ac adapter and wattage for notebook computer

Drew · Joined: 05 Aug 2007 Posts: 73

Hi Gang:

On a friend's Compaq notebook that calls for a 90W power adapter (the
AC Adapter connector has 90W labeled above it), he is using an HP AC
Adapter that is 75W.

Is this safe to do or could it damage the notebook? I wasn't sure
since the wattage on the power supply is lower than what the notebook
wants?

Is this safe or a big no no?

Drew

Archived from group: alt>certification>a-plus

G.G. Willikers · Joined: 30 Jan 2008 Posts: 8

Drew wrote:
> Hi Gang:
>
> On a friend's Compaq notebook that calls for a 90W power adapter (the
> AC Adapter connector has 90W labeled above it), he is using an HP AC
> Adapter that is 75W.
>
> Is this safe to do or could it damage the notebook? I wasn't sure
> since the wattage on the power supply is lower than what the notebook
> wants?
>
> Is this safe or a big no no?
>
> Drew

it will work, but the battery will never get optimally charged.

Ebay is your friend.

--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom

John O · Joined: 06 Feb 2008 Posts: 9

>
> Is this safe or a big no no?

It's not a "big" no-no, but it's probably not dangerous, either. Just make
sure the power supply doesn't overheat...give it room to let off any heat.
Best not to run the machine at full power (bright display and heavy CPU
load) while working with a dead battery too. Ummm, if the supply doesn't
ever get hot then this is probably a big non-issue anyway.

Of more importance is the voltage. What's the output voltage of the two
supplies? They should be the same, or very close.

If it's been used this way for a while, no problems, then it'll probably
work for the life of the laptop.

-John O

John O · Joined: 06 Feb 2008 Posts: 9

>
> but the battery will never get optimally charged.

Drew didn't provide enough info to be able to say that with any
certainty...unless you know that all HP supplies have a lower voltage
compared to Compaq supplies. Smile

-John O

G.G. Willikers · Joined: 30 Jan 2008 Posts: 8

John O wrote:
>> but the battery will never get optimally charged.
>
> Drew didn't provide enough info to be able to say that with any
> certainty...unless you know that all HP supplies have a lower voltage
> compared to Compaq supplies. Smile

>
>
My EXPERIENCE as a laptop technician and having read the MANUALS
regarding this subject give credence to my answer.

HP makes all sorts of power supplies. So does Compaq. Belive it or not
they can be cross compatible.

His problem is that he does not have the 90W power supply that goes with
his laptop. He wanted to know if using a lesser 75W adapter would be
detrimental to his laptop.

The answer is NO, it will not harm it.

And to further add info to this, I do believe at power up the HP laptop
will actually display a warning message about using a lesser power
supply and the battery not being charged optimally.

So John O, before you go leaping off the bridge make sure you know what
your talking about. Smile

--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom

John O · Joined: 06 Feb 2008 Posts: 9

>
> So John O, before you go leaping off the bridge make sure you know what
> your talking about. Smile

Yeah.

So, does a lower max power mean the supply has a lower output voltage or
that it can provide comparatively less current at the same or even a higher
voltage? The power rating of a supply is meaningless by itself, and your
answer to Drew may be invalid or accurate depending on the answer to this
question. And you can't answer this question unless you have more info from
Drew than I have so far.

IOW, it's not me who's leaping. Smile

-John O

G.G. Willikers · Joined: 30 Jan 2008 Posts: 8

John O wrote:
>> So John O, before you go leaping off the bridge make sure you know what
>> your talking about. Smile

>
> Yeah.
>
> So, does a lower max power mean the supply has a lower output voltage or
> that it can provide comparatively less current at the same or even a higher
> voltage? The power rating of a supply is meaningless by itself, and your
> answer to Drew may be invalid or accurate depending on the answer to this
> question. And you can't answer this question unless you have more info from
> Drew than I have so far.
>
> IOW, it's not me who's leaping. Smile

>
> -John O
>
>
>
>
>

He states that he has a 75W HP PSU.
He says he has a 90W HP laptop.
He says he's worried that the 75W PSU will damage his laptop.
Based on this information and being quite familiar with HP products,
especially laptop repair, I am confident that my answer is adequate to
the question posed.

--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom

Mister · Joined: 06 Feb 2008 Posts: 2

Wow! Soon the ruler will be out to measure!

I have used a smaller wattage PSU on a laptop already and the only
thing that happened was the battery never fully charged and the PSU
got a little bit hotter.

Now, the only place I am leaping is for another Jack and Coke!

Fixing computers sober is no longer a challenge! Heh! Heh! Heh!

On Tue, 12 Feb 2008 03:03:11 GMT, "G.G. Willikers"
wrote:

>John O wrote:
>>> So John O, before you go leaping off the bridge make sure you know what
>>> your talking about. Smile

>>
>> Yeah.
>>
>> So, does a lower max power mean the supply has a lower output voltage or
>> that it can provide comparatively less current at the same or even a higher
>> voltage? The power rating of a supply is meaningless by itself, and your
>> answer to Drew may be invalid or accurate depending on the answer to this
>> question. And you can't answer this question unless you have more info from
>> Drew than I have so far.
>>
>> IOW, it's not me who's leaping. Smile

>>
>> -John O
>>
>>
>>
>>
>>
>
>He states that he has a 75W HP PSU.
>He says he has a 90W HP laptop.
>He says he's worried that the 75W PSU will damage his laptop.
>Based on this information and being quite familiar with HP products,
>especially laptop repair, I am confident that my answer is adequate to
>the question posed.

John O · Joined: 06 Feb 2008 Posts: 9

>
> He states that he has a 75W HP PSU.
> He says he has a 90W HP laptop.
> He says he's worried that the 75W PSU will damage his laptop.
> Based on this information and being quite familiar with HP products,
> especially laptop repair, I am confident that my answer is adequate to the
> question posed.

Confidence is a good thing, but you can't fix much with logic like that.
Good luck to you.

-John O

G.G. Willikers · Joined: 30 Jan 2008 Posts: 8

John O wrote:
>> He states that he has a 75W HP PSU.
>> He says he has a 90W HP laptop.
>> He says he's worried that the 75W PSU will damage his laptop.
>> Based on this information and being quite familiar with HP products,
>> especially laptop repair, I am confident that my answer is adequate to the
>> question posed.
>
> Confidence is a good thing, but you can't fix much with logic like that.
> Good luck to you.
>
> -John O
>
>
>
3000 refurbished / imaged / donated last year, I think I can handle it.

--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom

Barry Watzman · Joined: 05 Aug 2007 Posts: 801

More to the point, I think we can say with certainty that he's wrong.
The battery will charge fine, but it may take longer to get there.

John O wrote:
>> but the battery will never get optimally charged.
>
> Drew didn't provide enough info to be able to say that with any
> certainty...unless you know that all HP supplies have a lower voltage
> compared to Compaq supplies. Smile

>
> -John O
>
>

Barry Watzman · Joined: 05 Aug 2007 Posts: 801

And I do believe you are wrong.

Only Dell does anything like this, and they complain because, and only
because, it's not a Dell supply. Regardless of the electrical
characteristics of the supply, which may be an exact match for what the
laptop needs.

G.G. Willikers wrote:

>
> And to further add info to this, I do believe at power up the HP laptop
> will actually display a warning message about using a lesser power
> supply and the battery not being charged optimally.

Barry Watzman · Joined: 05 Aug 2007 Posts: 801

We have to assume that the voltage ratings are the same, or at least
within 10%. Using a supply with the wrong voltage (more than 10% off)
usually just won't work.

So a lower wattage rating really just means a lower [Maximum] current
rating.

John O wrote:

>
> So, does a lower max power mean the supply has a lower output voltage or
> that it can provide comparatively less current at the same or even a higher
> voltage? The power rating of a supply is meaningless by itself, and your
> answer to Drew may be invalid or accurate depending on the answer to this
> question. And you can't answer this question unless you have more info from
> Drew than I have so far.
>
> IOW, it's not me who's leaping. Smile

>
> -John O
>
>
>
>
>

G.G. Willikers · Joined: 30 Jan 2008 Posts: 8

Barry Watzman wrote:
> And I do believe you are wrong.
>
> Only Dell does anything like this, and they complain because, and only
> because, it's not a Dell supply. Regardless of the electrical
> characteristics of the supply, which may be an exact match for what the
> laptop needs.
>
>
> G.G. Willikers wrote:
>
>>
>> And to further add info to this, I do believe at power up the HP
>> laptop will actually display a warning message about using a lesser
>> power supply and the battery not being charged optimally.

You know I couldn't exactly remember whether I read it on the site or on
a screen.

I work with so many different makes and models it is hard to keep track.

--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom

smackedass · Joined: 05 Aug 2007 Posts: 192

>
> Only Dell does anything like this, and they complain because, and only
> because, it's not a Dell supply. Regardless of the electrical
> characteristics of the supply, which may be an exact match for what the
> laptop needs.

This may sound like a stupid question, but does the form factor/size of the
charging pin constitute any difference?

smackedass

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