Laptop power from boat batteries

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saltyrob

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Hia,

I have an ordinary laptop which is 240 v/ 10.8 v battery powered .Is it practical to and if so what is the best way of running the laptop off the 12 V boat batteries.

Many thanks

Rob

P.s I may not be able to reply for a day or two but most grateful for advice.
 
Have a search for a 12V "car adapter" for your specific laptop.
They tend to be a little more efficient than big boxy inverters. There is more power lost going up to 240v - and then back to 10.8V (or what your laptop normally uses). DC/DC car adapters are neater & quieter too..

Graeme
 
Buy a charger for your computer to run off a car cigarette lighter socket (or whatever they call them these days). That's assuming you have such a socket on your boat. If not, I fitted one, and if I can do it, anyone can. Used my laptop as a plotter for two years including Plymouth-Scotland and Plymouth-South Brittany. It draws 1.7 amps. Sorry no idea where I got my charger from, it was three years ago.

You also need to think about fixing the laptop in place, there has been at least on thread on this in the past.

Just beaten to it by Pagoda-agree about inverters.

HTH
 
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iGo do some very neat chargers. Any input voltage AC or DC and output to DC of your choice. All done by having different tips.

Maddeningly they don't do one for my boat's Panasonic Toughbook. So I have to use a power hungry inverter to change the boat's DC to AC then the computer's charger turns it back to DC. Taking the laptop's battery out reduces the power requirement, but the computer dies when I start the engine.
 
Just received in today's post a Laptop adaptor which plus into the cigarette car socket. It has a variable output 15,16,18,19,20,22, and 24DC volts; my laptop works on 19v; however, you can have them with various voltage output to suit.

It will be more efficient than using my 1000w inverter. Look at the ebay; they are cheap.
 
saltyrob said:
I have an ordinary laptop which is 240 v/ 10.8 v battery powered .Is it practical to and if so what is the best way of running the laptop off the 12 V boat batteries.
Click to expand...

What make and model of laptop? The Maplin type 12v chargers, with their variety of connector tips, fit many laptops, but there are a few with proprietary type connectors. I had a Toshiba Qosmio which had a hexagonal connector with irregular length sides. I think some Dells have hexagonal connectors with regular length sides.

My Samsung Netbook and laptop are OK with the Maplin type charger.
 
+1 for what make and model. I had a DELL once and the power supply died. I bought a 'generic' one which did not work because although the DC plug looked the same the DELL had an aditional pin to tell the laptop a PSU was connected and to accept a charge.

My Acer netbook charges it's 19V battery very well with a 12V cigar plug charger bought from ebay H.K. for about £5.

As you may already appreaciate it's more efficient to use a 12V charger than an invertor whcih takes the 12V available and ups it to 240 for the normal charger to be used.
 
You don't necessarily need an inverter.

The nominal voltage of Li-Ion cells is frequently given as 3.6V, therefore a battery described as being '10.8V' will contain 3x Lithium cells.

Now such a Li-Ion battery when fully-charged will actually be 12.6V, as each cell is charged to 4.2V

So it is theoretically possible to run such a laptop directly from a 12V (14V max) lead-acid battery, providing steps are taken to protect the laptop from voltage spikes which may occur during charging, and perhaps drop a volt or two with diodes.

I run my IBM Thinkpads this way, but much depends on what make and model of laptop you have.
 
Maplins, nor anyone else it seems, have an adapter that fits the socket of my HP laptop. It's around 8 mm diameter with a small centre pin. I use an inverter, which I also need for video camera and a few other devices, so no big problem. Plenty of power from solar panels.
 
Problem with a lot of 'car adaptor' type chargers is they are stupidly designed to work off 12 to 14.5v ie what a car has when its running, or has just been running.

When on a boat the battery drops to about 11v )or even lower at the socket due to bad contacts and miles of too thin wires), these stupid things don't work. I have seen fully regulated 10-14v to 240v inverters for sale but very expensive. and as said, full inverter + power adapter is a very inefficient thing to do.

Then also, as I found to my cost, if you have bad contacts on your battery manager/alternator connectors, the alternator suddenly whacks out 18v which could boil your batteries in time, but instantly fries your laptop car adaptor, and the navtex (no loss there!)
 
+1 for Maplin car chargers. I have used them over the years for five different laptops. Only one of them had a socket for which Maplin had no connector. I created one by hacking the plug off a mains charger and soldering it on to a socket for whiich I did have a Maplin plug.

If in doubt, take the computer and its mains charger with you to Maplins and get one of their geeks to sort you out.

This topic has been well rehearsed over the months/years - there are probably 20 threads and 50 opinions. Everyone who has reported measured current has found this DC to DC solution more power economical than an inverter to mains charger. The maximum saving I recall being reported was a factor of three. The best I myself have seen was 50%, the worst 30%.

Theorists have argued that there is no intrinsic reason why the inverter solution should be less efficient, but as far as I can recall no-one on the forums has reported empirical data which supports this (which doesn't make it untrue).
 
billcowan said:
Problem with a lot of 'car adaptor' type chargers is they are stupidly designed to work off 12 to 14.5v ie what a car has when its running, or has just been running.

When on a boat the battery drops to about 11v )or even lower at the socket due to bad contacts and miles of too thin wires), these stupid things don't work. I have seen fully regulated 10-14v to 240v inverters for sale but very expensive. and as said, full inverter + power adapter is a very inefficient thing to do.

Then also, as I found to my cost, if you have bad contacts on your battery manager/alternator connectors, the alternator suddenly whacks out 18v which could boil your batteries in time, but instantly fries your laptop car adaptor, and the navtex (no loss there!)
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Maybe I'm just lucky - been using these gizmos for ten years with sundry laptops and the usual run of power/charging cock-ups. I've never had a problem keeping the computers running. The only time I had a laptop give up it was being powered through an inverter. Its internal power supply gave up. I struggle for an explanation, and have concluded it was probably coincidence.
 
pieter2 said:
Take off the battery of the lap top. The laptop will try to load the battery at all times. Without a battery they will take much less power.
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My experience is that once the laptop battery is charged it takes no noticeable extra power if it's in there (and why should it?). It's a handy reserve if you want to pass the laptop round without the hassle of wires. It's true that charging a flat laptop battery and running the laptop at the same time will eat up more amps, but usually I keep it pretty near fully charged.
 
Amulet said:
My experience is that once the laptop battery is charged it takes no noticeable extra power if it's in there (and why should it?). It's a handy reserve if you want to pass the laptop round without the hassle of wires. It's true that charging a flat laptop battery and running the laptop at the same time will eat up more amps, but usually I keep it pretty near fully charged.
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Leaving the laptop battery installed if you're powering from an external source is a very bad idea. Li-Ion batteries are designed to operate in defined cycles: run them down to a specified level, and only then re-charge them.
But if you keep 'topping them up' from an external power source, their working life will be reduced significantly.
 
Maplins car plug in thingys.

Be careful with these items as when the battery voltage drops to a certain level the convertor starts to pull more amps to keep the output voltage to the required level. The converter heats up to a worrying level so do not leave them unattended. This is not surprising as my little Samsung laptop pulls seventy watts and my outboard only produces forty eight watts flat out. Not the speed used on the Thames so my input at cruising speed is only about twenty four watts or less. In my experience, a full day's cruising (around four or five hours) equals about an hour on the computer or less if other equipment is used ie nav lights.

The moral of the story is small boatowners beware.

Regards.

Alan.
 
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electrosys said:
Leaving the laptop battery installed if you're powering from an external source is a very bad idea. Li-Ion batteries are designed to operate in defined cycles: run them down to a specified level, and only then re-charge them.
But if you keep 'topping them up' from an external power source, their working life will be reduced significantly.
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Interesting - the manual which came with my computer and a leaflet which came with a spare battery (Li-Ion) both said that battery life will be best if they are kept charged and that the computer should be on mains charge if available with the battery in. It says that they have no memory effect and the main determinant of life is charge cycling, best avoided by keeping them charged. In a conversation the supplier said that the very worst was cycling at high temperature, which is also in contradiction of forum wisdom in a previous thread. I now don't know who to believe, but for the last two laptops I have used them plugged in whenever possible and am still getting 3 hour battery life after several years and an "excellent" rating on the auto battery health-check (whatever that does!). I guess I may be doing the wrong thing, but nonetheless I have no complaints whatsoever about the performance.
 
vyv_cox said:
Maplins, nor anyone else it seems, have an adapter that fits the socket of my HP laptop. It's around 8 mm diameter with a small centre pin. I use an inverter, which I also need for video camera and a few other devices, so no big problem. Plenty of power from solar panels.
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Vyv, A few of the car chargers which come with an assortment of tips DO include the rather obscure HP 7.8mm plug with inset centre-pin. (the plugs can also be sourced online). HOWEVER they are still unlikely to work as supplied! ... Many HPs (I have an NC6400 business model) require a 'sense' voltage on the centre-pin. A 120k resistor from the +ve side of the jack to the centre-pin is all that is needed.
 
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