Running a Laptop Without an Inverter

[s/v Jedi]

Originally Posted by Weyalan

We are only using the inverter when we are motoring, for now.

huh? you have no house batteries? What makes you think a DC-DC converter will change so that you can use it without running the engine? We're talking about very small DC draws for a laptop (and probably charging it's battery), right?

For the posters who state that the draw is double while using an inverter... check your draw with the inverter on but without the laptop connected (idle draw from inverter). I am sure that a laptop with it's AC adapter draws less power than with a DC-DC converter. It's just how do we create that AC power source and at what efficiency. Improving that efficiency has a positive effect for all your AC powered appliances aboard while using a DC-DC converter for a laptop only helps for that laptop.

cheers,
Nick.

[arjand]

DC Power Adapters for Dell Computers

Not just Dell, a lot more....

[Mark Johnson]

Originally Posted by s/v Jedi

huh? you have no house batteries? What makes you think a DC-DC converter will change so that you can use it without running the engine? We're talking about very small DC draws for a laptop (and probably charging it's battery), right?

For the posters who state that the draw is double while using an inverter... check your draw with the inverter on but without the laptop connected (idle draw from inverter). I am sure that a laptop with it's AC adapter draws less power than with a DC-DC converter. It's just how do we create that AC power source and at what efficiency. Improving that efficiency has a positive effect for all your AC powered appliances aboard while using a DC-DC converter for a laptop only helps for that laptop.

cheers,
Nick.

I was talking about using the 12VDC to 19VDC car adapter with cigarette lighter plug, to say... watch a movie. It is half as many Ah to do so, vs if I used the inverter to create 120V and then reduce that to 19V DC with the factory supplied AC black box.

I use the DC to DC converters to avoid the load from having the inverter in use at all. Compared to the inverter way of doing it, (shutting the 120V inverter off), and using DC to DC converters to run 19V appliances, uses a bit less than half as many Ah.

I measured with my "Link 10", with all charges in or out off, except the TV.

We avoid the use of our inverter except occasionally, to charge nicad batteries and the like. Inverters are very inefficient ways to do it.

Mark

[Weyalan]

Sure we have batteries - 2 x house at 100AH each (and 1 x engine which is less AH but more cold cranking amps), but I am so suspicious of "electrickery" I try not to use it unless I has to!

[sctpc]

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[noelex 77]

Originally Posted by s/v Jedi

For the posters who state that the draw is double while using an inverter... check your draw with the inverter on but without the laptop connected (idle draw from inverter). I am sure that a laptop with it's AC adapter draws less power than with a DC-DC converter. It's just how do we create that AC power source and at what efficiency. Improving that efficiency has a positive effect for all your AC powered appliances aboard while using a DC-DC converter for a laptop only helps for that laptop.

cheers,
Nick.

Nick you make a good point about the idle current of the inverter. If the inverter has to be on anyway to operate other devices the power savings using a DC to DC converter for the laptop will be less.
The DC to DC converters, however, are still typically a bit more efficient than an inverter.

[Filipo]

Originally Posted by SV Escape Plan

I am trying to find a "car charger" for my laptop but am not having much luck so far. I currently use the inverter to run the laptop but would prefer to go to a DC source. I have a Gateway FX series laptop whose power supply says 19.2 Volts DC 6.4amps I believe. Went to best buy and they just wanted to sell me an inverter did not understand what i was looking for. When I try the online stores none seem to recognize my "FX" series. The all suggest MX and other Gateway series. Perhaps someone here with bettter search skills can point me to a DC laptop plug for my FX series Gateway?

Also was out on the boat yesterday and tried charging my iPhone via the AC plug and inverter. It was not enough draw to kick on the inverter so will stick to DC charger there too.

Just check the web page that I have found for DC to DC converters. I am sure there should be much more :

http://www.powerstream.com/ADC.htm


Best of Luck

filipo

[AfterHoursNLCT]

Originally Posted by HappySeagull

Weyalan...is it a DELL? I know many of these have a third wire at the dc jack...Perhaps other makes do too,nowadays.They can likely be tricked but....

That's what I was thinking (a Dell). They can be fooled into using a conventional power supply but you'll need to Google it to find out how (I think it involves jumping the sensor line with a resistor).....LL

[AfterHoursNLCT]

Found this on the web....

"Well the "smart-pin" adapters have 3 connections, here's a picture of the socket:

wwwtelefonicanet/web2/informatica/skt.jpg

Ground is on the outside as normal, +19 volts on the inner ring and the center is where the "smart-pin" goes.
If you only apply power to the inner & outer rings the computer will not power up. You need to apply +19 to the center pin as well.
According to HP "The Smart technology signals the power rating and if maximum rating of the adapter is reached, the notebook will reduce its power consumption"."

[s/v Jedi]

Originally Posted by Mark Johnson

I was talking about using the 12VDC to 19VDC car adapter with cigarette lighter plug, to say... watch a movie. It is half as many Ah to do so, vs if I used the inverter to create 120V and then reduce that to 19V DC with the factory supplied AC black box.

Exactly. My argument is that half the load you see while using the inverter is actually the idle power consumption of the inverter. If it's a lot of Ah, you can improve that with a more efficient inverter. On the other hand, if you need the inverter for something else anyway, it's doesn't matter and roughly both options use same power.

Originally Posted by Weyalan

Sure we have batteries - 2 x house at 100AH each (and 1 x engine which is less AH but more cold cranking amps), but I am so suspicious of "electrickery" I try not to use it unless I has to!

Okay, you are on very low power with the 200Ah house bank. I agree you can only use the computer while motoring.

Originally Posted by noelex 77

Nick you make a good point about the idle current of the inverter. If the inverter has to be on anyway to operate other devices the power savings using a DC to DC converter for the laptop will be less.
The DC to DC converters, however, are still typically a bit more efficient than an inverter.

Exactly. I'm afraid my argument is a bit too technical and hard to follow so it's good to see your msg

I always have this other argument: if you need to do things like this you should use a (miniature) desktop computer instead of a laptop. It's crazy to charge a (laptop) battery from your house battery. It's also very power inefficient. Think of the combination of house batteries and a small pure sine inverter as a "on-line type" UPS and use that to power a MacMini instead of a MacBook

ciao!
Nick.

[HappySeagull]

Originally Posted by AfterHoursNLCT

Found this on the web....

"Well the "smart-pin" adapters have 3 connections, here's a picture of the socket:

wwwtelefonicanet/web2/informatica/skt.jpg

Ground is on the outside as normal, +19 volts on the inner ring and the center is where the "smart-pin" goes.
If you only apply power to the inner & outer rings the computer will not power up. You need to apply +19 to the center pin as well.
According to HP "The Smart technology signals the power rating and if maximum rating of the adapter is reached, the notebook will reduce its power consumption"."

AfterHours,Thanks for tracking that down!That's a help!I didn't know how general it was per other laptops too...

[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.

[Lancerbye]

I am finding this discussion interesting and amuzing. If you wish to use a DC to DC converter instead of an inverter you are in effect using an inverter with a dedicated output. Inside the converter is a low current inverter, a transformer and a rectifier. They are just small and limited in use for a single purpose.

[noelex 77]

Originally Posted by Lancerbye

I am finding this discussion interesting and amuzing. If you wish to use a DC to DC converter instead of an inverter you are in effect using an inverter with a dedicated output. Inside the converter is a low current inverter, a transformer and a rectifier. They are just small and limited in use for a single purpose.

As you point out to convert the voltage both a DC converter an inverter have to go through an AC stage, but that is where the comparison ends. An inverter has to produce a very specific voltage, frequency and even shape. In a DC converter the AC characteristics are open and the electronic engineer can use whatever voltage and frequency is most efficient (and cost effective)

No matter what the reason I have yet to see a DC converter that’s not more power efficient than an inerter and saving power is important for most cruising boats.

[HappySeagull]

Originally Posted by Lancerbye

I am finding this discussion interesting and amuzing. If you wish to use a DC to DC converter instead of an inverter you are in effect using an inverter with a dedicated output. Inside the converter is a low current inverter, a transformer and a rectifier. They are just small and limited in use for a single purpose.

...that's what I surmise(not having one but guessing they must convert to AC anyways and opinions here back this up!)...I mean,these dc/dc converters seem expensive for what they do.
Compare..

dc/dc is: BoatDC -->[DC/DC adaptor internal...AC-->rectified and regulate]--->LaptopDC

inverter is:BoatDC-->[Inverter internal..AC]-->[laptop adapter internal rectify and regulate]--->LaptopDC

It seems outwardly like saving an saving efficiency "step" but is not, in fact.
Those that are having huge drains at the inverter,I'd suggest getting a 200 -300 watt one for 20-30$...but,I'm standing by for opposing data!

That said,there IS a simple way without the "loss".Add a 6 volt battery to your boat bank or use 4 as optional 12,18,24 supplies...18 runs many laptops,I bet.(12 runs a few..)The 24 could be regulated down fairly easily but of course the 4-5 volts burned off is waste,i guess.oh well.