12v dc to laptop without inverter

Sep 29, 2016
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Anyone have suggestions for the subject topic ?

Just to power a typical laptop from caravan 12v accessory socket, I don't suggest you watch all of the video below, I just posted it for illustration.

From what I can gather this type of device draws around 5 amps to power a laptop, seems a lot to me, perhaps there are more efficient devices methods.

https://www.youtube.com/watch?v=WV5XSE736wM
 
Mar 14, 2005
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Anseo said:
Anyone have suggestions for the subject topic ?

Just to power a typical laptop from caravan 12v accessory socket, I don't suggest you watch all of the video below, I just posted it for illustration.

From what I can gather this type of device draws around 5 amps to power a laptop, seems a lot to me, perhaps there are more efficient devices methods.

Sorry but your title is misleading. The device you are pointing to is an inverter, though it may not be titled as such.

Inverters (DC) and transformers(AC) are examples of theoretical constant power devices. This means the device will have the same power (Watts) flowing through its input as flows through its output. What changes is the volts and amps which are inversely related, if teh volts goes up teh current capacity reduced proportionally and vice versa.

You tell us the Maplin device you point to is rated at 12V @ 5A = 60W . In theory if it were 100% efficient you should get 19V@ 3.1A =60W But such devices are not 100% perfect so it will probably be closer to 19V @ 2.6A = 50W, and the device will use about 10W of power to run.
 
Oct 8, 2006
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Unless there is a very specific need to use a laptop, the easy answer is to use a tablet. Not cheap I know but they run and charge off 5V so inverters are not needed.

If a laptop is mandatory then be sure to get a pure sine wave inverter as distinct from one of the 'modified sine wave' variety as the latter could easily damage the laptop PSU that you are going to connect into it. Pure sine wave inverters are usually getting on for twice the price of a a modifed sine wave type. This device is a good example of what you need inverter but not cheap.

Incidently a 300W inverter does not take 300W when running: it will only take the power drawn by the device connected to it plus an efficiency coefficient. Most inverters are better than 80% efficient so if you are drawing say 60W the power drawn from the supply will be 60 x (100/80) or about 75W or less. 75W at a nominal 12V is 6.25A - make sure your 12V outlet can handle that as some are fused at 5A.
 
Jun 26, 2017
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ProfJohnL said:
Anseo said:
Anyone have suggestions for the subject topic ?

Just to power a typical laptop from caravan 12v accessory socket, I don't suggest you watch all of the video below, I just posted it for illustration.

From what I can gather this type of device draws around 5 amps to power a laptop, seems a lot to me, perhaps there are more efficient devices methods.

Sorry but your title is misleading. The device you are pointing to is an inverter, though it may not be titled as such.

Inverters (DC) and transformers(AC) are examples of theoretical constant power devices. This means the device will have the same power (Watts) flowing through its input as flows through its output. What changes is the volts and amps which are inversely related, if teh volts goes up teh current capacity reduced proportionally and vice versa.

You tell us the Maplin device you point to is rated at 12V @ 5A = 60W . In theory if it were 100% efficient you should get 19V@ 3.1A =60W But such devices are not 100% perfect so it will probably be closer to 19V @ 2.6A = 50W, and the device will use about 10W of power to run.

The device isn’t an inverter Prof, it’s a step-up DC converter, and I would suggest it’s the best and most efficient method for Anseo to power/charge his Laptop in the caravan.

He would only need an inverter if he wanted to go from 12VDC to 240AC and then use his regular switched mode PSU to produce the 19VDC or whatever voltage his laptop requires, and of course, there would be no sense in that, not least because of the resultant double hit with the power losses and the birds nest of cables and little black boxes !
 
Mar 14, 2005
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Hello Icau5

The way the majority of step up dc to dc devices work is to take the input dc and feeds it via a 'solid state ' switch to chop it. This is fed through an inductor which builds a magnetic field around it. When the DC is cut off, the magnetic field collapses and will ring oscillate producing a bust of ac current this is rectified and the peak pulses are stored on a intermediate capacitor from which the charge at a greater voltage than the input voltage.

This fits the description of an inverter which is a device that converts dc to ac, its just that the unit then has to further rectify teh AC and regulate it.
 
Oct 8, 2006
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I can find no record of anything like this shown on the Maplin web pages.

Could this product be from the 'old' Maplin no longer in business?
 
Mar 14, 2005
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Woodentop said:
I can find no record of anything like this shown on the Maplin web pages.

Could this product be from the 'old' Maplin no longer in business?

Yes!

I was not aware that a new company called Maplin online had started until your post.. Having looked at their web site, whilst the branding utilises the last company logo, it does not cater for the electronic hobbyists anymore.
 
Jun 26, 2017
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ProfJohnL said:
Woodentop said:
I can find no record of anything like this shown on the Maplin web pages.

Could this product be from the 'old' Maplin no longer in business?

Yes!

I was not aware that a new company called Maplin online had started until your post.. Having looked at their web site, whilst the branding utilises the last company logo, it does not cater for the electronic hobbyists anymore.

Unfortunately Prof, due to dwindling interest in electronics as a hobby, the original Maplins had already started going in that direction ... what first appeared as a single row of overpriced, fully assembled Chinese tat slowly started to run deeper into the stores, swallowing up the isles of reasonably priced components aimed at the enthusiast until their stores became little other than overpriced, unbranded toy stores. Hence their demise.

It was then that Peter Jones of Dragons Den fame bought the name, branding and intellectual rights which he now uses to peddle some of his wares.
 
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I too am unable to find any concrete confirmation, but I seem to remember it being in the media at the time. Perhaps I am completely wrong, or he bought the name and sold it ?

Interestingly enough, their website states their company name as “Maplin Online Limited” but a quick search on Duedil reveals that the company changed its name just 9 days ago to “Digital-First Retail Limited”, and has just one 27 year old director, with no obvious link to the aforementioned gentleman. I would expect that they will keep using the Maplin name though.
 
Mar 14, 2005
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I wouldn't agree that electronics is a dwindling hobby, it has certainly changed, Surface Mount rather than Through Hole, large-scale integrated circuits, and the move towards software implementation rather than hardware solutions but there are still a few die hard vacuum tube fans out there.

We have seen a lot of changes in the way people access their hobby information, the internet has probably superceded the hobbiests magazines as the most common source for information, as we have seen with caravanning.

More specifically related to Maplin, it's my take on the matter that when Maplin started in 1972, it was hobbiests running it, and it focused on supplying components. When the founders sold it, it was taken on by a commercial business, and they were more motivated by profit and expansion. The closure of Tandy in the UK left a hole in the market which successive owners of Maplin tried to fill, and for me that was where Maplin lost the plot. They should have closely looked at what caused Tandy to fold, because they followed almost the same model with the same consequences. Expanding beyond the niche they filled by taking on a wide range of ready made products which were generally not as good as the market leaders, barely undercutting them, and putting their original core business into jeopardy by ramping up prices to pay for shop space, and reducing the range until it made it difficult to get everything you need for a project from them.
 

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