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| Cold_n_Wet Member Since: 15 Oct 2012 Location: Bergen Posts: 244  
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id get a pure sine wave inverter, Laptops are sensitive items, I charged my macbook on a non pure sure wave and it didnt sound too good.
G "Rafiki" 2007 110 STW - Rolling rebuild. |
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12th Apr 2014 2:52pm |
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| ARC99 Member Since: 19 Feb 2013 Location: North Yorkshire Posts: 1831  
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Sine Wave, don't know what it means but that's one thing to add to a list then. Don't make old people mad.
We don't like being old in the first place, so it doesn't take much to  us off.
Richard |
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12th Apr 2014 3:35pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20483
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Yep, pure sinewVe is the way to go, naturally costs more though....
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12th Apr 2014 4:38pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971 
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If you're buying an inverter a pure sinewave one is better.
However, for charging a laptop/tablet, you're being fed BS. Assuming your DC/DC charger has a sufficient power output there's no point in needlessly converting from 12V DC to 230V AC and back to a low voltage DC. It's much more efficient to use a DC/DC converter. Now, it is the case that if you're comparing a bad quality DC/DC charger to a good quality mains one then the mains one might work better. For instance my car phone charger only has a 500mA output and is slow to charge if my phone is working hard. Compare that to my (actually out of USB spec) mains charger that will do 800mA and you can see that the latter has the potential to be faster if the phone will take the full current (which will be down to the phone's internal circuitry). You can usually get at least 10A out of an accessory socket which is 120W at 12V nominal. That's plenty to charge any laptop that I know of. Power out can never be higher than power in - in an ideal world an inverter would just step up the voltage and power in would be the same as power out. In reality they're far from that, hence the big fans you get on the large ones. There's one on the CPC website that claims to be 85% efficient, so if you're putting 100W in, you're only getting 85W out plus the balance of 15W of heat. Your laptop charger will be around the same. I hope that helps a bit? Edit to add: <geeky> About the whole sinewave thing. An inverter works by "chopping" the 12V DC (that is Direct Current, i.e. in relation to 0V it's steady and always positive) to create the AC (Alternating Current, in relation to 0V it alternates between something like -330 and +330 50 times a second, but averages out to give an applied power equivalent, known as RMS, to 230V). So, you've got your DC, turned it on and off rapidly, stuck it through a transformer to get the correct voltage and you're done, right? Well maybe. What you've not got is a square wave output, fine for running a kettle but that's about it. |_|-|_| Next stage is to put a bit of smoothing in, or modify how you do your chopping, and you get the next cheapest to product which is the sawtooth /\/\/\/\ or |\|\|\| or similar. Better, but not perfect. Best is pure sine, which gives nice, smooth even wiggles ~ like you remember from your maths lessons at school but that's the most expensive and complicated to do. In reality your mains laptop charger will probably be fine on anything, inside you've just got a big switched mode power supply and they run on anything, including mains voltage DC. So what's a switched mode power supply? Well it's in some ways it's the complete opposite of an inverter, in some ways it's pretty much the same. It works by turning on and off the power supply through a series of inductors and capacitors to give a nice smooth, regulated low voltage DC output. Now the DC/DC converter I'd much prefer you used to charge your devices on the go takes some elements of both of these. I'm not going to go in to much detail but if you want to have a look yourself the terms to search for are "buck converter" for lowering the voltage like in a phone charger, and "boost converter" for raising the voltage like in a laptop charger. There is also the combined "buck boost converter" which means you can have a regulated, say, 12V supply whether you have an input of 10V or 20V. *Removes electronic engineer hat* </geeky> Last edited by Cupboard on 12th Apr 2014 5:27pm. Edited 3 times in total |
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12th Apr 2014 5:02pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5741 
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Charged my laptop for several years on a cheap invertor. Never had any problems, it's always going via power pack of some sort, so unlikely will damage computer it's self.
I would see what V your computer is running on, power pack might just be making 12v. Pure sine is not required for the majority of stuff and is exspensive. Andy |
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12th Apr 2014 5:05pm |
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| Cold_n_Wet Member Since: 15 Oct 2012 Location: Bergen Posts: 244
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AC Power is generated in a wave form, from plus to minus, the cheaper inverter produce a square wave rather than a round / smooth power curve. Modern electronics are more sensitive to the fluctuations in the voltages. Most suppliers recomend to use a sine wave type.
Have a look here http://en.wikipedia.org/wiki/Power_inverter Using an inverter to generate 240v then step it down again must take more power then a DC/DC type. G "Rafiki" 2007 110 STW - Rolling rebuild. |
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12th Apr 2014 5:23pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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It might well be, but please don't just make a lead to go from socket to laptop. The 12V in a vehicle is very nominal, under normal operation anything from 10 to 15V is plausible and there will be lots of horrible high voltage spikes on top of that. If I'm building something to work on a vehicle power supply then I'll be putting lots of overvoltage protection in and lots of smoothing in too. |
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12th Apr 2014 5:26pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8582
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First off check what voltage and current YOUR laptop requires.
(Remember the exploding Electronic cigarette become a flaming missile in a N Yorkshire pub because someone plugged it into the wrong charger!) Once you have got that bit of information you can decide what charger you want to go for. Depending on your lap top maker they may well make a car charger for your lap top and that would probably be the best solution. A good quality DC DC charger with the right voltage and current will do the trick. If going for an invertor a pure sine wave is best rated at say 250-500 watts. Cheap invertors will give a poor waveform output and yes they may or maynot charge a laptop. One I have tried is a bit hit and miss about charging things like laptops. Brendan |
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12th Apr 2014 6:35pm |
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| ARC99 Member Since: 19 Feb 2013 Location: North Yorkshire Posts: 1831
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Best is pure sine, which gives nice, smooth even wiggles ~ like you remember from your maths lessons at school but that's the most expensive and complicated to do.
Have you read my tag line. School was 50 years ago. I'll re read the replies several time and try and make sense of them later. Don't make old people mad. We don't like being old in the first place, so it doesn't take much to us off.
Richard |
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12th Apr 2014 8:41pm |
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| Birdy Member Since: 07 Oct 2011 Location: Côte d'Azur Posts: 869  
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Something like this?
http://www.amperorassociates.co.uk/c-DC_po...r_S1U.html Peter |
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12th Apr 2014 8:49pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8582
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ARC99 read the base of your laptop/charging instructions carefully
I thought laptops were 19V however have just turned mind over and it is 16.5 volt 3.65 amps So before opening your wallet check what your laptop/equipment requires then start your decision making process based on factual information about your actual requirements Guessing it is 5 volts or 19 volts is not good enough you need the factual information about charging your equipment before you make any decision. Brendan |
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12th Apr 2014 9:22pm |
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| bpman Member Since: 21 May 2008 Location: Oslo Posts: 8069 
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I have a Kensington car kit that works fine with my toughbook, expensive but you get what you pay for
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12th Apr 2014 9:27pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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No, in a word! That gives you a regulated 12V which is only useful if the thing you're trying to supply wants 12V, which it probably won't. Laptops IME range between 9V for small ones to 18V for larger ones. You can get some universal chargers, but they only work with certain ranges of laptops. Funny definition of universal IMO. You can get 3rd party and OEM car chargers, and some that are variable voltage with changeable tips. What sort of laptop are you trying to charge? |
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12th Apr 2014 10:13pm |
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| Pam W Member Since: 25 Oct 2011 Location: North Yorkshire Posts: 1169  
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For our Apple laptop we are using a 12volt charger via the cigar lighter socket. It takes quite a lot of current so we usually charge it on the go - with the cigar lighter socket being powered from our auxiliary battery and therefore causing minimal impact on our overall capacity.
The 12v adapter is more efficient than using an inverter. The charger we got cheap off eBay or amazon and works fine, a lot cheaper than the cost of an inverter and smaller to store. Not having an inverter also means we are not tempted to carry or use additional electric appliances that would just end up draining the aux battery quicker and taking up space..... No hair dryer for me then!  Our blog - http://landytravels.com/
Yorkshire Off Road Club - http://www.yorkshireoffroadclub.net |
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13th Apr 2014 2:19pm |
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