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 6 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.

Unscrew the back lid and remove it.
Take out both cells and then try to disconnect each connector as gently as you can (try to use force on the white plastic, not the cable!). Be carful about the thermal probe.
For long term storage, screw the lid back onto the bay now and continue with the rest of the steps when you want to start using Brian again.
Connect the first cell to upper battery connector and insert it inside inside the bay.
Install the thermal probe on top of the first cell.
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.
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.
Place the lid onto the bay and screw it back in.
The brick may be turned on now. Just check it and turn it off if you dont want to use it right away.