Not able to power up nRF52840 using a battery pack

[sprasad]

I successfully ran the proximity_demo supplied by Nordic. I used my laptop's usb port to power up the device and it worked fine.

Then I unplugged my laptop and tried to connect the battery pack to the board. The LED5 blinks rapidly and the board switches off after 10secs approx.

Again, everything works well with my laptop usb port. Can anyone point out what mistake I'm doing here?

btw here is the battery pack I'm using 

https://www.amazon.de/Kinps-10000mAh-Portable-Externer-Intelligent-10000-Wei%C3%9F/dp/B01M0309EM/ref=sr_1_1?ie=UTF8&qid=1518799040&sr=8-1&keywords=kinps+powerbank+10000

[Edvin]

Hello,

You use the same USB on the DK when you use the external battery as when you use the laptop, right? And all the switches are in the same position?

Do you use the same USB cable when you use the external battery and the laptop? I see that the power cable that comes with the battery is a charging cable, which means that it only has GND and VDD, and none of the data lines that a normal USB cable has. I am not sure whether this would matter, but it might be that the DK does not like that an UART is initialized, and getting power through the USB, while it is not being able to actually set up the UART connection.

Can you try to use the charging cable that came with the battery and connect that to the laptop, and see if it behaves the same way? If that shows the same behavior (turning off after 10s), try to disable the logging (NRF_LOG_ENABLE) in sdk_config.h, and see if that helps.

Best regards,
Edvin

[sprasad]

Thank you! Will try these and then get back to you.

[David Edwin]

Most likely the DK does not have enough load to turn the battery pack on. Check if you can force the battery pack to ON state. I have noticed this issue in "intelligent" batteries .

[sprasad]

I tried with the same USB cable, same port and switches in the same position. Board works fine when connected to laptop, but fails when connected to battery pack.

Regarding your second suggestion, Yes! I think that is the case here! I tried with another battery pack of mine (not that intelligent ;) ) and it seems that things are working fine!! Even then there is one issue here, with my new battery pack(not intelligent one), I see that LED5 is flickering continuously! What could this mean? 

[Edvin]

I think David's theory sounds very plausible. 

LED5 is connected to the programming chip. I don't know exactly what triggers the flickering in your case, but it could be logging information (UART). You can choose to only power the nRF using SW6, which will not power the programming chip. This means that none of the leds or buttons on the board is connected, but you will still be able to use the radio, and connect to it via e.g. nRF Connect.