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Curiosity about battery chargers

Last response: in Laptops & Notebooks
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Anonymous
a b D Laptop
November 16, 2004 4:46:06 PM

Archived from groups: comp.sys.laptops (More info?)

What is the output form of a typical laptop charger? Is it full wave or
half wave rectification. Is it filtered or smoothed in any way?

No big deal. Just wondering.

Thank you.
Anonymous
a b D Laptop
November 16, 2004 11:44:25 PM

Archived from groups: comp.sys.laptops (More info?)

"Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>What is the output form of a typical laptop charger? Is it full wave or
>half wave rectification. Is it filtered or smoothed in any way?

They are all regulated DC voltages, from switching power supplies.
Anonymous
a b D Laptop
November 17, 2004 4:47:30 AM

Archived from groups: comp.sys.laptops (More info?)

It's DC.


Jack Gillis wrote:

> What is the output form of a typical laptop charger? Is it full wave or
> half wave rectification. Is it filtered or smoothed in any way?
>
> No big deal. Just wondering.
>
> Thank you.
>
>
Related resources
November 17, 2004 5:48:37 AM

Archived from groups: comp.sys.laptops (More info?)

William wrote:
> "Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>
>>What is the output form of a typical laptop charger? Is it full wave or
>>half wave rectification. Is it filtered or smoothed in any way?
>
>
> They are all regulated DC voltages, from switching power supplies.
>

I wouldn't have used the word "all", but your statement is mostly correct.

Problem is that it does not tell the whole story. And what's missing
can lead people to blow up their laptops.

There's "almost" always a current limit. In some cases that limit is
carefully controlled to limit the battery charge current. The result
is that if you stuff in a voltage with a significantly higher current
limit, you can make smoke. Even a supply with a lower limit may run the
laptop fine, but not suupply enough charge current to initiate charge
termination, thereby smoking the battery. Been there, done that.
Lithium chargers have other protections and MAY be immune to this
problem...maybe.

There's probably a sticker on the unit and a big sign in the manual that
says, "Use only with supplied AC adapter." It's there for a reason.
mike

--
Return address is VALID.
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Anonymous
a b D Laptop
November 17, 2004 9:21:45 AM

Archived from groups: comp.sys.laptops (More info?)

<William P.N. Smith> wrote in message
news:k6blp0tr1uk2oe9h67qjfbjhq4scofrto4@4ax.com...
> "Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>>What is the output form of a typical laptop charger? Is it full wave
>>or
>>half wave rectification. Is it filtered or smoothed in any way?
>
> They are all regulated DC voltages, from switching power supplies.
>

Thank you, William.

OK. That makes sense to me. Especially with Mike's follow on comment.

That leads to another question. Most, if not all Desktops have 4
voltages coming out of their power supplies, plus and minus 5v and plus
and minus 12v. For the most part the 12v are for drives, fans, etc. and
the 5v are for the IC's or whatever. Does everything inside a laptop,
drives and IC's run off of the one voltage, whatever it is, supplied by
the battery?

Thanks again.
Anonymous
a b D Laptop
November 17, 2004 10:58:49 AM

Archived from groups: comp.sys.laptops (More info?)

mike <spamme0@netscape.net> wrote:
>William wrote:
>> They are all regulated DC voltages, from switching power supplies.

>I wouldn't have used the word "all", but your statement is mostly correct.

You've actually seen an unregulated or linear laptop supply?

>There's "almost" always a current limit. In some cases that limit is
>carefully controlled to limit the battery charge current. The result
>is that if you stuff in a voltage with a significantly higher current
>limit, you can make smoke. Even a supply with a lower limit may run the
>laptop fine, but not suupply enough charge current to initiate charge
>termination, thereby smoking the battery. Been there, done that.
>Lithium chargers have other protections and MAY be immune to this
>problem...maybe.

Good point!

Note that the new Dell laptop bricks have what looks like a normal
barrel connector with two connections, but somehow the laptop can tell
the difference between the 70W and the 95W supply, and will refuse to
work with a non-Dell supply, so there's clearly some extra signalling
going on there...
Anonymous
a b D Laptop
November 17, 2004 11:01:23 AM

Archived from groups: comp.sys.laptops (More info?)

"Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>That leads to another question. Most, if not all Desktops have 4
>voltages coming out of their power supplies, plus and minus 5v and plus
>and minus 12v. For the most part the 12v are for drives, fans, etc. and
>the 5v are for the IC's or whatever. Does everything inside a laptop,
>drives and IC's run off of the one voltage, whatever it is, supplied by
>the battery?

Laptops have power converters inside them that take the wall or
battery voltage (which can very a bit) and make the individual
voltages to run whatever parts are inside. 5V, 12V, 1-2V for the CPU
core, negative voltages for the RS-232 ports, whatever is needed.
Anonymous
a b D Laptop
November 17, 2004 11:15:13 AM

Archived from groups: comp.sys.laptops (More info?)

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:419AAEC1.6030907@neo.rr.com...
> It's DC.

Figured that! :) 

>
>
> Jack Gillis wrote:
>
>> What is the output form of a typical laptop charger? Is it full wave
>> or half wave rectification. Is it filtered or smoothed in any way?
>>
>> No big deal. Just wondering.
>>
>> Thank you.
Anonymous
a b D Laptop
November 17, 2004 11:50:14 AM

Archived from groups: comp.sys.laptops (More info?)

Thanks again William. That makes sense.

<William P.N. Smith> wrote in message
news:foimp0lfi0bh0nr00nq4pr1jc3lagk7okl@4ax.com...
> "Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>>That leads to another question. Most, if not all Desktops have 4
>>voltages coming out of their power supplies, plus and minus 5v and
>>plus
>>and minus 12v. For the most part the 12v are for drives, fans, etc.
>>and
>>the 5v are for the IC's or whatever. Does everything inside a laptop,
>>drives and IC's run off of the one voltage, whatever it is, supplied
>>by
>>the battery?
>
> Laptops have power converters inside them that take the wall or
> battery voltage (which can very a bit) and make the individual
> voltages to run whatever parts are inside. 5V, 12V, 1-2V for the CPU
> core, negative voltages for the RS-232 ports, whatever is needed.
>
>
Anonymous
a b D Laptop
November 17, 2004 2:12:29 PM

Archived from groups: comp.sys.laptops (More info?)

"Jack Gillis" <XXXXXXXX@widomaker.com> wrote in message
news:10pking558gted0@corp.supernews.com...
> What is the output form of a typical laptop charger? Is it full wave or
> half wave rectification. Is it filtered or smoothed in any way?
>
> No big deal. Just wondering.
>
> Thank you.
>

the charger is a switch mode unit. The output is technically derived from a
half wave rectifier, but the way the oscillator driving the rectifier works
coupled with the filtering, means that efficiencies of around 90% or higher
with waveforms equating to steady DC are supplied albeit with a very small
amount of high frequncy ripple.

Ian.
Anonymous
a b D Laptop
November 17, 2004 2:12:30 PM

Archived from groups: comp.sys.laptops (More info?)

"Electrik Fan Club" <ian.shorrocks@baeyourclothessystems.com> wrote in
message news:419b3045_1@baen1673807.greenlnk.net...
>
> "Jack Gillis" <XXXXXXXX@widomaker.com> wrote in message
> news:10pking558gted0@corp.supernews.com...
>> What is the output form of a typical laptop charger? Is it full wave
>> or
>> half wave rectification. Is it filtered or smoothed in any way?
>>
>> No big deal. Just wondering.
>>
>> Thank you.
>>
>
> the charger is a switch mode unit. The output is technically derived
> from a
> half wave rectifier, but the way the oscillator driving the rectifier
> works
> coupled with the filtering, means that efficiencies of around 90% or
> higher
> with waveforms equating to steady DC are supplied albeit with a very
> small
> amount of high frequncy ripple.
>
> Ian.
>
>
>

Thank you. I've run into RFI problems with that high frequency ripple
on a switching power supply for an Icom Amateur transceiver years ago.
A couple of torroids on the leads fixed it but it drove me nuts until I
figured out what was causing the problem.
Anonymous
a b D Laptop
November 17, 2004 6:51:01 PM

Archived from groups: comp.sys.laptops (More info?)

No, everything does not run off of one voltage.

The charger is a DC switching power supply for the laptop (in most cases
it is single voltage, but in a few cases part of the charging circuit is
in the charger and it supplies multiple voltages, and possibly even some
of the charging control logic).

Meanwhile, the laptop has within it yet another switching power supply
that supplies the multiple voltages needed internally by the laptop.
The charger's output is the input to this supply.


Jack Gillis wrote:
> <William P.N. Smith> wrote in message
> news:k6blp0tr1uk2oe9h67qjfbjhq4scofrto4@4ax.com...
>
>>"Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>>
>>>What is the output form of a typical laptop charger? Is it full wave
>>>or
>>>half wave rectification. Is it filtered or smoothed in any way?
>>
>>They are all regulated DC voltages, from switching power supplies.
>>
>
>
> Thank you, William.
>
> OK. That makes sense to me. Especially with Mike's follow on comment.
>
> That leads to another question. Most, if not all Desktops have 4
> voltages coming out of their power supplies, plus and minus 5v and plus
> and minus 12v. For the most part the 12v are for drives, fans, etc. and
> the 5v are for the IC's or whatever. Does everything inside a laptop,
> drives and IC's run off of the one voltage, whatever it is, supplied by
> the battery?
>
> Thanks again.
>
>
Anonymous
a b D Laptop
November 17, 2004 6:51:02 PM

Archived from groups: comp.sys.laptops (More info?)

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:419B7416.1060805@neo.rr.com...
> No, everything does not run off of one voltage.
>
> The charger is a DC switching power supply for the laptop (in most
> cases it is single voltage, but in a few cases part of the charging
> circuit is in the charger and it supplies multiple voltages, and
> possibly even some of the charging control logic).
>
> Meanwhile, the laptop has within it yet another switching power supply
> that supplies the multiple voltages needed internally by the laptop.
> The charger's output is the input to this supply.

That makes perfect sense and I thank you.

>
>
> Jack Gillis wrote:
>> <William P.N. Smith> wrote in message
>> news:k6blp0tr1uk2oe9h67qjfbjhq4scofrto4@4ax.com...
>>
>>>"Jack Gillis" <XXXXXXXX@widomaker.com> wrote:
>>>
>>>>What is the output form of a typical laptop charger? Is it full
>>>>wave or
>>>>half wave rectification. Is it filtered or smoothed in any way?
>>>
>>>They are all regulated DC voltages, from switching power supplies.
>>>
>>
>>
>> Thank you, William.
>>
>> OK. That makes sense to me. Especially with Mike's follow on
>> comment.
>>
>> That leads to another question. Most, if not all Desktops have 4
>> voltages coming out of their power supplies, plus and minus 5v and
>> plus and minus 12v. For the most part the 12v are for drives, fans,
>> etc. and the 5v are for the IC's or whatever. Does everything inside
>> a laptop, drives and IC's run off of the one voltage, whatever it is,
>> supplied by the battery?
>>
>> Thanks again.
!