Do any of you know the characteristics of the cigarette lighter adapter
that is used with the Yaesu/Vertex VXA-700 2 meter and airband HT?

Does it just convey the 12 volts (or 13.8 volts or 14.2 volts or whatever
it is at any moment in time) directly to the HT, or is there any kind of
filter or voltage limiter that's internal to the adapter?

In other words, can I just feed 13.8 volts directly from a car battery to
the HT to run it and charge the battery?

Looked on the Yaesu and Vertex Standard websites for information and
couldn't find any reference at all to the VXA-700 ... wonder if it has
been discontinued...