Charging off of dynamo with USB charger device is possible while riding. I believe @hippy has successfully done this or at least charged using a USB powerpack while on the move.
Yeah, both TABRs my battery went flat on or just before the highest point - Hoosier Pass. No changes of gear at all.
Pulled over and plugged USB cable into Igaro and then into the junction box and had shifting back instantly. Also just charged it off USB battery pack in top tube bag during TCR.
Yes you can.
Charging off of dynamo with USB charger device is possible while riding. I believe @hippy has successfully done this or at least charged using a USB powerpack while on the move.