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Drew
Guest
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 Posted: Mon Feb 11, 2008 9:50 pm Post subject: ac adapter and wattage for notebook computer |
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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 |
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G.G. Willikers
Guest
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| Posted: Tue Feb 12, 2008 1:24 am Post subject: Re: ac adapter and wattage for notebook computer |
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Drew wrote:
| Quote: | 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
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it will work, but the battery will never get optimally charged.
Ebay is your friend.
--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom |
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John O
Guest
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| Posted: Tue Feb 12, 2008 1:26 am Post subject: Re: ac adapter and wattage for notebook computer |
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| Quote: |
Is this safe or a big no no?
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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 |
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John O
Guest
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| Posted: Tue Feb 12, 2008 2:02 am Post subject: Re: ac adapter and wattage for notebook computer |
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| Quote: |
but the battery will never get optimally charged.
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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. :-)
-John O |
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G.G. Willikers
Guest
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| Posted: Tue Feb 12, 2008 4:30 am Post subject: Re: ac adapter and wattage for notebook computer |
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John O wrote:
| Quote: | 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. :-)
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. :)
--
The RIGHT REVEREND G.G. WILLIKERS
(formerly) Monsignor Boddom |
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John O
Guest
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| Posted: Tue Feb 12, 2008 7:37 am Post subject: Re: ac adapter and wattage for notebook computer |
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| Quote: |
So John O, before you go leaping off the bridge make sure you know what
your talking about. 
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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. :-)
-John O |
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G.G. Willikers
Guest
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| Posted: Tue Feb 12, 2008 9:03 am Post subject: Re: ac adapter and wattage for notebook computer |
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John O wrote:
| Quote: | So John O, before you go leaping off the bridge make sure you know what
your talking about. :)
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. :-)
-John O
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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 |
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Mister
Guest
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| Posted: Tue Feb 12, 2008 10:10 am Post subject: Re: ac adapter and wattage for notebook computer |
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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" <noone@youknow.com>
wrote:
| Quote: | John O wrote:
So John O, before you go leaping off the bridge make sure you know what
your talking about. :)
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. :-)
-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. |
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John O
Guest
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| Posted: Tue Feb 12, 2008 7:07 pm Post subject: Re: ac adapter and wattage for notebook computer |
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| Quote: |
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.
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Confidence is a good thing, but you can't fix much with logic like that.
Good luck to you.
-John O |
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G.G. Willikers
Guest
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| Posted: Wed Feb 13, 2008 1:38 am Post subject: Re: ac adapter and wattage for notebook computer |
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John O wrote:
| Quote: | 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 |
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Barry Watzman
Guest
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| Posted: Mon Feb 18, 2008 12:31 pm Post subject: Re: ac adapter and wattage for notebook computer |
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It's unlikely to be dangerous. The power supply should shut down if an
attempt is made to draw too much power (the alternative would be to
overheat to the point of being a fire hazard, but I'll assume it's a UL
certified supply). However, the only time the laptop would draw it's
max load would be if it was doing EVERYTHING at once .... charging the
battery, running a worst case CPU load, burning an optical media,
running a max load peripheral on every USB port, accessing the hard
drive with a worst case seek pattern .... all at once. The reality is
that most laptops draw far less than their rated power requirement (like
half), AND most power supplies can put out more than their rated load
(at least 10% to 25% more). So while it's not a good idea ... the
supply may run hot ... it's not truly dangerous, either.
Drew wrote:
| Quote: | 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 |
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Barry Watzman
Guest
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| Posted: Mon Feb 18, 2008 12:32 pm Post subject: Re: ac adapter and wattage for notebook computer |
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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:
| Quote: | 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. :-)
-John O
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Barry Watzman
Guest
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| Posted: Mon Feb 18, 2008 12:33 pm Post subject: Re: ac adapter and wattage for notebook computer |
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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:
| Quote: |
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. |
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Barry Watzman
Guest
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| Posted: Mon Feb 18, 2008 12:35 pm Post subject: Re: ac adapter and wattage for notebook computer |
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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:
| Quote: |
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. :-)
-John O
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G.G. Willikers
Guest
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| Posted: Tue Feb 19, 2008 5:13 am Post subject: Re: ac adapter and wattage for notebook computer |
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Barry Watzman wrote:
| Quote: | 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.
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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 |
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