Gelmaster
Well-Known Member
Can anyone tell me off hand how many watts the average laptop uses?
I have just seen the "merlin inverter 1400w" for sale at £449.
I have just seen the "merlin inverter 1400w" for sale at £449.
Laptop power ?
- Thread starter Gelmaster
- Start date
sailorman
Well-Known Member
it would be much cheaper to buy a 12> whatever voltage charger
http://www.ebay.co.uk/itm/Dell-Insp...Accessories_PowerSupplies&hash=item3f0cbd7887
this chap delivered in under 2 days @ £11.95 some £5 cheaper than amazon
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pvb
Well-Known Member
The cheapest and easiest way to power a laptop onboard is via a car adaptor - typically around £20.
Laptops only use around 100w.
NickRobinson
Well-Known Member
Hi
My full size Dell uses 2 amps so under 30w when charging.
I have a Belkin 12v charger, bought to advice here that my 150w mains inverter was inefficient.
As it happens, the current draw is about the same on both methods.
(Inverter cost 14 pounds..)
Nick
My full size Dell uses 2 amps so under 30w when charging.
I have a Belkin 12v charger, bought to advice here that my 150w mains inverter was inefficient.
As it happens, the current draw is about the same on both methods.
(Inverter cost 14 pounds..)
Nick
noelex
Well-Known Member
Most laptop power supplies use from 70-140w. You need a bit more capacity to allow for inrush currents, but 1400w is more than you need.
As inverters become larger they become less efficient at lower wattages so there is an advantage in sizing the inverter correctly, although you may need the inverter to also supply other loads.
A 1400W inverter will draw about 130A @ 12v so you need a large battery bank if you want to supply the inverter at its maximum. If powering the laptop only it will only draw 12A and with a fully charged laptop battery probably about 5-6A
As other have said a 12v DC converter is more efficient (about 20% less power) and will be cheaper, but will only power the laptop, nothing else.
If you live at anchor the efficiency of a DC to DC converter is a must, but if you can plug into shore power often to charge the batteries, an inverter gives greater versatility.
Purchasing both a DC converter and inverter gives you the best of both worlds and adds redundancy always a good thing if the laptop is vital.
If you buy a smaller inverter with the money left over you can but a DC to DC converter for the laptop. That may be your best solution. You will be able to charge camera batteries etc with the inverter and run the laptop with the most effecint DC to DC converter. Small inverters are much cheaper than larger ones.
As inverters become larger they become less efficient at lower wattages so there is an advantage in sizing the inverter correctly, although you may need the inverter to also supply other loads.
A 1400W inverter will draw about 130A @ 12v so you need a large battery bank if you want to supply the inverter at its maximum. If powering the laptop only it will only draw 12A and with a fully charged laptop battery probably about 5-6A
As other have said a 12v DC converter is more efficient (about 20% less power) and will be cheaper, but will only power the laptop, nothing else.
If you live at anchor the efficiency of a DC to DC converter is a must, but if you can plug into shore power often to charge the batteries, an inverter gives greater versatility.
Purchasing both a DC converter and inverter gives you the best of both worlds and adds redundancy always a good thing if the laptop is vital.
If you buy a smaller inverter with the money left over you can but a DC to DC converter for the laptop. That may be your best solution. You will be able to charge camera batteries etc with the inverter and run the laptop with the most effecint DC to DC converter. Small inverters are much cheaper than larger ones.
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agurney
Well-Known Member
Having fried a couple of adapters recently I tried this one from Maplins:
http://www.maplin.co.uk/150w-laptop-car-adaptor-223723
It works fine for my HP netbook, but I cn't use it to charge my works Dell laptop at the same time as using the screen without it overheating.
My 150W inverter doesn't cope with the laptop's 140W power supply
http://www.maplin.co.uk/150w-laptop-car-adaptor-223723
It works fine for my HP netbook, but I cn't use it to charge my works Dell laptop at the same time as using the screen without it overheating.
My 150W inverter doesn't cope with the laptop's 140W power supply
Heckler
Well-Known Member
Mine that Im typing on has a 19v 3.25 amps charger or 240v 1.5amps
Stu
sailorman
Well-Known Member
Having fried a couple of adapters recently I tried this one from Maplins:
http://www.maplin.co.uk/150w-laptop-car-adaptor-223723
It works fine for my HP netbook, but I cn't use it to charge my works Dell laptop at the same time as using the screen without it overheating.
My 150W inverter doesn't cope with the laptop's 140W power supply
34 squids
mine was under £12 delivered in 2 days
agurney
Well-Known Member
34 squids
mine was under £12 delivered in 2 days
So was the one I had that melted.
TQA
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As others have said if the only thing you are running that needs an inverter get a 12 volt car adapter.
Some can only JUST supply enough current to run a lappie in a high performance mode so keep an eye on the battery level and switch to a lower performance mode if needs be.
I am running a PWR+ just now and the consumption is significantly less than running the Toshibe power suply off a 100W inverter.
Some can only JUST supply enough current to run a lappie in a high performance mode so keep an eye on the battery level and switch to a lower performance mode if needs be.
I am running a PWR+ just now and the consumption is significantly less than running the Toshibe power suply off a 100W inverter.
Csail
N/A
Having fried a couple of adapters recently I tried this one from Maplins:
http://www.maplin.co.uk/150w-laptop-car-adaptor-223723
It works fine for my HP netbook, but I cn't use it to charge my works Dell laptop at the same time as using the screen without it overheating.
My 150W inverter doesn't cope with the laptop's 140W power supply
Second that comment.
nimbusgb
Well-Known Member
A 1400 watt inverter will probably draw more power doing nothing than a 12v to laptop converter will actually float charging the laptop.
sailorman
Well-Known Member
NickRobinson
Well-Known Member
So far I'm the only poster who's offered quantitative (if not definitive) info..
Come on, others, have you tried different systems and recorded the amps?
Dockhead
Well-Known Member
For laptops and phones, 12v power supplies are logical, cheap, simple. They must logically be more power efficient, but this is not even the main consideration.
For a rarely used television, the sense of hacking together a 12v power supply is questionable -- it's theoretically better, but I haven't seen the practical worthwhileness and have not done it. In the past, I have used an el cheapo (8 pounds) Taiwanese 150watt inverter to power the tv and dvd player, which supposedly need 210 watts between them. Got hot but worked fine for hours of cinematic pleasure.
Since we installed a Victron charger/inverter this summer, I just put that on. It's somewhat inefficient for driving 210 watts but am I going to install another, smaller inverter just to save a couple of watts on the rare occasion when I watch a movie at anchor? No.
For a rarely used television, the sense of hacking together a 12v power supply is questionable -- it's theoretically better, but I haven't seen the practical worthwhileness and have not done it. In the past, I have used an el cheapo (8 pounds) Taiwanese 150watt inverter to power the tv and dvd player, which supposedly need 210 watts between them. Got hot but worked fine for hours of cinematic pleasure.
Since we installed a Victron charger/inverter this summer, I just put that on. It's somewhat inefficient for driving 210 watts but am I going to install another, smaller inverter just to save a couple of watts on the rare occasion when I watch a movie at anchor? No.
Amulet
Well-Known Member
See: this thread, this thread, this thread, this thread and this thread for more discussion of this topic.
[I mean to be helpful, not snotty.]
Amulet
Well-Known Member
Course I didn't provide any answer to the question you asked!
My normal AC laptop charger says:
Output:
19 volts, 4.7 amps
that gives 91.65 watts
if I did a zero loss transformation from 12 volts that'd be 7.64 amps
Actually, with the battery fully charged so that it is running the computer but not having to put power into the battery I see a drain of about 2.5 amps. (I run a lean regime on the computer - stop disks, dim screen etc.). If it is charging the battery and running the computer it can go to 7 amps. All this using a Maplin car charger to convert from 12 volts to 19. I saw about twice the consumption with an inverter.
On the AC computer charger it says:
Input 240 volts, 1.5 amps = 360 VA
Which is a helluva lot to generate 91.65 watts on the DC side, even allowing for the fact that it is an inductive AC load!
noelex
Well-Known Member
Its unusual for th 12V alternative not to be more efficient. Usually 20-30% less power. The lithium batteries in laptops need a variable supply current depending on the state of charge, so if you are comparing the consumption when charging you need to measure the input with the same level of charge.
I am not sure if you mean 2 amps when the laptop is running, or shut down and just charging it is low for figure for a 15 inch laptop if you mean the former, but they are getting better.
My figure for a fully charged battery plugged into 12.6V at full screen brigness with average processor speed are:
Older 15 inch IBM T60P 3.0 A
MSI netbook 1.0 A
With a flat battery and running the T60P draws about 5 amps.
nimbusgb
Well-Known Member
Samsung NC10 - completely flat battery - Amazon 'samsung' 12v/19v converter. 3.7 Amps. once fully charged it draws about 800ma depending on screen brightness and what the laptop is doing at the time.
150w Maplin inverter, no load - 200 ma ! using the Samsung mains adaptor 5.3 amps.
1500w pure sinewave inverter - no load - 1.2 amps
Bav32
Well-Known Member
Another thumbs up for the Maplin device. I,ve used mine to power and rechage an old HP laptop.
The ability to chose the output voltage and the adaptors provided make it a very versatile bit of kit.
I would only go down the inverter route as a last resort.
They are VERY inefficient re the power in to the power output and trust me you don't want to see what the outputs look like on an oscilliscope. VERY few produce a good sine wave; most of the cheap ones create lots of potentially troublesome harmonics which can cause PC's and the like to corrupt data etc.
The ability to chose the output voltage and the adaptors provided make it a very versatile bit of kit.
I would only go down the inverter route as a last resort.
They are VERY inefficient re the power in to the power output and trust me you don't want to see what the outputs look like on an oscilliscope. VERY few produce a good sine wave; most of the cheap ones create lots of potentially troublesome harmonics which can cause PC's and the like to corrupt data etc.