12v power t/former for lappy (car plug)

[Louwai]

All,
I need to be able to run the lappy from my 12v batteries.
Can anyone recommend a car charger / power plug to supply power to the lappy. And where to get it from........


I've tried running my existing 240v power supply from my inverter, but it just doesn't work. Don't know why. I'm not an electronics expert........


Can anyone recommend one???


Cheers, B

[erick]

Bryan

This is the one you want - from Jaycar Cat #MP3463

http://www.jaycar.com.au/productView.asp?ID=MP3463&CATID=27&form=CAT&SUBCATID=665

$39.95 listed - sometimes on special. I have one to run the IBM lappy from a 12V car battery.

First check your power brick for your lappy - what are the output volts and amps?

Eric

[erick]

An inverter should work - but cheapies have very rough output - the laptop powerbrick might make some funny noises in operation!

But, why go 12VDC --> 240VAC --> XVDC? Cut out the middleman!

[Louwai]

Thanks Eric. For some reason this one didn't come up in the searches I did.

I hear you with the inverter, but I figured that I already had the inverter, (Scott gave it to me before he left) so I may as well try it that way first.


Just called the local Jcar & they have 7 in stock. Might slip over at lunch time.

[mithrandir]

Does it come with all the right plugs for all the different laptops? My T40 and T400 have different voltages and different plugs. The Targus power brick has all the plugs and auto voltage setting but is seriously more expensive.

[Merlin66]

I have three of these 12V>24V transformers.
One set at 15V for the HEQ5, one at 18V for the Lx200 and the other driving the Acer Laptop at 19V.
No issues so far.


Ken

[Louwai]

Just got a chance to check Eric.

The unit you've noted is a max output of 3.5a @15v
My lappy is a Toshiba Tecra & requires 6a @15v.

JayCar do have a larger model which will do the job. Is $about $80 I think.

B

[Merlin66]

Just re-checked mine....
Sorry, the ones I currently use came from Maplin's in the UK.
Model #L40BB, 120W Laptop Car Power Supply
Input: 12-16V 11.5A max
Output: 15/16/18/19/20V DC 6A
22/24V DC 5A

Sorry for the mistake.

Ken

[erick]

Just checked Bryan, and the 3.5A one drives my IBM lappie OK @16 V - but it is a light power user. In the field I have it set to spin down the drive quickly and always have the screen on low brightness behind its red perspex.

Just checked the IBM power brick and it is spec'd for 16V@4.5A out.

I'm pretty certain I put an ammeter in the circuit at some stage to check amps required so must have convinced myself the 3.5A inverter would be OK.

[Louwai]

I do the same Eric. I have it at absolute minimum pwr usage to get the max out of the battery.

This item we're talking about will be plugged into my 12v system (2 x 100ah batteries) so I want it to be absolute minimum pwr drain as well.

Last thing I want is to run out of power at around 2am:mad2:

[Manav]

Since we are on the topic just a quick one my Toshiba A300 requires 19V 6.32A and I have a Diamec 12V 26AH Gel battery. Will that work?

[mswhin63]

I use this one:

http://www.altronics.com.au/index.asp?area=item&id=M8627

Up to 6A

[erick]

I would expect that putting 12V into the laptop which requires 19V won't work, sorry. You will need a DC-DC inverter along the lines of the ones we have been discussing. It looks like the inverter in post #12 (thanks Malcolm) will suit your laptop nicely - but check whether it has the right plug tip.

Once you have the voltage right, then you can think about current. Now if your laptop is really drawing 6A @ 19V, then expect the inverter be drawing 9.5 or 10A from the 12V battery. You'd be lucky to get two hours out of your 26AH battery. :sadeyes:

You may have to work with your laptop settings to reduce that curent draw. As Bryan and I were discussing, set any disk drives to spin down after a short delay. Run screen at low brightness. Remove as many power loads as you can. Eg, use touchpad rather than an external mouse etc.

[mswhin63]

Need to take in factors that may arrise in using the correct adaptor, so 3.5A may work but has not headroom, whereas a higher will have a better opportunity to cver variations that MAY occur.

[wmzaphod]

I have the larger model, works very well and came with all the connectors and voltages for all my laptops (I have 5..).

Also, it's much more efficient to use one of these rather than an inverter and the standard power supply. :thumbsup:

Cheers.....

[Louwai]

Well I went & got the bigger one.
Puts out 8amps at 15v.

Hooked it all up & it works a treat.
With the lappy set on "Full Power" & no battery inserted,
- While booting up it was drawing just on 4amps.
- While running The Sky 6 it was drawing 2amps.
- With the lappy shut down & the battery inserted (effectivly charging the battery) it was drawing approx 1.8amps.


The scope on full slew & with all the heaters working draws about 2.5amps.
So with the lappy set down to minimum pwr usage & the scope as well I should be drawing around the 4amps max.

So with the 2 x 100ah batteries I should get at least 25 to 30hrs of good power.

It's all coming together......:)

[Manav]

:sadeyes:

I'll try to disable devices and see if I can draw less current. I guess 2hrs is better than 0hrs.

[wmzaphod]

There are heaps of things you can do to minimise power use and increase efficiency......

One thing I forgot to turn off early on was the networking, wireless and the cabled port and don't forget the blue tooth. Turn off any background processes like auto updates (any updates)....

I'm also running some tests to see if it's better to charge the laptop using the 12v - 19v converter and run from the battery orrrrrr, run the laptop continually from the converter :shrug:

[mswhin63]

Most laptops have power saver option that can be enable in the battery configuration, should be enough. In most cases it should be the batteries used that match the power requirements.

[MrB]

Bryan, you'll be happy to know that at my store atleast(open 14months), we have never had a single one of those MP3472 supplies returned.
They're great supplies, I have the smaller one.
You have a 1 year warranty anyway, so hold on to the receipt.