Which is better, the cigarette lighter DC/AC adaptor, like this? So you’d go from DC to AC, then back to DC.
Or the straight DC converter, like this?
The AC version puts out 100 watts, the DC version puts out 70 watts. Is 70 watts enough for laptop usage? Any other considerations?
It depends upon the power requirements for your notebook. My six month old Celeron based notebook wants at least 100 watts.
Rick
The step-up converter is simpler than an an inverter+your existing adapter. Less things to fail and all that. There is also less power loss involved (less strain on the car battery). However, a cheaply made one is not better than a well made inverter. So the big question is how well are they made first, then pick the step-up converter if it’s just as good or better.
Wattage depends on your laptop plus accessories. Since each one is unique, I can give no specific recommended number. Look in your documentation.