

 Start at 20%, died at 10% 20 min

Idle

  • Menu screen
  • Full brightness
  • No peripheries connected

 Start at 100%, died at 5% 10 h

Idle (low brightness)

  • Menu screen
  • 10% brightness
  • No peripheries connected

 Start at 100%, died at 2% 20 h

Fast charging

  • 22w charger
  • No motors connected, full brightness

 5% to 70% 30 min

Fast charging continued

  • Conditions same as above

 70% to 100% 110 min

Fast charging (slower)

  • 10w charger
  • No motors connected, full brightness

 5% to 70% 90 min

Fast charging (slower) continued

  • Conditions same as above

 70% to 100% 110 min

Slow charging (normal USB)

  • 2.5w charger
  • No motors connected, 10% brightness

 5% to 70% 11 h

Please note that these measurements are indicative only. Your milage may vary, as battery charge/discharge rate depends on lots of factors, such as the age of the battery, surrounding temperature, exact power draw (motors/sensors/brightness/heavy computations/...) and many other factors

Tip

Brian can be charged while in use. To prolong your project's runtime, place an external power bank into your robot and run while connected. USB-C PD power banks are recommended for this use case.

Long term storage and service

Batteries are not designed to be replaced or disconnected during a normal operation. However, in some specific scenarios, they can be replaced:

  • When the battery is old and does not hold capacity very well. In this scenario, batteries can be replaced.
  • When storing Brian for a long time (for example, more than 3 months) without it being used, it is recommended to disconnect the batteries or even remove them from the case.

How to remove and reinstall the battery

Danger

Please follow this tutorial carefully, as an error in the re-installation may result in ineffective battery protection, which in some circumstances may lead to a battery fire.

  1. Unscrew the back lid and remove it. There are two screws, as indicated byt the arrows. Battery unscrew the back lid

  2. Prepare your battery removal tool. If you misplaced the one that came with Brian, you can 3D print your own: TODO printables Battery removal tool

  3. Gently pull out the battery cells, with the cables still connected. Make sure their weight is not supported by the cables, but are placed od a surface or you are holding them in your hands. Battery cells removed from the case

  4. Insert the battery tool from the side, until it slides into both of the connectors. Insert the battery removal tool

  5. Wiggle with the battery tool side to side gently, while pulling on it. Wiggle with the tool

  6. The battery cells are now safely disconnected Wiggle with the tool

  7. For long term storage, screw the lid back onto the bay so you don't loose the cover or the screws.

  8. To start using Brian again, continue with the rest of the steps: Battery cells outside

  9. Connect the first cell to upper battery connector and insert it inside inside the bay.

  10. Install the thermal probe on top of the first cell. Battery cell thermal probe

  11. Connect the second cell into lower battery connector and insert it inside the bay. Make sure that the thermal probe is placed between the cells! If battery cable is not long enough, just place the second battery flipped.

  12. Put the cables inside the bay and try to arrange them to not get clipped by the battery cover. Try to do it as the image below suggests. Battery cells inside the bay

  13. Place the lid onto the bay and screw it back in.

  14. The brick may be turned on now. Just check it and turn it off if you don't want to use it right away.