My 195, I have to tell it what type of batteries I am using. I think it
then measures the voltage and when it gets too low, such as for a nicad,
it shuts down to prevent battery damage. Could your 196 have some setting?

RNR wrote:

I have owned a 196 for about four years, without any serious concerns.
Last week, I encountered a problem that is serious. While the unit
works fine on aircraft power, it will not function on battery power.
It will turn on but it will shut itself off within 30 seconds. This
happens every time. Has anyone experienced this? Do I have any
chance of rectifying this without sending it back to Garmin? Thanks.
RNR