Can you power/charge a laptop via 12 volt socket?

[Bulletguy]

sshortcircuit - 2013-07-18 4:48 PM

 

I have a Dell laptop and a cigarette type charger from Maplin that provides various voltage to charge laptops. I cut off the plug from an old Dell PSU and soldered it to this unit and hey presto, it did not work. After further investigation I found that the Dell PSU has three connection, being positive, negative and a signal core which identifies the PSU to the laptop. A look on ebay indicated specific adapters are available for the Dell.

 

 

Thats correct.

 

My laptop is a Dell and they did a very clever little piece of marketing in making any other non-original charger/plug virtually u/s and forcing Dell owners to buy the Dell chargers.

 

Non-original will run........but won't charge the battery! Very clever!

 

I bought an original pack set for 12volt use off ebay and paid quite a bit more than what are currently on now. Must admit though, the pack is very comprehensive and typical Dell quality.

 

 

[Guest 1footinthegrave]

sshortcircuit - 2013-07-19 12:39 PM

 

Mrs T - 2013-07-19 12:01 PM

 

1foot and others, what's all the fuss, we've used the one described earlier for years. It charges the laptop battery with no difficulty but as soon as its full we disconnect the plug, it used to be said that the engine should be running when plugging in and that can be done easily. Its always wise to check for heating of any 12v plug as they can often be a bit loose and may not be pushed home tight enough to make a good connection.

Info from Mr T

 

No real fuss, you just need to understand that some chargers are specific to the laptop and it appears you have been lucky having a laptop that does not need an intelligent charger so the mult-volt has worked. Good luck to you, but some may want to purchase a multi-volt and find it does not work so have wasted money. Cant make it any clearer. :-D

 

Just to add, for those that have used one of these devices with success, how about a name and a supplier to help the guy out. Considering the multitude of DC sockets on laptops though I'd be very careful that the one you get is going to be up to the job, a laptop is an expensive piece of kit to ruin as we know. This is just one review of many that would make me very cautious indeed though.But as they say, it's your funeral. ;-)

 

Iv been using this charger with my Acer Aspire laptop for a few months now and its working fine. It often gets very hot but so dose the mains charger so I don't think this is a problem. At less that half the price of the next cheapest one I think its very good value for money.

 

Update

I take it back, charger expired in a big cloud of smoke while i was driving, its totally dead now.

 

Edit by me, I've just re-read the OP says he has a 300 watt inverter, why are you not simply using that to plug the laptops power supply into, that's what I do, and so far ( touch wood ) it works fine, no need for adapters at all.

[ips]

http://smartparts.co.uk/catalog/car_dc_adapters/

[BGD]

ips - 2013-07-19 2:30 PM

 

http://smartparts.co.uk/catalog/car_dc_adapters/

 

 

 

An excellent link, thank you!

[Guest 1footinthegrave]

Perhaps you missed my post, you have an inverter, just plug your laptop, the bit with the plug on and the black brick thingy on it that has the small plug on the end to go into your laptop, and just use it as if you were on the mains, that's what an inverter does, changes 12 volts to 240 volts, you don't need to buy a thing. :-S

[lennyhb]

Yes but not as efficient as using a dc to dc converter and you have another fan running disturbing the peace.

As Bruce like you Mike & me tend to camp off grid the less power taken from the batteries the better.

[Guest 1footinthegrave]

Point taken, however if you read the blokes original post he seems to know as much about it as I know about brain surgery,I was just trying to save him some grief by just using his inverter as he does not seem to understand he has the ability to use his laptop without further expense, as for fan noise I've got a 1200 watt one, more than enough poke for a laptop, and I've yet to hear any fan noise at all, although I mainly use it purely as a charger for all things rechargeable. ;-) just hope the bloke doesn't blow himself or his laptop up whatever he decides.

[sshortcircuit]

"and you have another fan running disturbing" Well my inverter does not have a fan so it has to be more efficient. It would be really interesting if somebody had the actual facts and figures to compare an inverter to a dc to dc converter as whatever you do you get nout for nout.

[Guest 1footinthegrave]

sshortcircuit - 2013-07-19 11:11 PM

 

"and you have another fan running disturbing" Well my inverter does not have a fan so it has to be more efficient. It would be really interesting if somebody had the actual facts and figures to compare an inverter to a dc to dc converter as whatever you do you get nout for nout.

 

Thats a pity, I've often wondered if I could charge my leisure batteries using mine hooked up to a battery charger :D

[BGD]

sshortcircuit - 2013-07-20 12:11 AM

 

"and you have another fan running disturbing" Well my inverter does not have a fan so it has to be more efficient. It would be really interesting if somebody had the actual facts and figures to compare an inverter to a dc to dc converter as whatever you do you get nout for nout.

 

 

Eaxactly.

Anyone who read my earlier post would have ( hopefully) gathered that it's the EFFICIENCY issue which is exercising my mind on this; and that was the point.

 

 

I invite anyone who is still banging on about "use an inverter" to actually read my earlier posts.

 

 

 

My proposition was that it should be more efficient to use a simple 12 volt DC to 19volt DC step-up transformer, simply plugged into a ciggie socket, rather than go the much more complex inverter route of 12 volt DC to 220 volt AC then back to 19 volt DC.

 

I await guidance from any qualified or knowledgeable people as to whether this simpler route will save valuable leisure battery reserves if we are using the laptop for 3 or 4 hours a night, and not on mains hookup.

 

Where's Clive Mott et al when you need them!

[Guest 1footinthegrave]

I'd have thought considering you have lots of sun on the costa's, a solar panel would be a must have, fully charged batteries to last you all night long,then what would be the problem using your inverter,after all a laptop power brick is hardly a big load, I've used that setup for some years ( though without a solar panel to charge the leisure batteries ) and it's hardly touched the batteries, yes of course you lose some efficiency with its use, but as for the efficiency of the 12v up to 19 volt, or using the inverter perhaps a post here might get you a definitive answer, worth a punt, ;-) post up the answers here if they can do the business, I'm sure others would be interested.

 

http://www.electriciansforums.co.uk/

[Antonio]

http://www.ebay.co.uk/itm/330588852803?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 (?)

[Robinhood]

BGD - 2013-07-20 10:00 AM

 

 

I await guidance from any qualified or knowledgeable people as to whether this simpler route will save valuable leisure battery reserves if we are using the laptop for 3 or 4 hours a night, and not on mains hookup.

 

 

....the answer is that using the DC to DC convertor will almost definitely save you battery power (over the option of using an inverter and the laptop power supply).

 

Whether the amount is valuable or not, however, depends very much on the nature of the equipment you are using, and the amount of time it is used for.

 

Some generalities may help to illustrate:

 

A general purpose inverter, such as is regularly utilised by motorcaravanners, is unlikely to exhibit an efficiency of greater than 80% (and then only at close to rated output). Hence, every 80W you take out, you have to put 100W in.

 

If you then add your normal (240v) laptop lead, then this typically might exhibit 85% efficiency.

 

So, if you have a laptop with a (not uncommon) nominal 70W requirement, the 70W at the laptop will require 70/0.8*0.85 W from the source (roughly 103W). (This assumes, of course, that the device is running all the time at its nominal consumption)

 

If instead you use a decent DC to DC switched mode supply, you may be lucky enough to get up to roughly 95% efficiency (especially if it is specifically sized for the demand), but for illustration, lets assume 90%. Hence, the nominal 70W requirement would require 70/0.90 W from the source (under 78W).

 

The difference in demand in this case would be 25W, leading to 100Wh for 4 hours a night of watching. At a nominal 12.7V from a fully charged battery, this would be 100/12.7, or a saving of something under 8Ah per night.

 

E&OE

 

;-)

 

 

[BGD]

Many thanks Robinhood.

 

That's just the sort of answer I was really trying to establish.

 

We go away for quite extended periods in the MH (maybe 4 to 8 weeks away per trip), throughout the year...including winter months when even in Spain/Portugal it can be very cloudy/raining a lot.....and we are often parked up for maybe a week or so at a time, thus not running the engine, but reliant on just solar panels to replenish our daily/nightly use of 12 volt usage.

 

 

 

So, given that order of leisure battery power saving, I do think that getting one of those DC-to-DC ciggie lighter socket adaptors for about 15 quid is the way to go for us.

 

Then our existing inverter can continue to be used for other short-burst mains power when needed (electric razer etc), and would remain available as backup for the laptop TV watching if the DC adaptor packed up.