Notebook Power Supply Question

Chromaflage · 03-16-2008, 09:41 PM

My power supply for my notebook just gave up. It's output rating is 18.5 Volts. I have an extra power supply with the same plug and polarity, but it's 19 volts. Will I have any problem using the backup even though it's output is .5 volts higher?

ampersat · 03-17-2008, 06:06 AM

I'm thinking someone like Gus would be a good person to answer your question, but my question is - what's your laptop worth to you? I wouldn't think that .5 volts would matter but it might.

Chromaflage · 03-17-2008, 07:39 AM

Ummmm...that's why I asked, Doug.

Troutinator · 03-17-2008, 07:57 AM

Should not matter at all. The PS does not directly supply the circuitry, it goes through a number of converters/regulators to supply the actual voltages to the end cicuit. Typical would be +/-12VDC, +5VDC, +3.3VDC...etc. I cannot imagine any decent laptop not having sufficient deratings applied to the entry circuits to not be able to handle an additional 3%. We design witha 40% overhead margin on our power entry circuits...

JustCallMeDave · 03-17-2008, 08:22 AM

I wouldn't take the risk myself.

Undertaker · 03-18-2008, 12:46 PM

Quote:

Originally Posted by Chromaflage

My power supply for my notebook just gave up. It's output rating is 18.5 Volts. I have an extra power supply with the same plug and polarity, but it's 19 volts. Will I have any problem using the backup even though it's output is .5 volts higher?

Sounds like HP/Compaq voltage.
I have a couple of the HP variety if they will work for you. Both 90 watt docking station version and 65 watt standard. I use the docking station version on my HP laptop all the time with no problems.

fishbait · 03-18-2008, 01:03 PM

Should not matter at all.

Gus Orviston · 03-18-2008, 09:08 PM

The specs for notebook voltage inputs are quite loose. that is there is a required mininim and that is about 16.5 V and the max I have seen for 15 years is about 20-21v. the cell configuration drives the input voltage. so it might not apply to the smaller notebooks that might have cells in a 2x3 config. but if you supply states 18.5v.. then 19v should be no issue at all.

Make sure you got a good connection and new supply can support about 85W,, or whatever the old one said.

While this doesn't feed right into the main circuit...ala cpu... the regulator is coupled closely or right on the motherboard.. so blowing it is not a good thing. it would render the NB dead regardless.

The Power comes into a 1st stage regulation that drives the battery charging circuit and then regulated down to 1.5V and other 3V rails in the system. As well as all the other rails for communcations etc...

gus

Chromaflage · 03-18-2008, 10:23 PM

That's exactly what it is. 18.5 volts/65 Watts. Small (yellow) plug to computer.

Quote:

Originally Posted by Undertaker

Sounds like HP/Compaq voltage.
I have a couple of the HP variety if they will work for you. Both 90 watt docking station version and 65 watt standard. I use the docking station version on my HP laptop all the time with no problems.