Laptop Power Choices

[pete harrison]

What is the best way of powering a laptop on a boat ?

 

Most boats are fitted with 12 volt DC - can this be used as a direct power supply and if so are cables available ?

 

Using a 12 volt - 240 volt inverter is an option but what size of inverter is required and how heavy would be the drain on the battery be ?

[Nickhlx]

Yes - most makes have a cigar lead charger available and would be more efficient than firing up a 3kW inverter unless it was on already.

 

They do take up 8-10 amps for the larger laptops though.

 

I would try and charge the laptop when "nothing else was running" lest any spikes get through to the laptop and harm it .. I think this is pretty unlikely, but additional "risk avoidance". Alternatively, charge it from the mains, whilst the engine is running through the inverter, as available power is then little problem.

 

 

Nick

Edited January 16, 2014 by Nickhlx

[Alan de Enfield]

My lap-top is 19v, rather than have duplicate energy losses (12v up to 220v then down to 19v) I purchased a multiple power supply that gives (from memory) 6V, 9V, 12V, 15V, 19V and 20 something volts, it is powered by EITHER a 220v supply with a normal 3 pin plug, or can be used with a cigarette lighter plug.

Multiple choice of jack plugs to fit anything.

Just choose the power supply you want (12v or 220v), dial in the output voltage you want and job done - Oh, and it has a USB for charging phones, Ipads etc.

 

If I can find the details I'll add them

 

Edit - here we go - it also gives a stabilised supply so if your engine is running it will not sent 14+ volts into your 12v laptop.

 

http://www.ebay.co.uk/itm/231049087456

Edited January 16, 2014 by Alan de Enfield

[smileypete]

Dunno if it's still the case but Dells used to have extra circuitry to try and stop you using a non Dell charger, there may or may NOT be a way around it.

 

cheers, Pete.

~smpt~

[Ex- Member]

We originally were going to use 12v all the time. I'ts not good for the lap top batteries though, they much prefer and will last longer if charged by a 240v supply and brick. This intelligently charges the batteries where as direct 12v dc is more intended as a temporary way of charging powering a laptop.

 

We have an inverter on 24/7 so charge when solar generator or engine is running & charging batteries. My new larger 17 inch HP lap top even gives a warning message if I try to use Lynns' 15 inch HP lap top brick for charging mine. Both will run from the 12v DC though, but I would only use it if 240 isn't available for any reason.

[WotEver]

Dunno if it's still the case but Dells used to have extra circuitry to try and stop you using a non Dell charger,

 

Details about how this works are shown here.

 

Cheers,

Tony

[alan_fincher]

We originally were going to use 12v all the time. I'ts not good for the lap top batteries though, they much prefer and will last longer if charged by a 240v supply and brick. This intelligently charges the batteries where as direct 12v dc is more intended as a temporary way of charging powering a laptop.

 

Sorry,

 

I simply don't think that is true.

 

The supply coming from a proper 12 volt "brick" will "look" just the same to the laptop as the supply coming from a 230V "brick".

 

19 volts DC at 5 amps, (or whatever your one takes) should be the same whether it was created from 12 volts DC or 230V AC, surely?

Dunno if it's still the case but Dells used to have extra circuitry to try and stop you using a non Dell charger, there may or may NOT be a way around it.

 

cheers, Pete.

~smpt~

 

Non Dell chargers are available that replicate a Dell one sufficiently that the Dell PC believes it is connected to the correct thing.

 

However after maybe 2 or 3 years the relevant bit of the circuitary in the one I have seems to have stopped working, because it did it fine until recently, but is now refusing to!

Edited January 16, 2014 by alan_fincher

[Nickhlx]

I agree 19 VDC is 19 VDC, whether from a 12V brick or a 240V item, but I would bet that some more expensive items also monitor current being drawn to detect state of charge of the batteries in an attempt to not damage them by overcharging, or even a signal superimposed on the DC to tell the charger to modify its output. Some 12V DC bricks may or may not have this advanced feature

 

Nick

[alan_fincher]

My lap-top is 19v, rather than have duplicate energy losses (12v up to 220v then down to 19v) I purchased a multiple power supply that gives (from memory) 6V, 9V, 12V, 15V, 19V and 20 something volts, it is powered by EITHER a 220v supply with a normal 3 pin plug, or can be used with a cigarette lighter plug.

Multiple choice of jack plugs to fit anything.

Just choose the power supply you want (12v or 220v), dial in the output voltage you want and job done - Oh, and it has a USB for charging phones, Ipads etc.

 

If I can find the details I'll add them

 

Edit - here we go - it also gives a stabilised supply so if your engine is running it will not sent 14+ volts into your 12v laptop.

 

http://www.ebay.co.uk/itm/231049087456

 

That one has a dodgy technical spec though, as it implies it can deliver 5 amps output current at a variety of voltages from 12 volts to 24 volts. However 5 amps at 24 volts would be 120 watts, whereas the description says it is 90 watts.

 

Both those can't be correct, can they?

[Alan de Enfield]

The supply coming from a proper 12 volt "brick" will "look" just the same to the laptop as the supply coming from a 230V "brick".

 

19 volts DC at 5 amps, (or whatever your one takes) should be the same whether it was created from 12 volts DC or 230V AC, surely?

 

 

I'd have thought so - 12v DC is 12v DC, its not as if there are different wave forms.

[alan_fincher]

I agree 19 VDC is 19 VDC, whether from a 12V brick or a 240V item, but I would bet that some more expensive items also monitor current being drawn to detect state of charge of the batteries in an attempt to not damage them by overcharging, or even a signal superimposed on the DC to tell the charger to modify its output. Some 12V DC bricks may or may not have this advanced feature

 

Nick

It's a theory, but can you find any source that confirms it?

[Alan de Enfield]

alan_fincher, on 16 Jan 2014 - 5:39 PM, said:

 

That one has a dodgy technical spec though, as it implies it can deliver 5 amps output current at a variety of voltages from 12 volts to 24 volts. However 5 amps at 24 volts would be 120 watts, whereas the description says it is 90 watts.

 

Both those can't be correct, can they?

 

Item specifics

 

Type: AC & DC Bundled Items: 12V Cig Lighter Cable,

Detachable Plugs,

Power Cable

Max. Output Power: 90 W

Output Voltage (s): 12 V

Output Current: 5A

Edited January 16, 2014 by Alan de Enfield

[Ex- Member]

Well I was told this by a PC world engineer as the battery in my old lap top had worn out quite quickly, I was charging it at that time on 12v that's when he said the 240v brick would charge better.

 

Lynn's lap top has always used a 240v brick and her lap top was twice the age of mine, so his explanation made sense to me.

 

ETA and both lap tops were the same as well.

Edited January 16, 2014 by Julynian

[alan_fincher]

Well I was told this by a PC world engineer

I rest my case M'lud!

[Ex- Member]

I rest my case M'lud!

 

LOL They did replace it FOC though maybe their generosity far outweighs their technical knowledge :-)

 

When my lap top battery runs down a bit I'll post the warning it gives when I plug in Lynn lap top brick.

[pete harrison]

I would like to thank everybody for their input, most of which I understand, but some of which I do not.

[Proper Job]

I use one of these

 

http://www.maplin.co.uk/p/12v-auto-voltage-carair-laptop-adapter-with-usb-socket-1a-12-charging-tips-a83la

 

...... and the 5v output is very useful for charging phone's, Ipod's and tablets

Edited January 17, 2014 by Proper Job

[Richard10002]

I use one of these

 

http://www.maplin.co.uk/p/12v-auto-voltage-carair-laptop-adapter-with-usb-socket-1a-12-charging-tips-a83la

 

...... and the 5v output is very useful for charging phone's, Ipod's and tablets

I think the auto voltage on these is actually dictated by the tip used... So if a tip fits an item that requires only 12V, but the tip causes the unit to provide 19V. I resisted buying one of these for fear of causing something to fry.

 

Maplin used to provide a table which showed a list of all the tips, along with the voltage that each tip draws.

 

I would prefer a user selectable voltage.

[Proper Job]

I think the auto voltage on these is actually dictated by the tip used... So if a tip fits an item that requires only 12V, but the tip causes the unit to provide 19V. I resisted buying one of these for fear of causing something to fry.

 

Maplin used to provide a table which showed a list of all the tips, along with the voltage that each tip draws.

 

I would prefer a user selectable voltage.

 

I wondered how they worked.

 

Maplins used to do the manually switchable ones. I had one but lent it to my daughter. It never came back.

 

I went to Maplins to get another and they sold me the auto one I'm using now. To be honest, I just blindly plugged it in with the right tip and it worked

 

I will now have to go home and get me multi meter out and check the output with the various other tips

[Alan Saunders]

Google e.g. 'car charger hp dm1' (replace 'hp dm1' with your laptop make/model) to find chargers that are specific to your laptop.

These may be more reliable than the multi-voltage ones with interchangeable tips.

 

BTW, it is more economical to run the laptop from the boat batteries via a 12v adapter than from the internal battery.

My 11.6 inch laptop averages about 1A which is not a huge demand from the boat battery (larger laptops will take more; maybe 1.5A).

It will run for ~6hr on a new 6600mAh internal battery but each charge/discharge cycle reduces the capacity.

Mine now reports that it has had 430 cycles and is down to 60%. A non-original replacement will cost me anything from £30 for a standard 4800mAh battery to £50 for a high capacity 7800mAh one.

 

Putting it another way a LI-Ion laptop battery is about £6 per Ah but a basic 110Ah lead acid battery is maybe £0.70p per Ah.

 

HTH, Alan

[Richard10002]

My lap-top is 19v, rather than have duplicate energy losses (12v up to 220v then down to 19v) I purchased a multiple power supply that gives (from memory) 6V, 9V, 12V, 15V, 19V and 20 something volts, it is powered by EITHER a 220v supply with a normal 3 pin plug, or can be used with a cigarette lighter plug.

Multiple choice of jack plugs to fit anything.

Just choose the power supply you want (12v or 220v), dial in the output voltage you want and job done - Oh, and it has a USB for charging phones, Ipads etc.

 

If I can find the details I'll add them

 

Edit - here we go - it also gives a stabilised supply so if your engine is running it will not sent 14+ volts into your 12v laptop.

 

http://www.ebay.co.uk/itm/231049087456

Amazing! I bought a Samsung TV last year, on the basis that the 240V power pack converts the voltage to 14V, and connects to the TV with a laptop type pin. The assumption was that it would probably work off 12V, so I could use a 12V power supply with an appropriate tip.

 

Anyway, having bought it, I couldn't find a 12V power supply with the right sized tip - this one does the trick, with the right sized tip, and the ability to select the voltage.

 

All plugged in, and working fine! Thank You!

[Alastair]

Are people seriously suggesting that a lithium ion battery is safe if plugged into an unregulated DC power source?

 

Some laptops will have internal regulation of the charging for the battery. Some laptops will have the regulation built into the charging brick.

 

Incorrect charging of a lithium ion battery is not safe. At the least you run the risk of destroying your laptop, at the worst you have a fire on board. All for the sake of saving a few watt hours.