HP Laptop AC Power Supply

Check Radio Shack! They have a line of AC/DC Wall Supplies with interchangeable tips. I would buy the tip you need and solder it on to your supply!

My problem is, does the center pin serve a function.

From my understanding, the center pin is used by the charger to prevent over charging during the latter stages of the charge cycle. Once the charger sees a nearly charged battery, it reduces the current to more efficiently "peak charge" the laptop battery.

Some A-hole companies like to make devices that only work with their supplies. Like my cell phone for example, will say "unauthorized charger!!!" and won't charge. The previous poster sounds right, but it wouldn't surprise me if there are a few laptops that do that too. Most laptops I've seen still only have two contacts, so there might be something for testing if it is a "genuine HP adapter" or whatever.

Nick

My phone said that once, found out that the output polarity on the aftermarket charger was switched. That's what I get for going discount when I have a $400 phone.

Could I damage the Laptop or the Laptop battery if I simply go ahead and ignore this third contact.

See if you can use a volt meter to confirm which one is what voltage. Be careful to not short out the supply with the volt meter leads, it's surprisingly easy to do that with some of these plugs...

Then like the other poster said, contact HP if you can do use non standard supplies. If they say that you can't, make sure you make it sound like you won't do it before you hang up, so they don't record down that you voided the warranty. Then if you actually have a problem...... But if you're lucky, you might get a real helpful tech, that tells you what that third pin does.

After that, go ahead and try it. If you get really close to the actual voltage output of the HP supply, there's no reason it should hurt it... Everything is so regulated in computers, it should be fairly forgiving as long as you are within 5%. I was using a power supply for my laptop that was from a samsung monitor I think (plugged into the docking station). It was rated for the same voltage and amperage, but the battery never completely charged to 100% (because it wasn't as perfectly regulated, and wasn't exactly 16 volts, like the IBM supply was). Switching between the IBM and hacked up supplies, confused the power management software a little, and made it a kinda really inaccurate (like it said it had greater capacity than it was designed for, making it give way to much estimated time left).

So, if you are careful, you shouldn't be able to hurt anything. If your new adapter is higher quality than the one I used, I doubt you will even have problems with the power meter being off. And it's very rare, that not hooking power to something damages it, but it's always good to be careful, so you could try hooking power to one and not the other to see what works (determined with the volt meter on the original adapter).

Hope my talk is more than useless babble

I would ask HP first, they will probably tell you that using a modified "run of the mill" charger will void your warranty on the battery and the laptop. I would buy another HP charger and run it from an an inverter if you need a mobile spare.

Thanks for all suggestions. Will keep you informed of what happens

As somebody already said some laptop supplies and even mobile phone chargers - in fact any type of electronic powers supplies have progressed beyond the straight two wire 14Vdc charge.

Obviously an un-regulated power supply could not supply the full 14Vdc that would be required to power the laptop and charge the battery at the same time, if you were connected to a laptop with a flat battery, without roasting the battery during normal trickle charge conditions.

With very basic regulated supplies the third or multiple connection is used to provide the full "boost " charge if you like with the other connection and the common used to supply the regulated trickle charge and counteract the dry cell memory effect.

You will not be abale to measure differences at the open pins as it charger needs to be connected to the battery in order to monitor load conditions and switch accordingly.

It all depends on how sophisticated your charger is, but as rule of thumb if it has the third connection then it is most likely connected and used for a purpose.