I have a 5V USB passthrough that I use predominantly with the 2A/USB adapter from madvapes. I would like to get a generic 510 adapter (I assume 3.7V). My question is two-part. Unless it specifically says 5V, can I assume it's 3.7? Also, once I track down a lower voltage pass-through, can I use it on the adapter I currently have, or do I need a different adapter for the lower voltage passthrough?