[Kenwood] thg71a charging question

[Roy Nickelson]

Hi,
I have a thg71a it is my primary rig. I use it with a radioshack 3 amp 13.8
power supply most of the time.  I keep a empty alkaline case on the radio
most of the time.  When I am away from the house I use the 9.6 nicd battery
that came with the radio.  When It goes dead I charge it with the original
charger that came with the radio.  This takes me off the air for 15 hours
because I don't want to use that charger as a regular power supply.  Can I
use the radioshack power supply as  a charger and still run the radio at the
same time?  Will it take 15 hours to charge it this way?  Also what is the
voltage and current on the original charger?
Roy