Can I hook this light up directly to my eBike battery?

Short answer: for now, only if your eBike has a USB output...

Can I leave my light on the charger forever?

Yep! There is no way to mis-charge your light, more detail here...

How do I extend runtime with a external USB power bank?

Plug a USB power bank into the light from the start of the ride and it will charge while you go, giving you much more runtime when you need it, read on for more specific details.

How should I store my light in the offseason?

You mean if you have an off-season, eh? Just top off the charge and keep them indoors, easy enough!

I charged my light overnight and it's not full, why?

Entirely depends on your USB charger's specifications... (read more)

What is Pass-Thru Charging?

Will any USB Charger work? What about PD?

Short answer: yes, some faster than others, more detail here...