12v to 19v - DC to DC (any recommends?) or small inverter?

demonboy

demonboy

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I've never had a problem with mini inverters (80w-150w) to power my hard drives and laptops (the whole pure sine wave argument is a nonsense from my experience), but now I need to power an LED TV. On the back of the TV it has a rating of around 2.5amps at 19v. I'm interested to know which is more efficient: a small inverter (drawing around 0.4amps on standby) or one of those laptop 12v to 19v DC-DC cigarette adaptors?

I use both types on the boat but now that I'm back in the UK I'm really struggling to find a decent DC-DC laptop adapter that comes with a good rep. This is the sort of thing I'm after: http://www.amazon.co.uk/Universal-C...id=1406834045&sr=1-14&keywords=12v+car+laptop but as you can see the reviews are mixed.

Since the TV won't be on that much (just a couple of hours to watch a film) I'm wondering if it would just make more sense to install a small Bestek inverter instead.

Any thoughts?
 
demonboy said:
I've never had a problem with mini inverters (80w-150w) to power my hard drives and laptops (the whole pure sine wave argument is a nonsense from my experience), but now I need to power an LED TV. On the back of the TV it has a rating of around 2.5amps at 19v. I'm interested to know which is more efficient: a small inverter (drawing around 0.4amps on standby) or one of those laptop 12v to 19v DC-DC cigarette adaptors?
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It should be less efficient to create 240V and then step it down. You'll have heat from the invertor and heat from the power supply. I'd put a 19V step up on.

I use both types on the boat but now that I'm back in the UK I'm really struggling to find a decent DC-DC laptop adapter that comes with a good rep. This is the sort of thing I'm after: http://www.amazon.co.uk/Universal-C...id=1406834045&sr=1-14&keywords=12v+car+laptop but as you can see the reviews are mixed.

Since the TV won't be on that much (just a couple of hours to watch a film) I'm wondering if it would just make more sense to install a small Bestek inverter instead.

Any thoughts?
Click to expand...
The invertor has the advantage you can plug other things in. (When someone comes with a really old mobile with a non-standard charger?) So might win...

No experience of those specific bits of kit. BUT if you read the moans they are basically 3 fold. Didn't work - wonder how many are sold - negative feedback always happens cause someone bought the 1:10,000 that failed. Does't have enough power. You should be OK, it'll be people with large screen laptops with WiFi plus hard drive plus DVD drive all trying to power up at once that is an issue. The connectors don't fit. I cant say if thats an issue for you - it may be. But you can chop the end off and attach one of your choice bought for a few pence...

Personally I'd give one of these a punt:

http://www.ebay.co.uk/itm/DC-DC-Con..._Measurement_Equipment_ET&hash=item3a80f54f77
 
Actually, technically, an AC to DC switch mode device is no more or less efficient than a DC to DC device. The efficiency comes from low 'on' resistance of the switches and the speed with which they switch. The difficulty is in finding a decent adapter!

The real test is to turn them on and see how warm they get. Which is also, in my experience, an excellent guide as to how long they last.

I bought a Maplin DC to DC device for a laptop. Not only does it get warm it also leaves enough switching noise to break through the audio on the laptop. It's in the garage somewhere....

If you get an inverter check the minimum input voltage. Mine flips out at 12 volts which is too high with my dodgy wiring.
 
ShinyShoe said:
Personally I'd give one of these a punt:

http://www.ebay.co.uk/itm/DC-DC-Con..._Measurement_Equipment_ET&hash=item3a80f54f77
Click to expand...

I bought one of these for my printer a few days ago, will report back when it arrives.

For my monitor I use one of these: http://amzn.to/1k56jzr as it has a 230V input as well as 12V, thus removing a load from the battery while charging. See this thread: http://www.ybw.com/forums/showthrea...wering-Notebooks-TVs-and-other-gt-12V-devices
 
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demonboy said:
I've never had a problem with mini inverters (80w-150w) to power my hard drives and laptops (the whole pure sine wave argument is a nonsense from my experience), but now I need to power an LED TV. On the back of the TV it has a rating of around 2.5amps at 19v. I'm interested to know which is more efficient: a small inverter (drawing around 0.4amps on standby) or one of those laptop 12v to 19v DC-DC cigarette adaptors?

I use both types on the boat but now that I'm back in the UK I'm really struggling to find a decent DC-DC laptop adapter that comes with a good rep. This is the sort of thing I'm after: http://www.amazon.co.uk/Universal-C...id=1406834045&sr=1-14&keywords=12v+car+laptop but as you can see the reviews are mixed.

Since the TV won't be on that much (just a couple of hours to watch a film) I'm wondering if it would just make more sense to install a small Bestek inverter instead.

Any thoughts?
Click to expand...

I use a similar item from maplins, it also has 2 usb ports as well
 
dylanwinter said:
I have had good success using an American inverter - stepping up to 110volts and then powering stuff from there

smaller and runs cooler than 240 volt inverters

https://www.youtube.com/watch?v=Q__IqhvZgS8
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We need to be a little careful of Dylan's logic. An inverter supplying 110VAC into a charger or power supply will have to supply twice as much current as an inverter providing 240vac. Mind you in providing 110Vac in ragged square wave there is less chance of damaging the charger or power supply.
I suspect that if Dylan found his 110vac inverter gets less hot then that is because it is a more efficent inverter. Likewise if he found the 110v inverter draws less current then that is because it is more efficent. good luck olewill
 
nigelmercier said:
The one in my Post #5 does, but of course won't work with a Dell without modification.
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Pete7 said:
But the Maplin one will, £19.99, bought one last week to bail me out of a fix when the the original Dell charger failed.
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To clarify: Dell chargers require a special chip inside them to tell the laptop their capability, they have three wires rather than two. A generic charger will power the laptop, but it will not charge properly and it may run at reduced speed. The plug has three contacts, the outside of the barrel, the inside of the barrel, and a very thin pin which is the data line. If you look in the BIOS (called Settings as you boot) it reports the type of charger.
 
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demonboy said:
I've never had a problem with mini inverters (80w-150w) to power my hard drives and laptops (the whole pure sine wave argument is a nonsense from my experience), but now I need to power an LED TV. On the back of the TV it has a rating of around 2.5amps at 19v. I'm interested to know which is more efficient: a small inverter (drawing around 0.4amps on standby) or one of those laptop 12v to 19v DC-DC cigarette adaptors?

I use both types on the boat but now that I'm back in the UK I'm really struggling to find a decent DC-DC laptop adapter that comes with a good rep. This is the sort of thing I'm after: http://www.amazon.co.uk/Universal-C...id=1406834045&sr=1-14&keywords=12v+car+laptop but as you can see the reviews are mixed.

Since the TV won't be on that much (just a couple of hours to watch a film) I'm wondering if it would just make more sense to install a small Bestek inverter instead.

Any thoughts?
Click to expand...
Maplin offer several. I have two from them that look very like the one in your Amazon link. (They don't make my exact model any more.) I have used them without problem for about 10 years. This has spanned five laptops from three different manufacturers, including a Dell, which worked without any problem. I have a Sterling 240 volt inverter. I have explicitly done the test many times to see how many amps it takes out of the battery via the DC-DC vs the inverter and AC charger. In my hands the inverter solution seems to take about twice as much current, though can't see why it should.

With my present Lenovo laptop I discovered that Lenovo supply a 12 charger at a reasonable price, and it is far less bulky - I use it.

I'm willing to bet that your laptop manufacturer will have a recommended solution if you probe.
 
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