Inverter for laptop

[Starcoaster]

My laptop is apparently allergic to being run on the boat's 12v, and bizarrely after my prior thread saying that this is only the case on my own boat, it has started to spack out on Reg when on the 12v for any length of time as well. It never used to do this, but meh!

 

One of the options/the least hassle option MB has suggested to deal with charging and powering it is to get a small plug and play inverter to power the laptop on 240v.

I don't have an inverter at all currently and will only want it solely to run the laptop, so I am looking to get the cheapest, most basic option available.

 

I can't work out if I will need a PSW inverter or not- anyone? Also I assume a 100w one will be fine, I think that is the smallest available?

 

Am I missing anything obvious, or are there any flaws in my plan? Because I am not clear on why, when the laptop doesn't like the 12v supply, it will be ok with a 240v supply that is actually firstly coming out of a 12v socket. But I don't need to be clear on it as long as iit will work!

[DeanS]

Hi Star.

 

Maplin sell small invertors.

You don't need a pure sine wave...It should cost you around £25 or close I think.

 

 

eta....I cant actually see invertors on their web page, but a friend got a 1000W one from them..and I'm sure they've had smaller ones before..maybe phone them to check

Edited September 26, 2013 by DeanS

[ditchcrawler]

Maybe the Ciggi plug on the laptop charger is slightly faulty, may have overheated or poor contact in the socket

[matty40s]

I would get a PSW, if your lappy doesn't like strange electric, it's best to give it nice wavy electric.

[alan_fincher]

An 100W inverter may well be fine, but be aware different laptops take very different amounts of power.

 

My chunky Dell with a large screen actually has a power supply rated at 130 watts. It is doubtful it draws anything like that very often, but if it is both trying to run, and recharge its internal batteries, I would not be certain it would run faultlessly on a 100 watt inverter.

 

See what the power rating of your mains "brick" is, and don't buy an inverter that is less.

 

You certainly can use just a basic MSW inverter - you don't need pure sine. You may find that a 300 watt (say) inverter doesn't cost much more than a smaller one, and it would give you a bit more flexibility if you want ultimately to run other things from it.

 

An inverter is only as good as the cabling connecting it to the battery bank. If that is not able to handle the currents involved without significant wolts drop, then you may just replace one thing that is unreliable with another!

 

EDITED: Should have said 130 watts.

Edited September 26, 2013 by alan_fincher

[Starcoaster]

I've tried with several different types of chargers and they all react the same way. MB also changed the socket, but this didn't fix it!

I would like to establish if I definitely need PSW as the price difference between PSW and modified is large. also, if 100w is ok, or I need more? Googling seems to state that received wisdom is you don't need a PSW one.

But some of the inverters I am viewing say they are not suitable for protracted use, and the laptop will be in use about 10 hours a day; are modified ones not good for prolonged use, or is it just because I'm looking at the cheaper end of the scale ones?

 

**Edit. Alan, which bit of info on the brick gives me the power rating? I can't see anything mentioned in watts.

I need to establish if it is to do with the wiring to the socket, as this is the kind of thing I was worried about as getting an inverter seemed too simple... How do I do that ?

Edited September 26, 2013 by Starcoaster

[alan_fincher]

I would get a PSW, if your lappy doesn't like strange electric, it's best to give it nice wavy electric.

 

A PSW will cost a lot more, and I believe not required. If I can work out how to get it to Starry, I'd be happy to lend an MSW one to prove it will do the trick.

[DeanS]

I've tried with several different types of chargers and they all react the same way. MB also changed the socket, but this didn't fix it!

I would like to establish if I definitely need PSW as the price difference between PSW and modified is large. also, if 100w is ok, or I need more? Googling seems to state that received wisdom is you don't need a PSW one.

But some of the inverters I am viewing say they are not suitable for protracted use, and the laptop will be in use about 10 hours a day; are modified ones not good for prolonged use, or is it just because I'm looking at the cheaper end of the scale ones?

 

**Edit. Alan, which bit of info on the brick gives me the power rating? I can't see anything mentioned in watts.

I need to establish if it is to do with the wiring to the socket, as this is the kind of thing I was worried about as getting an inverter seemed too simple... How do I do that ?

 

Star, we have 2 laptops, and a tv on 24x7 . We have a cheap Chinese Modified Sine Wave invertor. It's a big one,but the laptops are fine.

 

eta...the price difference between a 100Watt and 300Watt is probably not much, so I'd suggest you go for a 300Watt

Edited September 26, 2013 by DeanS

[alan_fincher]

 

But some of the inverters I am viewing say they are not suitable for protraccted use, and the laptop will be in use about 10 hours a day; are modified ones not good for prolonged use, or is it just because I'm looking at the cheaper end of the scale ones?

Some inverter ratings quoted are peak use, and if you dig deep they actually have a lower rating for continuous use. Don't know if that applies to small ones, but it is possible a cheapie is rated at 100w, but only good for 80w continuous.

 

Tell us exactly what is written on your mains "brick"

 

Example from mine....

 

Input 100-240V ~ 2.5A

Output 19.5V = 6.7A

 

What does yours say.

 

The key point here is that 19.5 volts times 6.7 amps implies the power supply can deliver just over 130 watts, so even if it were 100% efficient needs at least 130 watts of "mains" power to do that. It will not be 100% efficient, so it actually need MORE than 130 watts of mains power.

 

Hence a 100 watt inverter is inadequate to run it, even if that inverter is continuously rated.

 

Personally in my example I'd not use an inverter rated anything less than 150 watts, and more would be better.

 

However, if you have a slim small screened laptop, it may use less, and the maths might suggest a 100 watt inverter is fine.

[Charlotte Burnett]

PSW if it contains critical data but really, I would want to know why it won't play with 12v, especially as it sounds like it did before. Can you explain a bit more what is going wrong?

 

A couple of friends lost dissertations and the consensus was Maplin MSW inverters caused this. Hopefully someone with a background in electronics will be able to explain a bit more in a moment. I use a small MSW in an emergency to charge the switched off cpu in the car. I figure this way, the worst that can happen is I cook the battery. This is not, however, based on anything more scientific than a hunch! As to the size, my Macbook Pro has a 60W PSU but I think my old 17" was 150W, have a look on the brick.

[GUMPY]

For a cheap PSW inverter I tried a 500w one from Ebay 320902251189

A good cheap unit.

In the end it wouldn't run my fridge but I knew I was pushing it.

Company took it back no question.

[eightpot]

Echoing one of the above posts, I'd be concerned that the laptop isn't slowly dying if it is getting more finnicky about its power supply. If it were me, I'd have that disquieting feeling that going from a 12v supply to an invertor/mains psu combo may only be a temporary fix.

[Starcoaster]

Charlotte, this thread: http://www.canalworld.net/forums/index.php?showtopic=59652&hl=laptop explains the issue I have/had. Since then we have replaced the socket (well, MB did, I held a spanner or something) and I don't really know what else he tested... He might remember though!

At the time I posted that thread, I was adamant that the laptop only had an issue on my boat, because when I use it on Mike's boats it's ok. EXCEPT that on Sunday I was using it on Reg, and after about half an hour the problem replicated.

I have tried loads of different 12vchargers of different types to check that that is not the issue.

 

Alan, on the back of the mains charger it says:

Input 100-240v 1.2A

50/60Hz

Output 19v dotty line 3.42A.

[alan_fincher]

PSW if it contains critical data but really, I would want to know why it won't play with 12v, especially as it sounds like it did before. Can you explain a bit more what is going wrong?

 

A couple of friends lost dissertations and the consensus was Maplin MSW inverters caused this.

 

I think the consensus is flawed!

 

All you are powering is a switched mode power supply, and the presence of that between inverter and laptop I believe makes it highly unlikely that the waveform of the inverter will cause the power supply to throw out anything horrible enough to do damage on the PC. Don't forget the power supply is itself connecting anyway to a bloody great laptop battery that I would have thought would further mitigate any problems from irregular waveforms.

 

I think the worst that might happen using an adequately rated MSW inverter is that it might refuse to run the "brick".

 

Happy to be corrected if I'm making some dumb assumptions though. (Gibbo would have known.... And Chris_W would then have challenged what he aid....)

Output 19v dotty line 3.42A.

 

So 65 watts then. A 100 watt inverter should have more than enough margin, so you can ignore all my words of caution!

 

It will probably be fine even if 100 watts actually means 100 watts PEAK / 80 watts continuous, but it is getting more marginal then.

 

If going as low as 100 watts, check it is a CONTINUOUS rating, (or buy a slightly bigger one!)

[Starcoaster]

Thank you.

[Justme]

 

Input 100-240V ~ 2.5A

Output 19.5V = 6.7A

 

The key point here is that 19.5 volts times 6.7 amps implies the power supply can deliver just over 130 watts, so even if it were 100% efficient needs at least 130 watts of "mains" power to do that. It will not be 100% efficient, so it actually need MORE than 130 watts of mains power.

 

 

 

Thats its output wattage. The bit you are interested in is the input wattage.

 

In your case the max amps are 2.5a which will only happen at the min voltage of 100v so a wattage of 250 watts peak.

[DeanS]

So 300Watt MSW it is then..LOL

[Geoff Taylor]

Hi, This may be a long shot but is it possible that your laptops battery is failing and the 12v supply is unable to charge it up and power the software as well. My laptop (dell d600) battery failed and the mains transformer could not run it with the battery in but worked with the battery totally removed!, I guess the battery fail was a dead short or something as a new battery worked perfect. Might be worth a try to remove your battery and see what happens.

[Charlotte Burnett]

Alan - I see you have applied the same logic that I do in my car, logically - and it's a fair point. Computers, however, are powered by magic and witchcraft and I therefore recommend that Starry sacrifices a £20 note to one of those shops that repairs phones, cameras and Kindles that can be found in the less salubrious areas of Londinium and, presumably, also in the shires, often sharing premises with a nail salon, convenience store and a Western Union counter. Generally I find the level of wizardry to be greater carried out by these folk than in more upmarket areas. For christsake haggle though!

 

Basically, I've a suspicion that there is something failing around the power socket and so far have no reason to believe that it might not cause the implosion of Starry's universe and perhaps also that which we all share. Magic and witchcraft I say, magic and witchcraft.

 

(Bombay Sapphire is to be held responsible for any erroneous or libellous information in this message.)

[Starcoaster]

Computers, however, are powered by magic and witchcraft and I therefore recommend that Starry sacrifices a £20 note to one of those shops that repairs phones, cameras and Kindles that can be found in the less salubrious areas of Londinium and, presumably, also in the shires, often sharing premises with a nail salon, convenience store and a Western Union counter.

 

 

You're from Peckham too?

[bizzard]

Do you ever condition the battery Star by running the laptop on its battery alone until the battery low warning alerts you and then plug it in and charge it right up again. Doing that regularly improves the battery's condition and longevity.

[Starcoaster]

Yes periodically, maybe once a month. The usage time I get from the laptop when it's on the battery only and not plugged in is the same as it ever was and hasn't worsened lately, if that helps?

[Arthur Brown]

My old Dell will not work off cheap car to laptop units but does work happily from a maplin car cig lighter to 230v 75w MSW inverter. They also do a 175w inverter for plugging into the cig lighter.

 

HOWEVER the cig lighter connector is probably where part of the fault lies. maybe a properly wired small inverter would be better.

Edited September 26, 2013 by Arthur Brown

[Delta9]

I have this cheapy 150w inverter http://www.dbrico.com/es-ES/calefaccion/energias-renovables/inversor-de-onda-modificada-dc-ac-redondo-150w-c-usb-xunzel/1822/1

 

it can easily run my laptop and tv at the same time. 150w is plenty for any laptop.

[MtB]

 

HOWEVER the cig lighter connector is probably where part of the fault lies. maybe a properly wired small inverter would be better.

 

Exactly. This is the whole point of my suggestion to use a 240v inverter supplying a normal household laptop charger/power supply. It's the only way I can think of to avoid use of the cigar lighter socket.

 

I don't fink Starry explained the exact nature of the problem with the cigar lighter connectors. The male cigar lighter ends <schnerk> on the 12v chargers overheat and melt after a random amount of time.

 

MtB