Low power draw laptops that can run on direct 12v

[nicaland]

I bought one of the 12V corded bricks to run my 15" HP laptop and am very happy with it. Power consumption has not been a concern for me given the fact that the longest I have run it at a given time without charging my house batteries has been around 3-4 hours (watching a DVD and a bit of web surfing). Plus, I can use it in any other car, boat, etc. when needed without having to lug around an inverter with it.

[kmrotterdam]

Check online and see if a 12-volt adapter is available for your particular notebook. I bought one for my Asus notebook, but now I have a notebook that is charged by USB: https://www.amazon.com/gp/aw/d/B01K1...op_mb_pd_title

[Anachr0n]

As for your quest for a low power draw laptop that connect to 12V; the new Macbook Air uses a 30W USB-C power adapter and a separate cord rather than the cord permanently connected to the brick. This allows you simply buy a "cigarette lighter" type of adapter with a 30W USB-C output.

Here's one for $12.99 on Amazon.

[booster]

Originally Posted by Anachr0n

As for your quest for a low power draw laptop that connect to 12V; the new Macbook Air uses a 30W USB-C power adapter and a separate cord rather than the cord permanently connected to the brick. This allows you simply buy a "cigarette lighter" type of adapter with a 30W USB-C output.

Here's one for $12.99 on Amazon.

Have you had an opportunity to physically measure the watts in/watts out of the USB charger when it is running at some various loads?

[Anachr0n]

Originally Posted by booster

Have you had an opportunity to physically measure the watts in/watts out of the USB charger when it is running at some various loads?

No, I don't have this laptop... yet . It seems to suit Etzu's needs though. Apple sells a 36W Belkin charger, albeit at $29.99, and lists the new Retina Macbook Air as being compatible.

[hbn7hj]

In today's electronic laden world most have given up on chasing milliamps and started adding amp hours. More battery. Most of us just want more than what we have, some want to run A/C on battery.

Put your mind to getting more battery. Chasing milliamps is now second place.

[Anachr0n]

Originally Posted by hbn7hj

In today's electronic laden world most have given up on chasing milliamps and started adding amp hours. More battery. Most of us just want more than what we have, some want to run A/C on battery.

Put your mind to getting more battery. Chasing milliamps is now second place.

Agreed. Milliamps aside, I like the idea of not having to run an inverter just to charge my devices. We're just starting our search for an RV and currently still tent camping. My car has a 12V jack in the arm rest that remains energized even when the car is off. I wouldn't want to leave a portable inverter plugged in for hours on end, but I do leave my phone and tablet plugged in and hidden. I would like to do the same with a laptop in my RV, ideally somewhere less visible than the dash plug in the cab.

[booster]

Originally Posted by Anachr0n

Agreed. Milliamps aside, I like the idea of not having to run an inverter just to charge my devices. We're just starting our search for an RV and currently still tent camping. My car has a 12V jack in the arm rest that remains energized even when the car is off. I wouldn't want to leave a portable inverter plugged in for hours on end, but I do leave my phone and tablet plugged in and hidden. I would like to do the same with a laptop in my RV, ideally somewhere less visible than the dash plug in the cab.

If you think about it all, you are likely running just as much power conversion stuff with the USB charger as you would with the inverter and the factory AC brick.



On inverter 12v to 110v to laptop battery voltage


On USB charger 12v to 5v to laptop battery voltage


There have been a few discussions on the forum about the benefit these days of having all 12v adapters, and IMO it is getting more obvious that it probably is not any real benefit in most cases.


I have measured the actual 12v power usage through 12v adapters vs using a 120 watt PSW Samlex inverter with the factory brick and found no difference to an advantage when on the inverter of less power use.



When we started out a decade ago, we got all the 12v adapters, which also were quite unreliable over time. As the laptops, TVs, DVD players, etc started going to higher than native 12v, we found out it was better just to use the Samlex for that stuff, and we don't have to chase all over to find adapters for everything, just plug in.


My understanding is that the factory bricks will also have the best quality power around when compared to the aftermarket adapters, but haven't tested that myself.

[Anachr0n]

Thanks for your insight Booster. I guess I have to start thinking differently now that we're looking at a camper vs camping.

[GeorgeRa]

I have 2 inverters, 1000W Magnum MS1012 Inverter/charger and 300W Morningstar. Outlets from Magnum MMS1012 provide either shore or the inverter power. The Morningstar 300W is connected to 2 different outlets.

For the microwave or other higher power devices I use Magnum. For lower power I use 300W Mornigstar. The key reason is idle power draw, Magnum draws over 1.5A at idle or less at search mode which annoyingly clicks especially at night. Mornigstar 300W is very quiet no fan, more efficient, and draws at standby 55mA.

The picture shows galley’s panel with one outlet powered by Magnum/Shore and other one by Mornigstar with the switch within the outline.
So, my advice is to look at standby specs and aim for an inverter size corresponding to your actual needs.

[booster]

For those thinking of small inverters for the purposes being discussed, or any other purpose, be aware of the two terminologies that are used to describe wasted power.


No load power consumption (or the commonly called parasitic load) is what the unit consumes when it is on, ready to go, but not putting out any output power.


Standby, Search, Scanning, etc mode power is if the inverter is on with no output, but it is not really ready to invert immediately. It will be monitoring the output for a load coming on, and then will turn on the output. This mode is usually much less than the parasitic load, but the mode can be an issue in some cases due to the scanning and delays. We have found it much simpler just to turn inverters on or off as needed, as we have no continuous AC loads unless we are running the AC on shore power.



In the examples of the two inverters George has, the Morningstar has 55ma in the standby mode, but is consuming just under .5 amps when inverting per their literature, and that would likely also be the parasitic load.


The 2000 watt Magnum, which we also have, is rated at 2 amps of parasitic and 8 watts in Searching mode. As George mentioned, the Magnum beat spec by quite a bit, as ours runs about 1.4 amps parasitic.


The 120 watt Samlex that we use is rated for parasitic at "less than .5 amp", and the two of them we have run closer to .2 amps.


What I have tested a little is to try to find out if the parasitic stays constant and is piled on top of efficiency of the inverter, or not. A couple of tests I did with the Samlex would seem to indicate that it is not constant, as when I put on small loads, the input current didn't rise by that many watts. This is still something I need to look at more, including for the Magnum.