Powering My Netbook / Laptop

[svcambria]

"I have been told you can run the laptop fine at 12 volts but it wont charge the battery. Thats fine normally on a boats nav station laptop"

That has been my experience. However - some laptops will run off the 12V independent of battery state, and some will try to charge the battery whenever it sees it is low and overwhelm the system - now it wants upwards of 19V - shutting it down. There doesn't seem to be any way to determine how a computer will react until you buy one - it just isn't part of the specs. If the one you got needs the battery charged before it will work on 12V, I found that charging it up with an inverter and then running it off 12V and not letting the battery discharge will work.

Michael

[richardhula]

Originally Posted by svcambria

"I have been told you can run the laptop fine at 12 volts but it wont charge the battery. Thats fine normally on a boats nav station laptop"

That has been my experience. However - some laptops will run off the 12V independent of battery state, and some will try to charge the battery whenever it sees it is low and overwhelm the system - now it wants upwards of 19V - shutting it down. There doesn't seem to be any way to determine how a computer will react until you buy one - it just isn't part of the specs. If the one you got needs the battery charged before it will work on 12V, I found that charging it up with an inverter and then running it off 12V and not letting the battery discharge will work.

Michael

Firstly laptops & netbooks don't have a common DC input voltage requirement. It varies from model to model between 12 to 24 volts. That is why universal DC to DC adapters offer a switchable output voltage to match requirements.

Having said that I have managed to run/charge a Toughbook requiring 15 volts directly from my 12 volt battery system but only with the engine running holding batteries at 14.5 volts.

Bottom line I wouldn't recommend doing that in anything other than emergency - go to Walmart & buy a universal DC to DC adapter with output power exceeding max requirement of laptop & range of connectors to match. e.g. I have 120 watt one on Acer requiring 90 watts max - doesn't get hot, little or no RF interference.

[SailFastTri]

Most laptops are designed and rated for 15-19.5v on the input. Low voltage on the input = higher amperage draw on the circuit (if it doesn't shut itself down). In the end it will draw the amount of power it needs (watts) but current (amps) load is a wiring and fuse consideration, and might even result in internal component overheating inside the laptop (not good).

[svcambria]

Firstly laptops & netbooks don't have a common DC input voltage requirement. It varies from model to model between 12 to 24 volts...

Bottom line I wouldn't recommend doing that in anything other than emergency

Certainly. Check the AC adapter, it will tell you what the maximum output should be. I have not personally run across a 24 volt system, but that doesn't mean they don't exist ;-) (All Indians walk in single file - at least the one I saw did...)
My analogy would be that running on unregulated 12V is like driving a car with the skinny little spare tire on - it gets you where you need to go but you don't want to push it. I did use 12V direct from the house battery bank to a Toshiba laptop on a seven week 6800 mile trip across the Pacific and did not suffer from any voltage spikes or low voltage conditions but I wouldn't intentionally set out that way. That passage got me to get a Lind DC/DC converter - the high end stuff at $160 - but most laptop vendors carry a car adapter for their models at much less cost.

Michael

[richardhula]

Originally Posted by svcambria

Certainly. Check the AC adapter, it will tell you what the maximum output should be. I have not personally run across a 24 volt system, but that doesn't mean they don't exist ;-) (All Indians walk in single file - at least the one I saw did...)
l

Apple Notebooks use (or did) the higher voltages I mentioned - clearly there is no way they could be powered directly from 12 volt battery bank under any circumstances.

[Patrick_DeepPlaya]

Check out the Carnetix DC-DC regulators
DC-DC Regulators for CarPC automotive computers
Good FAQ on them at MP3car.com's forum:
FAQ - Power Supplies Explained - MP3Car.com
FAQ - Will xxxxx Power Supply Work with My System? - MP3Car.com