I would like to run a standard notebook computer from a 12V deep cycle battery for mobile applications.
In theory, which of the below is more efficient, given the same amp draw, about 2A average?
Thank you for any insight.
Leon Eddings
Number 2 (especially if it was a simple boost converter with no input output isolation) would normally be higher efficiency than the 120 to 18 volt supply. And using it eliminates one power conversion (the 120 to 18 volt supply), so that, alone, should produce 10 to 20% more efficiency. If the notebook will run on 12 volts, a direct connection (through just a fuse) would eliminate all external conversions and be most efficient.
I am not responsible for any damage caused by the experimental test of this possibility.
I used three 6V lead acid batterys in series to run a laptop. Why not just start with the right voltage?
When I tested it with a variable psu the old laptop I had worked down to about 10.5v. It drew more current than running at 18V. It normally used about 40% of the rated power of the mains psu so it would probably have been fine on 12V without the sound , USB, and CDROM using power.Other models may vary.
Bob
Another consideration is the health of the laptop. It has its own switching power supplies inside, which present a pretty weird load to the external supply. Laptop bricks handle this well, but cheap 'n' nasty switchers might not, and it's quite hard to test for without putting the computer at risk. If you're using an expendable laptop, go for the gusto, but if it's your pride and joy, stick with an AC inverter and the normal laptop power brick.
Cheers,
Phil Hobbs
I agree. Not having to buy a new laptop is the most efficient. I wouldn't even trust an AC inverter where "an" means any old POS inverter. I vote for 18V DC from batteries. Charge them with any old POS inverter and a good charging circuit.
The OP did ask stipulating "in theory" and got good answers to that question.
Ed
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