Guest barrie Posted January 4, 2006 Share Posted January 4, 2006 i know you pays your money & takes your choice but i've just found a 150w inverter in aldi for £15. if it runs the laptop for that cost i'll be happy ! Link to comment Share on other sites More sharing options...
Guest Mel E Posted January 4, 2006 Share Posted January 4, 2006 I'm sure it's fine for most things: recharging shavers, etc. But personally I would not run delicate electronic equipment off it unless they have their own built-in power stabiliser. Computers are notoriously sensitive to voltage changes. Why risk a £750+ laptop for the sake of saving a few ££s. A good 150w inverter is available from Maplins and others for around £50 or so and a full sine wave output model for not a lot more. Link to comment Share on other sites More sharing options...
Guest bill h Posted January 4, 2006 Share Posted January 4, 2006 Assuming I buy an inverter as described from (Maplin). Is there a rapid demand on the Leisure battery(s) or will they stand some hours use by the laptop? bill h. Link to comment Share on other sites More sharing options...
Guest Don Madge Posted January 4, 2006 Share Posted January 4, 2006 Hi Bill, I have a 150 watt inverter from Maplins and I have two 100amp leisure batteries, it runs my laptop with no problems. I often use the laptop for three or four hours in the evening. We also charge the camera batteries, mobile phone and my razor. Clive MG is the man you want for info on inverters. Regards Don Link to comment Share on other sites More sharing options...
Guest Clive Posted January 4, 2006 Share Posted January 4, 2006 Here's something I prepared earlier. :- There are two main kinds of inverter and they have significant differences: Square wave inverters are the least expensive type. They are usually very efficient, light, and compact and are available in models supplying less than 150 watts to others which can power equipment requiring several Kilowatts. They work by roughly replicating the voltage waveform produced by the 240V mains electricity supply but the waveform they produce is far from smooth and is composed of square waves with gaps. The result is that some appliances won’t run as smoothly, as efficiently or as quietly as they would normally. Microwave ovens may take a lot longer to cook; power tools may be a bit gutless and some equipment may not like it at all!. For many applications however, a modified sine-wave unit will do the job. Examples of devices that work happily include devices like flat screen televisions and laptop computers which use in line mains power adapters that are designed to work over a wide range of operating voltages and frequencies, typically 100 volts up to 250 volts so as to be suitable for both the UK 230 volt 50 Hz market and the American 110 volts 60 Hz market. These power adapters achieve this by first rectifying the AC into a high voltage DC then using this DC to supply a small efficient high frequency inverter to power a ferrite cored transformer which is followed by another rectifier and smothing circuits. Electronic feedback of the output voltage within these small power adapters modifies the switching of the initial inverter within the module to regulate the output voltage accurately. The small power adapters for flat screen TV's, Laptops etc do provide galvanic electrical isolation for the end equipment over a wide operating input voltage. Pure or True sine-wave inverters produce A.C. electricity in a smooth sine wave which is virtually indistinguishable from that supplied by the National Grid. As a result, any mains electrical appliance will run just as well on this type of inverter as it will when plugged into the mains. Their one disadvantage is that they are considerably more expensive but, if the inverter is to be used frequently for equipment that requires a pure sine wave or if maximum performance is essential, they may be worth the additional cost. Modified sine wave mains inverters are not so good for mains equipment where mains frequency transformers are used or for powering mains AC motors. Whichever inverter you choose, it’s essential to get one that is capable of providing the power which the appliance requires to both run and start, plus a bit in hand!. Its very important that you appreciate the limitations of an inverter. For instance, one is unlikely to run a normal domestic kettle from an AC supply derived from an inverter in a motorhome. Say the electric kettle is a normal Domestic 2.4 killowatts model. On the 240 volt mains supply this will take 10 amperes, but the input current to the converter (presuming it were big enough and were 100% efficient) would be 200 amperes. As the converter is likely to be nearer 90% efficient then the battery current would be 220 Amps. So, Inverters are normally used in motorhomes to power mains type equipment that is not normally used for heating. Like TV, Video, Computer, Satelite etc. Occasionally a small microwave oven, but these will still cause the inverter to draw something between 50 and 100 amperes from the battery. You need to have a BIG battery if you intend to do this on a regular basis! Lastly, even when an inverter is not powering any equipment it will still draw a small but significant "quiescent current" when switched ON, so when not in use a inverter must be switched OFF. Hope that helps C. Link to comment Share on other sites More sharing options...
Guest bill h Posted January 5, 2006 Share Posted January 5, 2006 I see a 12v Maplin Inverter is 39.99. I assume that does not include assesories like cable and connectors. Also the shorter lead is better regarding loss of energy in cable length. I assume also a cigar lighter connector is more convenient than battery clips. Is that 39.99 item up to the job, it doesn't seem pricey for the convenience. bill h Link to comment Share on other sites More sharing options...
Guest Dave Newell Posted January 5, 2006 Share Posted January 5, 2006 In Essence I agree with Clive. The only point I would make is that units are available which directly convert your (nominal)12 volt battery supply to a suitable voltage for your laptop (i.e. 15, 16.....20volts). If you want to power a laptop my preferrence would be for one of these units from a reputable supplier as it's more efficient to simply "up" the DC voltage than convert it to 240vac then back to 15 (or whatever) vdc. The Aldi unit is every bit as good as the Maplins units, my father just bought one and it does exactly what it says on the tin. If possible use the croc clip leads directly onto your battery as the ciggy lighter is 1. wired from your engine battery and 2. the wire in between the socket and the battery adds voltage drop which will cause the inverter to cut out early. A couple of advantages to buying from Aldi is their returns policy and guarantee period, if you aren't satisfied with your purchase for any reason take it back within 30 days for a no quibble refund, and yes they do not quibble. Also many items they sell carry a 3 year guarantee (check because this doesn't apply to everything). Regards and happy new Year to all, dave@davenewell.co.uk Link to comment Share on other sites More sharing options...
Guest Brian Kirby Posted January 5, 2006 Share Posted January 5, 2006 May I just add to that? The laptop specific car type converters are quite expensive, though. They are also a bit limited, in that unless you replace your laptop with a very similar one, you are likely to need a new converter for each laptop. Since laptops don't last as long as motorhomes (please!) last, I think a one off inverter installation in a motorhome will be cheaper, in the long run, than several different car type converters. Further, although there are cheap, generic, car converters, laptop charging voltages are very varied, and you can't always get one suited to your particular machine from a source other than the laptop manufacturer. Also, if you fry your laptop using a converter from an alternative source, you will probaly have invalidated your laptop warranty. Last point: an inverter can be used to power more things than just the laptop, for example printer, camera, razor etc. The car converter probably won't do more than just the laptop. Regards Brian Link to comment Share on other sites More sharing options...
Guest Dave Newell Posted January 5, 2006 Share Posted January 5, 2006 Brian, I bought a laptop dc-dc converter from Action Replay for £20. It is not machine specific and will give a selectable output voltage from 15 to 20 volts and comes complete with a range of connectors to suit pretty much any laptop on the market. I have checked its output with an oscilloscope and the output voltage is rock solid and perfectly smooth (as good as the Toshiba PSU that came with the laptop) even if you start the engine while the laptop is connected and running through the dc-dc converter. I consider £20 to power a £500+ laptop as reasonable cost and it's more efficient than running an inverter to power the laptop via its original 240vac-15vdc power supply. dave@davenewell.co.uk Link to comment Share on other sites More sharing options...
Guest Brian Kirby Posted January 5, 2006 Share Posted January 5, 2006 Dave Thanks. I don't have an ocilloscope so can't check the outputs. However, my laptop (Fujitsu) takes 16V. Does the Action Repay item do 1 volt increments? Brian Link to comment Share on other sites More sharing options...
Guest Clive Posted January 5, 2006 Share Posted January 5, 2006 Brian, Dave and I have have this debate on and off periodically and there are good arguements in both directions. Personally I prefer to trust the isolation provided by the Laptops own power converter and have the bonus of an inverter I can use for other devices. Laptops do not take a lot of power and the differences in overall power consumption between the two methods is not significant. I also purchased a £39 inverter from Maplins some time back and it does the job OK. You pays your money and you makes your choice! Good luck Clive Link to comment Share on other sites More sharing options...
Guest barrie Posted January 5, 2006 Share Posted January 5, 2006 isn't it wonderful that the subject matter from a tight old sod like me can provoke such interesting debate? i now feel justified in spending such a vast sum. thanks to you all. (will be in touch clive) Link to comment Share on other sites More sharing options...
Guest Dave Newell Posted January 6, 2006 Share Posted January 6, 2006 Brian, Yes the Action Replay unit does 16 volts. Prior to buying that unit I did use an inverter to run the laptop for DVD viewing but found it caused interference on the sound when played through the CD/radio unit in the van, the dc-dc unit cured this particular problem. Don't get me wrong Clive, I do own a couple of small, cheap inverters but prefer to run the laptop via the dc-dc unit. I have used the inverter for work to power a 240v lamp and a soldering gun when mobile fitting work was more of a mainstream occupation for me, I now use a 12 volt lamp and a gas powered soldering iron for mobile work. I use the 150 watt inverter in the motorhome for emergency use i.e. one of our phones or a camcorder battery needs charging for example but wherever possible I prefer to use 12 volt equipment if its available at sensible cost. In answer to the original post, £15 for a 150 watt inverter is worth paying as they can be useful but in my opinion (humble of course) only for emergency/occasional use. Link to comment Share on other sites More sharing options...
Guest Brian Kirby Posted January 6, 2006 Share Posted January 6, 2006 To both Clive and Dave, thank you for your replies and the info. Regards Brian Link to comment Share on other sites More sharing options...
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