I have an anker and a zenduro charger pack. The zenduro is nicer, but Amazon had a good sale on the Anker, so I got that. The zenduro specifically mentions charging while charging, but I don't think Anker does that any more. If you are going to use a dynohub usb charger that doesn't already have a cache battery, it's best to have an external cache battery. I have a luxos u, I'm thinking of getting rid of it because I don't trust it.