17VDC PSU FOR NOTEBOOK

[Simon Mason]

Rod Speed's idea in action.

[Bob Minchin]

As you are both prolific posters here, I'm having trouble locating the text details of Rods idea. It looks useful Could you link to it please?

TIA

Bob

[Tim+]

Why not just read the name off the top?

Tim

[Simon Mason]

Yes, it is fantastic and means that I can work on my Acer Aspire S7 all day long with no mains power and at full screen brightness.

Well done Wodders.

[Simon Mason]

Just bought another one for the car as you can pump up tyres with it and start engines with a flat battery.

[The Natural Philosopher]

Ah. wodders is pleasuiring himself again.

[Bob Minchin]

The spec for the G7 says 3.5 amps at 19v. What does your laptop require? My Dell says it needs it needs 19v at 4.62 amps (which I find hard to believe) but would make this unit to be inadequate for the job.

[Andy Burns]

I have a handy Dell travel adapter that is very small, takes any voltage you're likely to find in offices, hotels, cars and planes, it's 60W which was the same as the power brick of the laptop I had at the time.

Two laptop upgrades later, each comes with larger and heavier chargers now 130W or more, which I leave connected to docking stations at home and in an office.

Dell laptops will accept under-powered adapters (you might get a warning at boot which you override) it can only charge slowly if it's running at the same time, and it threatens to throttle the CPU or switch from the Radeon to the Intel GPU, but typically it takes under 20W in use, so for travel use the 60W adapter is still great.

[Simon Mason]

It only needs to last whilst I am on the ferry or train, as soon as I get to my cabin or hotel, I can plug into 240VAC again.

[Judith]

Has someone f***ed up the mains supply with their d-i-y electrics then.

[Judith]

Oh - I thought you were having to use it in the house because the electrics were f***ed again.

You must make an awful lot of trips on ferries and trains to need that.

Do you have a very long daily commute?

[Judith]

Why not keep the first one in the car - and then take it with you on your thousand mile daily commute using trains and ferries which necessitated the device?

A fool and his (loads of) money are soon parted.

If we believe you of course.

[Bob Minchin]

I'm not concerned about the running time but more about the potential overload of the SMPSU in the Suaoki G7. If it is rated at 3.5amps and the lappy wants 4.62 amps there could be a problem. There are vids on YouTube where the dc jack output seems to have failed but the usb and car start still work. However I suspect the Dell spec if for running the laptop AND charging so I could easily disconnect the battery from the laptop.

[Bob Minchin]

Yes I have one of those. Maybe using it and the Suaoki G7 (bodged onto the 12v car start output connector) would be a solution for running the laptop and charging it. The Suaoki G7 claims 66.6Wh and my lappy battery is 68Wh so with conversion losses the Suaoki G7 is going to be less effective than carrying a second battery for the Dell.

[whisky-dave]

Why it's just run at 3.5amps which it is rated at, unless it's a bit crap then there might be problems. It will just charge a little slower I suppose.

[Simon Mason]

You should know my commute by now.

[Bob Minchin]

Well not necessarily if the load it too great, it depends how the source behaves. ie goes into constant current and drops the voltage, tries to deliver the current and damages itself, or uses foldback current limiting as many SMPSU do and turns itself off or right down until the load impedance increases. HOWEVER.....

I've subsequently found that the dell will only charge from a legit dell power supply which has a chip in it that identifies the charger capacity and the laptop alters the charging regime accordingly. No ID chip = no charge delivered. So the issue goes away! The lappy itself draws around 20-30w according to how hard it is working, display brightness etc.

[T i m]

I've repaired many a Dell charger when the centre pin / sense wire has broken somewhere (typically, in the cord as it leaves the PSU or enters the back of the DC jack) by shortening (if at the PSU end) or replacing the cable with a new one. I only do this for myself but if you like doing such things it's often a much cheaper way to get a 'good' charger again (I just crack the seam on the PSU open with a toffee hammer with the PSU held in my hand and when glued back together afterwards you would never know it had been opened).

It is 'clever' how the laptop (inc BIOS) 'knows' what spec the charger is but not so good when it won't work even when the charger itself it working.

Similarly 'clever' how phones they can go into fast charging mode and take the USB output voltage over 5V (I've seen it as high as 9). ;-)

Cheers, T i m

[Andrew]

and at full screen brightness.

The reviews on Amazon say otherwise. One reviewer only managed 105 minutes powering his laptop.

[Simon Mason]

Internal is 2 hours + 105 mins = 3.75h = plenty.