Power for laptop on board

[cass123]

I realise this has been covered before- last one just a few days ago- and apologise for asking again, but for those of us where the Electricity and general magnetism paper for Masters F.G. is but a distant memory,even the simplest basics leave doubts.

I've just bought one of those CF GPS receivers to use on an old IBM thinkpad I ïnherited". I also have a portable 12v power supply/emergency start pack which is rarely used and thought I could power the thinkpad with this , after charging up the battery on shore power before leaving the marina.

There seem to be two possibilities;
Inverter 12v - 230v - 16v or.
12v converter to 14v,16v,18v etc.

Am I correct in reading from previous posts that the 12v-16v direct is the most efficient way to go ?.

Also confused by the fact that on the ;
back of the laptop gives output as 16v 3.36A
charger/house power converter gives output as 16v 4.5A
battery gives 10.8v 3.6A/hour.

Thanks to those who might have the patience to respond.

 

[fireball]

back of the laptop gives output as 16v 3.36A
This is the (max?) power consumed by the laptop - including charging the battery

charger/house power converter gives output as 16v 4.5A
This is the power output of the laptop transformer - rated slightly above the max required for the laptop - so it doesn't blow out...

battery gives 10.8v 3.6A/hour.
This is the powerout by the battery - generally what is required by the laptop....

We've got an old Tosh laptop - with a 15v transformer, the battery is kn*ckered so we tried using it just off the boat 12v supply - works a treat so no transformers needed....
Worth trying this on yours before you spend out on invertors/transformers etc etc

The older laptops seem to work off the lower voltage and the newer ones appear to be all around 19v ... typical - I'm sure this was a move to make us by more equip for mobile computing .... /forums/images/graemlins/frown.gif

 

[Evadne]

That's what I'd do as well. You rarely blow things up by not putting enough volts into them, and most equipment will run on a range around the quoted voltage (e.g. 9 to 18V = 15V) because that's what the DC-DC converter inside will run on.
Older equipment may have a linear regulator that cuts the voltage down to 12V or 15V and wastes the extra energy as heat.
If you really do need a higher (or lower) DC voltage from your batteries, DC-DC converters (see Maplins et. al.) are the most efficient way of producing it.
The battery packs on old laptops are usually made up of Ni-Cd "c"-cells, and if so are quite cheap and easy to make up yourself, if you buy tagged cells.

 

[Guest]

Answers as I see from actually using !!

a) DC - DC is best .... then you don't have power loss converting 12v - 240 - 16 ..... (its a cheaper unit as well !! 29.99 in Maplins ....) It fits the IBM ok - as I use mine on an IBM .... in fact I use the same connector as with my ACER which is the 18V one .... no harm at all.
b) Battery is less as you need i. power for computer ii. power to charge battery .... add the lot up = power from supply.
c) Power pack is fine .... friend of mine gets basically a good days use out of the pack - and its only a Macro special job - not the luxury job !! You can always charge it of the engine as well / run computer etc.

Magnetism ....... FG .............. blimey - bring back the memories !!!

Finally go for it - you will wonder what the hell you did before !!! AND join the GPS Nav group - FOR ALL questions / answers etc .....

http://groups.yahoo.com/group/gps-navigator/

 

[Colvic Watson]

Just a few ideas from a non-scientist:

1. Modern inverters loose only 10% current but only the expensive ones have a 'pure' sine wave - an old lap top may not like the simulated sine wave output from an inverter - check with IBM.

2. The DC current converter you mention will be the cheapest option, but an inverter can be used for other electrical appliances.

3. Lap tops use (relatively) vast quantities of power - they spew out heat and the screens are incredibly inefficient - watch the current drain!

We use a £50 inverter from PC world and it powers either laptop we take just fine. Also powers other bits and pieces.

 

[Guest]

12V direct connection ...

I have done this with Tosh, IBM Thinkpads, Acer, Maxdata, Twinhead, and other NB's I have had over the years ... never worried about the lable on back ... ALL worked ok - but the charge LED always blinked as charging - but no charge went in. The trick of taping over of battery contacts works and sorts the power to the NB ... well it did for me. Leaving the battery in place keeps the whole thing balanced.

You will hear all sorts of horror stories about power consumption etc .... As my mate did - he set up at home and let it run till it stopped literally ........... now he's a devoted GPS man !!

 

[Swagman]

Re: 12V direct connection ...

Back up last post - most laptops run on 11/12 v anyway - they prefer 18/19 v input in order to charge the battery therein. If you are not worried about charging and happy to leave it connected to power when in use - 12v DC works fine.

 

[davidbains]

Re: 12V direct connection ...

You're quite right. We had terrible trouble charging a 19volt Tosh with a huge
screen last summer. A small inverter wouldn't do it and we couldn't
get a DC/DC converter powerful enough. It needed 19v 6.3amps!
Just taken the battery out and it's 14.5volts !! Still 6amps tho!
Must try it direct to the ships battery.
David.
Mainly used by my family to watch DVD"s.
I use a small 12" I Book for nav, running on a 12/24 converter.
A really tough little notebook.

 

[William_H]

Re: 12V direct connection ...

Now for an absurd idea. If it needs 15 to 16 volts to run you could get some NiCad or even lead acid cells to put in series with the ships supply. So 2 NiCad or NiMh cells will add 2.5 volts to give you about 14.5 volts sailing or 16.5 volts motoring. 3 cells will give you 15.75 volts sailing or nearly 18 volts motoring. One lead acid cell gives about 2 volts additional voltage. You need big cells if we are talking 3 amp drain so new 9 AH NiH D cells will give maybe 2.5 hours. if you had one of those car batteries with exposed cell joiners (or am I showing my age) then 2 ,4 or 6 volts could be tapped off. Maybe you could find an old 6 v VW battery but beware of the voltage rise when engine is charging. Obviously cells or batteries would need to be charged when disconnected. One caution if NiCad or NiMh cells go to zero volts and you continue to use them in series with the ships battery they will tend to charge in reverse polarity which they do not like so watch their voltage. regards will

 

[duke]

Hi All,

I recently posted a question on this site about powering a laptop from either onboard 12V or 24V supply and got advice including referrals to Maplin and laptopshop.co.uk.

The laptop is a Dell inspiron 1150 as follows:

mains adaptor 19.5V 3.34A
laptop 19.5V 4.62A max
battery 14.8V 4300 mAH


I couldn't find any 19.5 V adaptors on either Maplin site or Laptopshop so I phoned Maplin. The salesman I talked to seemed very knowledgeable and warned against using anything different than exactly 19.5V.

He said that 19V adaptors (which they have) may work for a while but because the internal components of the laptop would constantly be searching for the 19.5V that my laptop requires, that within a matter of hours/days the laptop would be damaged and become inoperable.
He also said that up to recently Maplins did sell a 19.5V adaptor but they no longer listed them. He mentioned their name as "Juice / IGO".

I had also sent an email enquiry to Laptopshop and they have now replied that
they have 12 volt adaptors (quote) "which are suitable for most computers so should do the trick, however we have found that customers have reported sometimes on boats the voltage is not stable enough and so keeps tripping the over voltage sensors on the adaptors" (unquote).

Laptopshop also referred me to their online site calculator where one can input your laptop voltage and amps and get your "watts" ; for instance I put in 19.5V
3.34A and got a figure of 65 watts.
Laptopshop offer either an 70 watt or 90 watt adaptor and advise that if your requirements are lower than whichever one you choose, your laptop will not be damaged.

If anyone has got to the end of this rather long post, I would very much appreciate
any advice or comments.

Thanks,

Duke.

 

[Guest]

My answer ....

I really do not understand Maplins reply .... the item is called :

ENERGY KNIGHT a 12V to variable output Notebook Computer supply. It caters for 15V up to 24V by changing the spade shunt .... and has various connectors to fit PC's.

I have one and never had any trouble. It's now about a year old and used on Tosh, IBM, Acer, HP, Maxdata ......

????? As to exact voltage .... humbug I say !! I've run all the above on the 18V spade without trouble ..... OK - maybe I'm lucky ..... /forums/images/graemlins/smirk.gif

 

[Guest]

And this ...... from Maplins

http://www.maplin.co.uk/Search.aspx?Menu...2&worldid=4 /forums/images/graemlins/confused.gif

So what is the guy talking about ?????

 

[Oldhand]

From the figures you are quoting it sounds like you have an IBM ThinkPad.

Get a DC converter from here:

http://www.primepc.co.uk/index/html/cm_id/1057/action/product_detail/p_id/14129

and set it to 16volts output.

 

[duke]

Re: My answer ....

Luther,

thanks for that -reassuring!

Duke.