PowerShield - Why the warning?

[Sergegsx]

Hello, I was wondering why this warning?

avoid plugging the USB without LiPo battery attached.

http://lowpowerlab.com/powershield/#features

Thanks!!

[Felix]

Because USB is only used for charging so no point in doing that.
Also there is no load balancer circuit on PowerShield, battery directly wired to the charger and the USB directly wired to USB so basically the charger is told to charge a non-existent battery load.
Sometimes the charger LED tends to flicker if there is no battery source. The charger I use is MCP73831 which is a great cheap charger when used properly but can smoke if used improperly. I have not seen this charger smoke when it had 5Vin but no battery, but I wanted to add this warning/recommendation so people would better understand how to use it properly.

[Sergegsx]

Thanks Felix!

I thought I was missing some kind of dangerous issue.
For anyone interested, this is a very nice article about "load sharing" using this same chip.

http://blog.zakkemble.co.uk/a-lithium-battery-charger-with-load-sharing/