Laptop charging systems

[minrags]

I am looking for new ways to power my laptop. I currently run it on its original battery, using an inverter to convert the power from the boat ‘house’ battery. The laptop is used a lot during the evenings when the engine is not running and so causes the house battery to drain quickly. Has anyone come up with any ideas on how to power a laptop without running the house batteries down. I thought about buying a separate Gel battery for the laptop only, but how would I connect the Gel battery to the laptop and would there be any risks? If anyone has an good ideas please reply. Thankyou

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[bendyone]

Hi I use a aircraft type power unit to run a laptop. This converts 12v to 20 V DC. It is more effecent that running a normal charger through an invertor. I brought a Dell unit off ebay for £20.00 cut the Dell end off and fitter the right connector for my laptop.

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[qsiv]

Targus do a neat system - different plugs 'signal' the PSU, telling it what volts and amps are required (as well as fitting to your laptop)

Try <A target="_blank" HREF=http://www.targus.com/uk/accessories_power.asp>here</A>

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[Talbot]

even using these ideas, you are still going to be using 6-8amps/hr with the conventional modern laptop. Your post does not say what you are using the laptop for. Solution to your problem will depend on your useage. If you need the full power of a modern laptop, then you are very limited in your options.
The following options are in a reducing laptop capability table:

Using the dc converters is the first stage (Maplin have similar available).

Use a less modern laptop e.g. a 200-400 chip will use far less power, but can still do most of the laptop functions (but not processor hungry applications or DVDs)

get a small computer (such as Fujitsu 5000 - yes I know they are only sold in USA or far east, but check them out) These have a small display approx 10", but their batteries are good for 3 times that of a 2.4Gb laptop.

If your useage can be carried out on a smaller device, get a PDA, they will last much longer.

Alternatively buy a generator (wind or petrol/diesel)


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[jimi]

I'm running an oldish Toshiba straight from the domestic batteries.

<hr width=100% size=1>O wad some Power the giftie gie us
To see oursels as ithers see us!

 

[robind]

Have you thought of using one of these emergency "engine starting power-packs" as a prime use battery?and charging it on the way home or when the engine is running. Just a thought

Rob

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[Talbot]

How large is your inverter?

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[jimi]

Ain't got an inverter, just cut the wire from the transformer to the Tosh and wired it straight to the domestics. Seems to work OK.

<hr width=100% size=1>O wad some Power the giftie gie us
To see oursels as ithers see us!

 

[Guest]

Direct or not direct ....

It is possible to run the notebook direct from the domestic ..... but you will normally find that it will not charge or the LED shows bad charging.
If you have an older notebook that you don't mind doing it to ... take out the battery pack and run it without ..... Yes I know they tell you not to do it, I believe this is because the battery is a stabiliser and also takes off the excess power supplied from the normal charger ...... as most notebook chargers are 16V up to 20V depending on model / maker.

It is common that the actual notebook runs on 12v dropping to 5v or 3.3v across the board. So direct wiring has no problem. It is as well not to have it connected though when starting the engine ....... once engine started it should be OK .....

I run an old Twinhead mono 486 this way ... lasted years and still going !! I tried it on the company Tosh P11 ..... no problem !!

<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
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[poggy]

Hi,

Not sure what laptop your running, but most laptops would be around 3 amps max and this includes running the laptop and charging the internal batteru. More modern PC's can actually use less power as the design and chips are more efficient, but this of course depends on how old the laptop is.

I would look for the 12v adapter for the PC, there are a few places which sell them. If you are worried about battery usage, don't use a 12V to 240V invertor as they do introduce power losses.

Poggy



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[Talbot]

I suggest you re-visit either your laptop charger or your maths. My figures are taken directly from the charge packs of a 2.4GhZ P4 , a 336MHz and a 200MHz laptop. The figures for the 200 and 336 are the same (although of course the 200 battery lasts longer). The figures are thus:

2.4 GHz 19v at 4740 mA equates to 7.5 amps at 12v

200/336 18v at 2.5amps equates to 3.75 amp at 12 v

(dont forget that a mA is one thousandth of an amp)

I rest my case!!!!!!!!!!!!!!!!!!!

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[Talbot]

The advantage of the inverter is that you are not providing too high a power when the engine is charging, however if your laptop is running at 18-19v this should not be a problem. I would expect that the laptop is using all the power, and thus not able to divert any to the batteries, it may even be that it is actually using some battery power as well, but my tech knowledge not sufficient to be able to speak about an unknown laptop!

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[poggy]

Hi,

Last time I checked my maths were pretty good as I did a degree in Physics and electronics. We also run a company developing products for outside broadcasts, i.e using batteries. Your 2.4Ghz PC would be incredibly inefficient if the power consumption is this high. If you are taking this figure from the charger unit supplied with the unit then you need to remember these figues include charging the battery and also include a fair amount of excess capacity. The charger pack bears little relation to the power used, it is the maximum the power supply can handle.

Just because a charger pack states it's maximum capacity, it will not always be delivering this amount. Take your boat battery charger, it may start at 10A, but will drop to around 1 amp when the battery charges.

I am afraid this is a common mistake. Check your battery pack and if your computer can last 90 minutes, which is a common time, I doubt you have a 10amp battery in it.

I suggest you use a meter and measure the cosumption on a meter.

Poggy

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[jimi]

Its an old Toshiba Satellite Pro with the adapter output rated at 15V 3A. Thought the domestics were close enough;-)

<hr width=100% size=1>O wad some Power the giftie gie us
To see oursels as ithers see us!

 

[poggy]

Hi,

If your PC allows you to do so, remove the battery as it will save on power even if it was fully charged. It will also make the battery last longer than plugging it in and out all the time on partial chargers. If you find that you battery doesn't always fully charge, see if the manufacture has a battery calibration program to re-set the charge indicator. I know makes such as Advent (PC World) have these.

I often remove my battery when I am plugged in.

Poggy

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[Talbot]

I would have thought so too!

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[Robin]

All the discussion below really illustrates why on a sailboat at least it is better to use a dedicated chart plotter rather than a laptop for navigation. 24hrs @ 3A = 72AH. We run a 10" B&W plotter on 18AH/24hrs and a 5" waterproof colour one in the cockpit on 12AH/24hrs. Assuming for a laptop 72AH over 24hrs you would need a (min) 144AH battery just to supply this, nothing else, and not discharge more than 50%, the recommended maximum.

Laptops are useful on board, we use one (intermittently) for weatherfax, RTTY weather as well as passage planning. However the intermittent usage is low enough to run on the internal battery between opportunities to recharge either via shorepower or the inverter when the engine is running.

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[jimi]

Och I thinnk your analysis is in fact flawed. You are making the assumption that the laptop is consuming 3A continuously .. its not, in fact a lot of the time like any good YM it is sleeping until called into aaction and consuming virtually nothing, however the Chartplotter is on all the time so in fact if you carried out an actual time & energy study, you may find there is sod all difference in energy requirements .. forgive my language and accent ... a momentary lapse I can assure you!

<hr width=100% size=1>O wad some Power the giftie gie us
To see oursels as ithers see us!

 

[poggy]

Hi,

Too true, the plotters are designed for one purpose and so there should be less wasted power on things which you don't need or use.

Someone suggested a power pack, these are actually a really good source of power and are isolated so no risk of discharging batteries on board. I have one which is about 18Ah. Makro sell them for about £18+Vat sometimes.

Poggy



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[poggy]

Hi,

This is also true, especially if you don't charge the battery, but if you a GSP card etc then power consumption is increased even in sleep mode as it will still track position if you are using plotting software. You can save a lot on the screen though when the backlight tubes are off.

Poggy

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