[Eric Frank]

I do have a 10" TFT touchscreen (1024x768 pixels) which works with 12V. (look for them at ebay).
I don't know how much A the draw. Normally I do use my MacBook as chart plotter and the TFT touchscreen as external monitor.

To cut down power consumption for MacENC or GPSNavX on my Powerbook, I use a script that updates the position every 2, 5, or 10 minutes and sleeps the Mac in between taking these readings. This cuts the power consumption a lot, even taking points every 2 minutes. Works most efficiently with the older Powerbooks (not Intel) which have lower power consumption and sleep faster when you put them to sleep. Average power consumption is probably about 1 Amp. I do find that it does not work reliably with Bluetooth, as Bluetooth does not always reconnect when the Mac wakes up. But with the serial-to-USB converter, it works fine.
I am happy to share this script with anyone who would like it. Have used it for a couple of years now.

Eric