Laptop and 12V

[Sobin]

Hi


If you want to operate your laptop on the 12V on-board network, you need a voltage converter to achieve the required 16 or 19V. But if you look at the built-in battery, you can see that it usually emits a voltage below 12v. Now I am wondering whether the laptop cannot be connected directly with only 12V on-board voltage instead of using a voltage converter. I think I read that once. Hence my question; does one of you already do that or has anyone tried it?


mvh
Rüdiger

[Joh.Ghurt]

Get a car adapter to push the 12V to 16V or 19V as needed. Make sure the adapter has enough Ampere or Watt. For newer Macbooks / Lenovo, you need a USB-C power supply that delivers 70-90W Those aren't the one in the $1-bin, but you'll find them too.


That's what the battery charging circuits like to get. Don't try to be too clever and take shortcuts.

[Sobin]

I have an adapter that works, the question here is whether it is possible in principle.


mvh
Rüdiger

[Cheechako]

20 years ago I ran my laptop off the 12V system on board. I don't know if it was a good thing or not though! I also ran some of the sensitive stuff off a motorcycle battery I could isolate from the charging circuit. Especially for the PacTor stuff via the Shortwave Radio.

[Polar Opposite]

Originally Posted by Sobin

Hi
Now I am wondering whether the laptop cannot be connected directly with only 12V on-board voltage instead of using a voltage converter.
mvh
Rüdiger

It won't. You have to produce a voltage well above battery voltage in order to get current to flow into the battery, and to power the charging circuit and overcome its inherent inefficiency. In theory, if the laptop battery was less than 12v, you could tap into the battery connections with 12v direct or something less than that, but I imagine the fluctuations on your boat's 12v supply would cause havoc.

[Sobin]

And if the battery is fully charged or you take it out, then no charging voltage would be required ?


mvh
Rüdiger

[Brian.D]

Most batteries for laptops are on the order of 14.4 vdc, no load. Put a load on it and it will probably drop to 12 vdc or so. If you happen to have a spare laptop that is no longer usable (for any reason), plug it into a 12 vdc car battery and see what happens. Have fire extinguisher available, though. LOL

[Sobin]

I actually plan to do that, I'm still waiting for the right connector.


mvh
Rüdiger