Best power system for computer

digby sailor · Feb 25, 2010

adapter

for what its worth which probably isnt much from what I can gather the larger the inverter the more dc power it takes to run the inverter.for example i had an inverer which i beleive was 400 watts and im pretty sure it had a fan on it so theres more power being sapped from the batteries.what I did on my boat was I bought a cheap 75 watt plug in inverter which will run my laptop and thats about it.However thats all I want to run so im good with that.Big inverters look impressive and you may be able to run alot with them but they are hard on batteries.In my opinion when it comes to inverters less is more.Im thinking it will use more power to run your 400 inverter than it would to run a 75.The idea of going with a direct dc power source to power the laptop is most certainly the best way to go.

sailingdog · Feb 25, 2010

You can buy an automotive power supply for your laptop from Targus, iGo or any number of other companies. These are designed to work by plugging into a 12 VDC cigarette lighter style accessory plug

Of them, I'd recommend the iGo units, since most of them can also double as a cell phone/PDA/DS charger as well as charging your laptop.

Bob J. · Feb 25, 2010

Alot of over the road drivers use the plug in to the cigarette lighter type of inverters, (400 -700 watt) to charge their laptops & cell phones while the truck is running down the road.

I'd look at the power draw between the 400 watt inverter that you currently own & the 12 volt type of unit to see which unit draws the least from your battery bank. You'll also need to consider the length of charging time. My experience with any of the 12 volt type of devices that we use on the road is they take longer to get the job done. Case in point, a cell phone typically charges faster when hooked up to line voltage device when compared to the 12 volt cigeratte lighter.

Don12364 · Feb 25, 2010

Joe,
You are right.
Put your hand on the laptop's power brick and it is warm. Then put it on the 400W inverter and this is warm too. All power from your boat's battery!
Put your hand on a car to laptop power supply and it is wasting the same amount of that as the original power brick. A single conversion is more efficient - approx half the wasted power.

MrBee · Feb 25, 2010

My understanding, from the great folks on this site is that it would be better for your Boat Batteries to use a 12v Cig. supply instead of the inverter. That being said, i use an inverter. I chose that because I only wanted to spend ONE time and so that i could also run/charge corded and cordless tools. As to the inverter, I have a high end high power Gateway and found that If I used those 300 - 400 watt Type inverters that plug to the Cig lighter, I couldn't even use the mouse. I had to have the better output of the inverter. This works fine for me but you have to decide what your needs are.

Brian

zeehag · Feb 25, 2010

the 12 v laptop connectors are very expensive 200 dollars a piece--and last only 3-4 months--i went thru many of them before i bought a 400 wtt invertor--i tried to use it via the 12 v outlet in boat---not function--screams not enough juice-can only use that way for up to 90 wtts lol...i wired it into the boats circuitry and it works perfectly--do it this way and will work for looong time --not have to cost 200 dollars/plug lol...goood luck--i am happy with mine--i live aboard and havbe for many yrs--is the best way i have found to use lappy on board without aggravation and screaming invertors and much overhead for new 12 v plugs lol.....goood luck....btw--i felt the box on 12 v and on 120---it is warm both ways--spozed to be..just not spozed to be realllly hot.....

i tried kensington, m fuel, and hp for my hp pavilion....the hp lasted for 4 uses..lol...the kensington was 3 months and m fuel was 4 months--all from circuit city and had warantees not recognized by circuit city(after the fact , btw--) ...goood luck......

kendall · Feb 25, 2010

I agree, dual conversion is a waste of power.

Nearly anything that is designed to be portable will have a 12v adapter available. No reason to introduce more draw than needed to charge/use the device.

Only reason I would consider an inverter would be if I had a LOT of things I needed to run on 120v, and would have the draw regardless (at this time I have exactly nothing) otherwise the 12v is the way to go.

You can get power supplies for desktop computers that run off 12vdc, (roughly the same price as an AC version, and designed to fit in the same space) and many LCD monitors have 12vdc internal circuitry (often a 12vdc power supply) so using one of those, you could easily assemble a nice computer in an attractive cabinet designed to look 'right' in the boat, or that could be placed inside unused space to hide it.

Ken.

Jon M · Feb 25, 2010

Joe,
check out this site, http://www.laptoppartsnow.com/power-car.html?gcw=1&gclid=CPfNv8ySjqACFd1L5Qod0GpRgg
I checked for my laptop (HP Pavilion) and it was 45 bucks. Not bad.
I am in the process of revamping my Lancer 25's electrical system now and I was also thinking of this, but I might try a buck boost transformer from 12V to 18.5V 3.5A output, which is what my wall charger for my laptop coverts to. and then getting a new tip to plug into the computer and hard wiring it all in to the boats electrical system. Just a thought so far. I'll let you know how it goes!
Jon

kenn · Feb 25, 2010

If you're buying a computer specifically for use on the boat, try to find one where the DC input/charge voltage from the AC power supply is 12v or less, because the required 12v adaptor can be alot simpler, therefore cheaper.

I use a netbook (ASUS eee) in our boat and it powers at around 10.5 v.

Seattle Scott · Feb 25, 2010

I use a transformer ( $60 at Radioshack a few years ago that came with a bunch of plug in tips ). that plugs into the cigarett power socket and converts the 12 volts to about 16 vdc to run the 10 year old laptop. But I see now that most laptop battaries are less than 12 v, so maybe can run off of 12vd directly

BobT · Feb 25, 2010

I have purchased two 12v power supplies from shopbattery.net. They are mfr & model specific for your laptop. One for my old dell, and recently a new HP. Both in the mid $50 range. I hear the efficiency is better than inverters by a factor of 10. I don't live aboard or use them for more than a few hours a week, so can't speak to longevity, but it's definitely the way to go for my needs.

sailingdog · Feb 25, 2010

I'd point out that SeaClear II (not Seatalk II) and the US charts are all free...so if you want to pay for them, be my guest...but there is absolutely no reason to do so.

Joe said:
Gentlemen........ thanks for the feedback. I have found a source for all US charts and Seatalk II nav software. TWENTY bucks!!! www.cruisingservices.net. They also offer the entire charts/software product on stick memory($40), allowing you to run it directly without installing on your computer.... very nice if you use a net book. Hope this doesn't sound like an ad, it's not.... you guys know how I feel about people pitching their own stuff here under the guise of a satisfied customer.

Maine Sail · Feb 25, 2010

kenn said:
I use a netbook (ASUS eee) in our boat and it powers at around 10.5 v.

Kenn,

Be very careful with the eeePC's as some of them require 12V not 12.3, 14.2 or 11.6 but just a fixed 12V. Both Roger Long and I found this out the hard way.

I spent a good deal of time trying to figure this out and finally spoke with ASUS tech support. In order to hit the batt life they wanted, lots of stuff in the power path was evidently eliminated to boost efficiency. Their wall charger and car chargers put out 12V even with fluctuating incoming voltage. Targus, iGo and others do not make a charger that will work with some of the ASUS eeePC's.. I think I paid about $50.00 give or take for the ASUS brand 12V car charger..

Chuckbear · Feb 25, 2010

What you need is a DC to DC converter sold just about everywhere and it is much, much more efficient than using any type of inverter and completely adjustable for voltage, http://www.powerstream.com/dcdc.htm , Chuck

JoeWhite · Feb 25, 2010

Check your laptop's DC requirements. Most laptops require 19.5 VDC rather that 12VDC. I use a 75 Watt converter plugged into the cigarette lighter. Watch out as it will deplete your boat battery in about 3 hours.

druid · Feb 25, 2010

Chuckbear said:
What you need is a DC to DC converter sold just about everywhere and it is much, much more efficient than using any type of inverter ...

I'm not too sure about that. Modern invertors are pretty efficient, and since the easiest way to change voltage for DC is to convert to AC (or at least chop it), and change back to DC, I suspect the DC-DC converters actually have in inverter in them.

If your laptop runs on 12VDC or less, the battery is definitely the way to go. Otherwise... too close to call!

druid

sailingdog · Feb 25, 2010

Yes, a DC-to-DC power supply probably uses a high-frequency circuit to step up the voltage, but doing so is probably more efficient than the losses of an inverter combined with the losses induced by a AC-to-DC power supply.

druid said:
I'm not too sure about that. Modern invertors are pretty efficient, and since the easiest way to change voltage for DC is to convert to AC (or at least chop it), and change back to DC, I suspect the DC-DC converters actually have in inverter in them.

If your laptop runs on 12VDC or less, the battery is definitely the way to go. Otherwise... too close to call!

druid

kenn · Feb 25, 2010

Good advice

Maine Sail said:
Kenn,

Be very careful with the eeePC's as some of them require 12V not 12.3, 14.2 or 11.6 but just a fixed 12V. Both Roger Long and I found this out the hard way.

Thanks MS. I have one of the first-generation 7" screen eee's (701, 4G), and I misspoke by 1 volt; the required DC input is 9.5v @ 2.3 A (not 10.5v).

I'll make sure that my adaptor is well regulated for 9.5 v at the required current.