Running a Laptop Without an Inverter

[s/v Jedi]

Originally Posted by HappySeagull

mmm,well there's one thing I don't like about my 30$ xantrex inverter is the radio noise,but idle current draw is VERY low.
Inverter+T42
nothing plugged in =.06amp
JUST ac adapter plugggedinto lap =.25
running lo brite =2.04
running hibrite screen =2.62

and here is the laptop connected DIRECT to the Boat Battery-I mean,REALLY direct,where the 10.8v laptop battery supplies it....
IBM T42 startup max=2.7ampsmax
idle lobrite=1.6amps
idle hibrite=1.8amps
suspend=0.04amps
All powersaving schemes are always disabled on my machines...except closing the lid and adjusting brightness.

roughly,half an amp burned by the inverter.

See, here the inverter looses again (not by much) but it's consumption data is for a state running a program while the data for the DC-DC converter (it sounds like the power from laptop battery was used to test?) was taken while the laptop was idle?! Wouldn't it be appropriate to collect consumption stats while the computer/laptop is doing the exact same thing instead of work vs idle ?

Very simple: 12V->19V DC-DC converter versus 12V->120V inverter + original AC adapter. Test power consumption while doing the exact same thing on the laptop (laptop battery fully charged, watching DVD with equal screen brightness for example). That will provide useful test data.

ciao!
Nick.

[HappySeagull]

Originally Posted by s/v Jedi

See, here the inverter looses again (not by much) but it's consumption data is for a state running a program while the data for the DC-DC converter (it sounds like the power from laptop battery was used to test?) was taken while the laptop was idle?! Wouldn't it be appropriate to collect consumption stats while the computer/laptop is doing the exact same thing instead of work vs idle ?

Very simple: 12V->19V DC-DC converter versus 12V->120V inverter + original AC adapter. Test power consumption while doing the exact same thing on the laptop (laptop battery fully charged, watching DVD with equal screen brightness for example). That will provide useful test data.

ciao!
Nick.

I did think of that, you know.These are doing exactly the same thing.I've done lots of tests for my own interest sake....running various apps etc but the ratio is the thing and...

.Brightening the screen is increasing power consumption in steps and it's easy to be sure the same thing is happening each time....
Even though the processor is a big or bigger power consumer , who knows when the fan will come on?Likewise the DVDROM but it spins up and down.etc etc.so,there's averaging and so on involved.

In my comparison the ship's 12vbattery is running the laptop DIRECT where the laptop battery would be slid as compared to ac adapter+inverter plugged in the OEM jack.That's a pretty good comparison of inverter+AC versus "as simple as it gets"
There is no DC/DC conversion involved in any test I have made,because I don't own such a thing (as I've said)
..so,very simple as it is,you will post some numbers?

[ty.gregory]

I am so lost! I've been trying to follow along here, but can't keep up with you all. I use a laptop for writing, and will be using a laptop on a sailboat one day soon for 5 and 6 hours a day writing at anchor. I will buy whatever equipment I need to allow this to happen. My question is not how to do it, I'll figure that out later, but I can--with the right gizmos--use the laptop for six hours a day, right???? I'm looking for confirmation here.

[noelex 77]

Originally Posted by ty.gregory

I am so lost! I've been trying to follow along here, but can't keep up with you all. I use a laptop for writing, and will be using a laptop on a sailboat one day soon for 5 and 6 hours a day writing at anchor. I will buy whatever equipment I need to allow this to happen. My question is not how to do it, I'll figure that out later, but I can--with the right gizmos--use the laptop for six hours a day, right???? I'm looking for confirmation here.

There are 2 options to power the laptop from your boat batteries.

1. Buy an inverter plug the inverter into a cigarette socket (big inverters need wiring in permanently). Plug the laptop power supply as you would into a wall socket.
2. Buy a 12v DC to DC converter. This will plug into a 12v cigarette socket and the other end will plug into the laptop. It replaces the "brick" that came with the laptop.

Option 2 will use about 20-30% less power than option 1

If you are using the laptop for 6 hours a day option 2 will make a significant difference to your power usage. You may also consider getting a low power computer like a netbook for your writing.
With a conventional laptop you will be using something like 20Ahrs a day on the computer alone even with option 2. A netbook with option 2 will halve that.

Inverters are useful for other things so get one as well as a backup

[s/v Jedi]

Originally Posted by HappySeagull

In my comparison the ship's 12vbattery is running the laptop DIRECT where the laptop battery would be slid as compared to ac adapter+inverter plugged in the OEM jack.That's a pretty good comparison of inverter+AC versus "as simple as it gets"
There is no DC/DC conversion involved in any test I have made,because I don't own such a thing (as I've said)
..so,very simple as it is,you will post some numbers?

I can't follow you here... I actually have no clue how or what you test. Especially the part about "ship's 12vbattery DIRECT" and "laptop battery slid". It sounds like you connect the 12V ships battery directly to your laptop without any adapter/converter?!

ciao!
Nick.

[Albro359]

Happy Seagull...I also don't follow you here...what does "slid" mean ?

MOST of todays Laptops/notebooks need 19VDC at anywhere between 3 and 8 Amps.

There is NO WAY you can run these DIRECT FROM A 12V battery.

An earlier poster summed it up

either
1. Install a small inverter to run your laptops brick power supply (but beware some of these bricks are switchmode power supplies and need clean sinewave AC to work...cheaper inverters are invariably square wave output and sometimes won't work
or
2. do what I did and by a 12 v to 19V converter from Jaycar , Tandy, RS or similar...works perfectly

Cheers
Alan

[Mark Johnson]

We have hardwired in a very efficient, "pure sine wave" 120W inverter, that we mostly use for an hour once or twice a month to charge NiCad batteries for the handheld radio, or drill drivers. (Their chargers are sensitive, & require pure sine wave). Otherwise we leave it off! IMO, Inverters are mostly unnecessary power hogs. They consume amps even if they are not powering anything. As long as they are on, they use power.

By going really energy efficient, we get by on about 40 Ah per day, even with all the comforts. This allows us to be 100% solar powered, 95% of the time.

With that level of "Amp skimping", using our Link 10 monitor I compared using the inverter to power an "AC wall brick" with the TV, to watch a movie, VS when I later got a 12V DC to 19V DC converter, (but the inverter was off).

As I said earlier... avoiding inverter use, but instead, running computers or TVs on DC to DC converters, consumes about HALF as many Ah, as running an inverter to power the AC wall brick.

In all three of my solar powered boats, I have found that over 10 years or more... It is many times cheaper & easier to get set up for, and live, in an energy efficient boat, than it is to ignore efficiency and produce twice as much power instead.

Mark

[WoundedWarrior]

what ever route you go, make sure you unplug/disconnect any inverters/wall warts/ converters, etc... from power when not in use. they all continue to draw power even if you are not using the devices they provide for.

[s/v Jedi]

Originally Posted by Mark Johnson

We have hardwired in a very efficient, "pure sine wave" 120W inverter
[...]
As I said earlier... avoiding inverter use, but instead, running computers or TVs on DC to DC converters, consumes about HALF as many Ah, as running an inverter to power the AC wall brick.

This means either you did use another inverter or it isn't nearly as efficient as you think it is. When it consumes twice as much power as a DC-DC converter, there is something really wrong with it... or something else was different ruining your comparison.

ciao!
Nick.

[HappySeagull]

Originally Posted by Albro359

Happy Seagull...I also don't follow you here...what does "slid" mean ?

MOST of todays Laptops/notebooks need 19VDC at anywhere between 3 and 8 Amps.

There is NO WAY you can run these DIRECT FROM A 12V battery.

An earlier poster summed it up

either
1. Install a small inverter to run your laptops brick power supply (but beware some of these bricks are switchmode power supplies and need clean sinewave AC to work...cheaper inverters are invariably square wave output and sometimes won't work
or
2. do what I did and by a 12 v to 19V converter from Jaycar , Tandy, RS or similar...works perfectly

Cheers
Alan

"slid" as in :to slide.You know,where your laptop battery slides in.

And,there IS a way to power some laptops directly as I said...and as I do.Unless the panels are pumping above where I feel alright about it...
I haven't seen the same for a dc/dc converter,but I would like to.
I am repeating myself and so I'll give up.

[s/v Jedi]

Originally Posted by HappySeagull

"slid" as in :to slide.You know,where your laptop battery slides in.

And,there IS a way to power some laptops directly as I said...and as I do.Unless the panels are pumping above where I feel alright about it...
I haven't seen the same for a dc/dc converter,but I would like to.
I am repeating myself and so I'll give up.

Aha, I think I decoded this... you power the laptop by applying 12V from your boat's battery to the contacts of the laptop battery slot. Yes, this is possible for some laptops.

However, you have no power conversion outside the laptop at all for this. This means that the 20-30% extra consumption when using the inverter is the total overhead, not relative to using a DC-DC converter. My estimate is that a decent DC-DC converter will be 10-20% more efficient than a decent inverter + std. laptop psu. The reason is as stated by others before: matched components, often a single-chip or hybrid module solution.

But now you're mentioning "raging panels above" and while my first guess is that you mean solar panels, it's time for me to give it up in this thread too

ciao!
Nick.

[arne]

Has anyone considered or are using 12 volt computers from islandtimepc.com
Seems to me that they are made for yachts connected directly to the ships 12V power supply.

[Music]

Originally Posted by arne

Has anyone considered or are using 12 volt computers from islandtimepc.com
Seems to me that they are made for yachts connected directly to the ships 12V power supply.

Well they do offer complete systems.
You can do the same if you are so inclined. They are using what is called a Mini-Itx form factor motherboard and case. You can get these things pretty cheap with the 12Vdc supply. Just search for mini itx motherboards and you will find what you need for your own custom system for your boat.