There are 24V in the truck. The laptop power supply turns 240v ~ 19v--. Can I operate and charge my laptop with 19v from a stepdown voltage converter?
Queta LM2596 DC-DC Step Down Voltage converter Switching regulator LED voltage display https://www.amazon.de/...08HMGQ44S/
Yes, that would work. But I would rather use a voltage converter from 24V to 230V in your place. You can use it more flexibly and then connect the notebook power supply directly.
I have a converter to 240v. But then I transform up once and then down again, with the corresponding losses. That's exactly what I want to avoid.
That's true, of course, but with current converters, the losses are actually not that great.
But if you want to use the stepdown converter (at first glance nothing speaks against using the one you posted as an example), then you need a cable with a suitable connector for the notebook. The notebook manufacturers sometimes use connectors that are difficult to get.
