Inverter or 12v Laptop adaptor -

[SamsBus2012]

Whilst away camping over the weekend, we enjoyed the benefit of hookup so had the benefit of using the laptop to play a dvd for the kids on sunday evening whilst it was persisting down outside keeping them temporarily confined to quarters. I would like to maintin this benefit when not on hookup. So in short, any recommendations on using a low wattage inverter or one those cheapy 12v laptop adapters. My laptop has a 20v 65w supply (so just over 3 amp draw - will this increase through losses in any inverter/adapter? I use a 90Ah battery.

[ghost123uk]

Inverters are very efficient these days. Cheap 12V to 19V Laptop adapters are notoriously dodgy (being mostly cheap Chinese carp). I use a 300 Watt inverter for my Dell laptop with no issues. Plus, you can use the laptop for other things (but taking into account it's power capability in Watts of course). Inverter for me every time (30+ years as an electronics engineer).

I also use a DVB-T USB Freeview adapter with a magnetic roof aerial to pick up Freeview TV. These days the coverage has increased hugely and as long as you are not right out in the sticks, you get a signal.

[ghost123uk]

My laptop has a 20v 65w supply (so just over 3 amp draw - will this increase through losses in any inverter/adapter?

Oh, just to add, that 65W (3A) draw is "worst case scenario", like burning a DVD whilst listening to music and charging the battery.

My Dell Vostro says 90W but on normal use say, watching Freeview it only uses about 1.5 amps. Using an inverter to power it (them) will likely only increase consumption by ~10%, and remember, those 12V to 19V adapters are not 100% efficient either.

[SamsBus2012]

Cheers for that, hadn't though of a usb dvb that's a good tip . Got any recommendations for an inverter? Overwhelming choice on fleabay all around £25 - £40 sound about right?. Maplins seem to nudge the price up a bit.

[ghost123uk]

Difficult to choose. I am guessing most of them are made in China these days Mind you, iPhones are made in China and some folk like them

I don't even know what make my (300W) one is and I only bought it (off Ebay iirc) because of the price and the fact it was a UK seller at least. It has been OK for 18 Months and it gets used every day (see "Aside" below).

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Aside = I don't use a normal split charging system. I do have a normal split charge relay, but it's output feeds the inverter, so the inverter fires up every time the engine does. I then have a 12A "intelligent" charger attached to the inverter, feeding the leisure battery. This way, the intelligent charger is doing it's intelligent charging all the time the engine is running and my two batteries are never actually connected together. This is a good thing It's like a poor man's Sterling charger system.

I also have a "changeover" switch so I can run the inverter off the leisure battery when parked up, for the laptop (and occasionally a guitar amp type system, for guitars, or when I want my music loud outside the van ).

By the way, it's amazing how much audio amplifier power a 300W inverter can supply This is because a "P.A." or Guitar amp, rated at say 500W never actually uses anywhere near 500W (rms). It would only do that if was being asked to produce "white noise" at full volume and not "ordinary" music who's average power is well below that figure. High currents demanded by bass notes are catered for by substantial capacitors in such amps (cheaper than big transformers), but this is getting a bit techy now.....

[CJH]

You might want to consider whether you need a 'pure sine wave' inverter for you application. These tend to be more expensive than the 'modified sine wave' type, because they produce a waveform that's closer to what you'll get from a socket in your house. According to this document, some devices don't work so well from modified sine wave inverters - they include a handy 'compatibility chart' at the end of that document, and interestingly they list laptops in the 'maybe' column. I bought one of these.

I can't really comment on how well it works, as I've hardly used it, but it seemed to work well with my daughter's laptop last summer.

[colinthefox]

My vote goes for the DC/DC converter. I use one which cost me only a few quid and it's fine. All this kind off stuff is made in China now. How do you tell what's carp and not carp till it goes pop.
My converter hasn't gone pop..................yet.

I put it in the bag with my laptop, so I can use it in any vehicle. I have taped over the voltage selector switch though, to prevent it changing accidently!

[ghost123uk]

That pure sine wave inverter CJH linked to is good value for money in the world of pure sine wave ones (providing it is of good build quality) but in my (long) experience there is very little, if anything, that "we" are likely too use in a campervan that needs pure sine wave. I have used at least 4 different laptops, with 2 different non sine wave inverters in recent years, and they have all been fine.

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Aside = I love the wording of the text in that Ebay listing =

This power inverter instantly convert low voltage DC power to high voltage AC household power. High reliability and low failure rate by using the advanced Double-CPU single chip intellectual control technology. Small light and artistic, benefited from adopting the SMD pastern technology. Cooling fan is intellectual controlled, and working status is controlled by CPU, which mostly increased its service life and helps to save the power consumption, improve work efficiency and lower the working noise

Not as bad as some I have seen, but far from good

[Miss Syd]

would an invertor such as this power a 1500-2000w hairdryer safely? If not, could anyone recommend one that could?

[LeeME3]

would an invertor such as this power a 1500-2000w hairdryer safely? If not, could anyone recommend one that could?

To run such a device SAFELY you need a pretty serious inverter, this sort of thing: http://www.amazon.co.uk/BESTEK-inverter ... B00CI0PB0E" onclick="window.open(this.href);return false;

And, unless you've got a serious number of leisure batteries you're gonna run your power down very quickly and of course increase the number of dis-charge/charge cycles which in turn will kill battery life!

As an example...a common leisure battery is 88Ah. 2000w at 12V will pull 167Ah. You really don't want to take your battery below 60% to preserve its life so you have about 35Ah available. Therefore, assuming a brand new battery and a 100% efficient inverter (i.e. this is still 'perfect world') you'd get 35/167*60 = 12.5 minutes of hairdryer use! Also assumes no other loads on said battery at all. In reality I personally think it's not really practical.

However, at much lower cost and with 100% efficiency I can recommend: http://www.amazon.co.uk/Linens-Limited- ... ords=towel" onclick="window.open(this.href);return false; which will draw precisely no power at all from your batteries!

(Sorry couldn't resist)

[CJH]

would an invertor such as this power a 1500-2000w hairdryer safely? If not, could anyone recommend one that could?

2000w at 12V will pull 167A....

....which would require some mighty cables between the inverter and the battery - something like jump leads.

[CovKid]

Agree with ghost on 12v to 19v style adapter. You'll be lucky if it lasts a year. Very badly made. Mine caught fire eventually. Better to get a notebook or tablet that already runs on 12v. Add a smoother if paranoid.

My new laptop is powered via a USB cable.

[Miss Syd]

thanks for the hairdryer reply guys, I guessed as much. I will have to make do with a 12v one but by all accounts they are pretty pathetic!

[LeeME3]

thanks for the hairdryer reply guys, I guessed as much. I will have to make do with a 12v one but by all accounts they are pretty pathetic!

Or shave your head for charity.

[discipleofsketch]

I tried a DC to DC converter for my laptop, I didn't trust it, used to get very hot, which I guess also means it can't have been very efficient. It also used to make a strange whistling sound when the 12 volt source dropped below a certain level, so I just didn't trust it. Much better results with an inverter, even though in theory it is less efficient.