Can I charge a USB 501 Passthrough via my regular charger?

[nitemarch]

Hi I have a usb passthrough for my 501. It has a battery in the box between the USB plug and the e-cig body. Battery seems dead, just died! Won't accept a charge of the computer, however when I plug it into my wall charger the charger light turns red and it is accepting a charge. Do you think this may revive my passthrough for a while? Is it safe to charge this way?

[nitemarch]

just took it off the charger for a bit to test and it was working! Have placed it back onto my USB port to continue charging. Seems like the battery was too dead (was smoking it unplugged from USB a lot) and wouldn't accept a weaker current from the USB.