Laptop DC Power Plugs

[Hydrozoan]

I use a universal DC-DC ‘brick’ to power my laptop from the boat’s DC supply – in fact I am already on my second brick, as the first was too low powered for the first replacement laptop.

Now, having just changed again to a new (HP/Compaq 15-s101na) laptop, I find the power of the brick adequate but the interchangeable power plug set it came with does not have a tip to fit the Compaq.

Is there anywhere one can get laptop power plugs with simple wire tails?

 

[Giblets]

Have you tried contacting the manufacturers of the "brick"? They may be able to supply a suitable tip.

 

[pvb]

If you measure the extranal and internal diameters of the plug, you should be able to buy a matching plug easily. Compaq used to use 5.5/2.5mm plugs, I know because I cannibalised an old Compaq charger to make a DC charging lead for my Torqeedo outboard.

 

[knightvision]

For quite some time I've been using the kensington wall/Auto/Air adapters. They work with a variety of laptops and provide USB charging as well. Yes not cheap.. But reliable and provide consistent behaviour
http://www.kensington.com/en/gb/4470/33403eu/wall-auto-air-laptop-power-adapter-usb

 

[RichardS]

For quite some time I've been using the kensington wall/Auto/Air adapters. They work with a variety of laptops and provide USB charging as well. Yes not cheap.. But reliable and provide consistent behaviour
http://www.kensington.com/en/gb/4470/33403eu/wall-auto-air-laptop-power-adapter-usb

Some of the HP / Compaq DC plugs are very unusual so I've been through this. From memory I think 7.4mm OD but with three connections. Outer connector, inner connector and centre pin. Some Dells also use the same connector but without the centre pin. The centre pin is designed to ensure that you can only use genuine HP / Compaq bricks!

If you search the internet there is a way to bypass the centre-pin check with a capacitor or something, but in the end I gave up and stuck to using an inverter with the HP brick even though I did eventually find a suitable tip for my 12V step up transformer which worked with my Son's Dell but not my HP

My HP is an excellent laptop but when it expires I will not buy another one unless they have dropped this silly practice.

Richard

 

[VicMallows]

Some of the HP / Compaq DC plugs are very unusual so I've been through this. ............................
If you search the internet there is a way to bypass the centre-pin check with a capacitor or something,

A resistor of about 170kohm (not critical) from the centre-pin to positive.

The rather unusual tip CAN be sourced on-line from the US, but it is actually cheaper to buy the cheapest replacement mains charger on ebay (under£5) and chop off the lead! You can always use the PSU for something else. A few multi-adapter kits DO contain the correct tip, but you will probably have to open the tip up in order to make a connection to the centre-pin.

 

[Hydrozoan]

Thanks to you all.

I was thinking of a small inverter as a fall back, as Richard suggests, but would prefer the neatness of the brick so Vic's idea attracts.

Just one question for Vic or Richard: if one chops off the lead, does one have to put a 170kohm resistor in the wire, across the centre pin and positive leads, or is that resistor in the socket within the laptop? (The plug is much less than 7.4mmOD, BTW, and over 1cm long.)

 

[Hydrozoan]

I posted that last too late at night , for on reflection I see that the resistor would not be in the socket, and I presume it would have to be put in the lead as it would not be present in a universal power brick (but would be in a Compaq-specific power supply). I also presume that it could be 'tapped off' the positive lead just before the plug and led to the third, 'pin' wire in the plug.

But I should be grateful for confirmation of that - or the right procedure if I'm still not getting it. Thanks.

 

[RichardS]

I posted that last too late at night , for on reflection I see that the resistor would not be in the socket, and I presume it would have to be put in the lead as it would not be present in a universal power brick (but would be in a Compaq-specific power supply). I also presume that it could be 'tapped off' the positive lead just before the plug and led to the third, 'pin' wire in the plug.

But I should be grateful for confirmation of that - or the right procedure if I'm still not getting it. Thanks.

I didn't do it but you are right that with a universal 12v power brick you would need to put the resistor in the tip or just before the tip. As you say, you can't put it in the brick itself because that will only have the -ve and +ve connections and a two core cable.

If you can indeed get one for £5, Vic's idea of buying an OEM spec mains brick and chopping the lead off sounds like a neat idea as the resistor must already be in the tip rather than in the mains brick as that would mean using a three core cable from the mains brick which would be a lot more expensive I guess.

Interesting you say that your plug is not the HP/Compaq 7.4mm version. It might be worth checking with a voltmeter that you do indeed have power to both the inner sleeve and the centre tip.

Richard

 

[VicMallows]

(The plug is much less than 7.4mmOD, BTW, and over 1cm long.)

I think RichardS and I may have caused you confusion. We were commenting specifically on the three-pin 7.4mmOD plug used on SOME HP/Compaq laptops. These have outer sleeve (-ve), inner sleeve (+ve), and a deeply recessed centre pin which is the one that needs the 170k resistor. [There is also a 7.9mm variant of this plug ..... don't know who uses it].

Other HPs use various other plugs. I have one which uses a two-wire 5.5mm OD with inner and outer sleeves, no pin. These are readily available, but again single price for one is usually extortionate, especially with postage.

 

[Hydrozoan]

Thanks to you both for the quick responses. My plug is ca. 4.5mm OD, but does have a central pin, so I'll investigate further - and perhaps end up using a small inverter as the 'least hassle' option!

It’s my measure of getting old, that upgrading ones PC is a pain rather than a pleasure. The last one ran under Vista, which (rather than its inherent power or memory) was increasingly a problem for the navigation software. So for that and more general reasons I changed, only to find this DC power problem – and the fact that the GPS puck does not support Windows 8.1, an OS which I don’t much like anyway.

Hey ho! Perhaps I should have taken a tablet …

Thanks again.

 

[Strolls]

Someone on these forums mentioned these guys a week or two ago: http://www.power4laptops.co.uk

They do a 12v charger for my Mac laptop for £45 - I couldn't find yours on there, but it might be worth giving them a bell.

 

[Hydrozoan]

Someone on these forums mentioned these guys a week or two ago: http://www.power4laptops.co.uk

They do a 12v charger for my Mac laptop for £45 - I couldn't find yours on there, but it might be worth giving them a bell.

Thanks very much for looking - I suspect that power pack makers take time to catch up with changes in PC design, so coverage of new models will be inevitably delayed. But worth giving them a call, I agree.

 

[knightvision]

Kensington have support for a wide range of laptops They give you power tips certified to work with them. There is a compatibility app here
http://www.kensington.com/en/ie/4688/laptop-power-charger-compatibility-checker

I currently use it with Fujitsu, HP, Panasonic and Dell equipment regularly. I simply change tips. It means I don't have thousands of charges I only need one..

 

[Hydrozoan]

Kensington have support for a wide range of laptops They give you power tips certified to work with them. There is a compatibility app here
http://www.kensington.com/en/ie/4688/laptop-power-charger-compatibility-checker

I currently use it with Fujitsu, HP, Panasonic and Dell equipment regularly. I simply change tips. It means I don't have thousands of charges I only need one..

Thanks - I've just used that tip compatibility checker and unfortunately my HP Compaq model number is not listed. Perhaps it will be in due course, and I may get in touch with Kensington and other suppliers to see if that is likely to happen soon. Thanks again for the link.

 

[Hydrozoan]

I've managed to track down:

(1) 'My' small plug with a connector to the larger (and older?) style HP plug:
http://www.ebay.co.uk/itm/DC-Plug-7...Dell-HP-Laptop-AC-Mains-Charger-/400790142020

(2) A repair kit version of 'my' small plug with a connection box:
http://quickfixdcplugs.miiduu.com/4...-for-hp-amp-dell-ultrabook-195v-333a-chargers

From the existence of (1) I am presuming that the small and large plug voltages (main DC and smart pin) are the same. I'll obviously try to confirm that - HP told me the main DC voltage is 19.5V, but they could not give me the smart pin voltage.

I doubt that my existing power 'brick' has the large plug from which I could bridge with (1) to the small plug, so I think my most direct solution is to get a power brick with the large plug, plus item (1) above.

Anyway, I thought I'd post the information in the hope that it may perhaps save someone else a fair bit of searching.

 

[RichardS]

I've managed to track down:

(1) 'My' small plug with a connector to the larger (and older?) style HP plug:
http://www.ebay.co.uk/itm/DC-Plug-7...Dell-HP-Laptop-AC-Mains-Charger-/400790142020

(2) A repair kit version of 'my' small plug with a connection box:
http://quickfixdcplugs.miiduu.com/4...-for-hp-amp-dell-ultrabook-195v-333a-chargers

From the existence of (1) I am presuming that the small and large plug voltages (main DC and smart pin) are the same. I'll obviously try to confirm that - HP told me the main DC voltage is 19.5V, but they could not give me the smart pin voltage.

I doubt that my existing power 'brick' has the large plug from which I could bridge with (1) to the small plug, so I think my most direct solution is to get a power brick with the large plug, plus item (1) above.

Anyway, I thought I'd post the information in the hope that it may perhaps save someone else a fair bit of searching.

Interesting finds. Thanks for coming back. One thing to be aware of is that I managed to a 12V power brick with the large 7.4mm plug. However, it did not have any connection to the centre pin so although I could use it with my Son's Dell, it still would not work with my HP. I think, from memory, it would power the HP but would not recharge the battery so it was not very useful. But this was all a couple of years ago so it's a bit faded now.

Richard

 

[theoldsalt]

Isn't it strange that despite laptops/netbooks being very mobile that manufactureres fail to supply or even offer 12v leads as well as 220v PSUs when so many of us would like to charge them in our cars which would make charging on a boat easy.
I really don't know how they can be truely called mobile devices if a 220v supply is needed to charge them.

 

[awol]

If you have one correct plug for the lap top, cut the wire, add connectors to the cuts and to your dc/dc supply - sorted!

 

[VicMallows]

If you have one correct plug for the lap top, cut the wire, add connectors to the cuts and to your dc/dc supply - sorted!

Effectively what was said back at post #5. Many people will though be understandably reluctant to interfere with their only known reliable supply , and would prefer to provide a completely separate new supply.