October 17, 2006 05:08
I have used an older kensington 12V airline/car adapter for several years with G4 iBooks with great success. I hooked up an ampmeter as well just to see and the charger draws almost exactly 1A@13V which is very good (it draws about 1.8 A if the battery is in need of a charge. ) I don't think they have the new magnetic plug yet though for the latest macbooks.
AC Inverters are not a very good choice because they waste about 50% of the power they transform.
One other trick to save power: If I am sailing in clear water and not navigating a tight passage, I just close the computer and wake it up when I want to see where I am. I asked the GPSNavX guys to modify the route function so the route is continuous even if there is no new data for an hour or so. (They kindly did the modification) In this way I can easliy navigate a full day on just one battery charge. I have a SIRF III usb dongle that I use sometimes and I remains powered up even with the Mac sleeping so you don't need to wait for a new fix.
AC Inverters are not a very good choice because they waste about 50% of the power they transform.
One other trick to save power: If I am sailing in clear water and not navigating a tight passage, I just close the computer and wake it up when I want to see where I am. I asked the GPSNavX guys to modify the route function so the route is continuous even if there is no new data for an hour or so. (They kindly did the modification) In this way I can easliy navigate a full day on just one battery charge. I have a SIRF III usb dongle that I use sometimes and I remains powered up even with the Mac sleeping so you don't need to wait for a new fix.