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'[EE] non-auto Lithium battery charging'
2006\01\12@175752 by Pedro Drummond

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face

Hi, friends

Lost my cell phone charger.

How can I quickly and painless charge its battery, with a good DC supply?
Any good hints and major do's or don'ts ?

TIA,

Pedro Drummond






-----Mensagem original-----
De: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] Em nome de Dave
Dilatush
Enviada em: domingo, 8 de janeiro de 2006 13:32
Para: Microcontroller discussion list - Public.
Assunto: Re: [EE] adding more tags...

Shawn Wilton wrote...

>...And it would really be a good idea to expose the pic crowd to AVR
>discussion, and vice versa.

You're missing something really, REALLY basic, here: the reason the tags are
there in the first place, is so we can **MAKE OUR OWN DECISIONS** about what
we do and don't want to see.  Believe it or not, this "pic crowd" is not
some bunch of little children who need a nanny deciding for them what they
should be "exposed"
to.

If and when I decide I want to read AVR-related stuff, I can turn on the
[AVR] tag all by myself, thank you.  I don't need someone like you deciding
that it would be a "good idea" for me to read it.

2006\01\12@183749 by Robert Rolf

picon face


Pedro Drummond wrote:

>  
> Hi, friends
>
> Lost my cell phone charger.
>
> How can I quickly and painless charge its battery, with a good DC supply?
> Any good hints and major do's or don'ts ?


Very very carefully.

Most phones control the charge process themselves. The wall wart just
provides an approximately correct voltage so you just need
to supply something close.

Other phones, like Samsungs, put the smarts into the charger,
which is why their car charger cord is $100.
If your phone is the latter, and uses Lithium Ion batteries,
DO NOT EVEN THINK of charging it with DC supply.

If you're using NiCad of NiMHi then limit your charge current
to 200mA or so, and terminal voltage to about 1.34V per cell.

Use the above information AT YOUR OWN RISK!

Robert

2006\01\12@184425 by andrew kelley

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Got a nearby walmart? I *think* (dont hold me to it now,) that *most*
cell chargers are just supplies, no charge controllers.. I think that
the cell phone has the charge controller in it..  Give the cell phone
the right voltage and on the right pins and it should charge..
--andrew

On 1/12/06, Pedro Drummond <electronicsspamKILLspamglobo.com> wrote:
>
> Hi, friends
>
> Lost my cell phone charger.
>
> How can I quickly and painless charge its battery, with a good DC supply?
> Any good hints and major do's or don'ts ?

2006\01\12@211314 by Pedro Drummond

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face

No charger at all, I mean charging the battery *directly*. I have done it
many times already, using 0.2V to 0.3V above its nominal 3.7V, for only a
few minutes. Current goes from 800mA to 400mA during these 2 to 4 minutes.
It charges the battery to an operational level (good for one or two more
days) and the battery doesn't even get warm. It remains really cold during
the whole charging process.

When I have my charger with me, I sometimes charge the battery for only a
few minutes and the phone works for 1 or 2 days after that. I assume my
charger does something very similar to this manual process in its first
minutes of charging.

If attended during the whole time and carefully done, this process helps in
an emergency. But, although it works, I understand it requires attention and
is far from ideal. That is why I addressed it to the list.

Still doing it manually, is there a way to improve it?

2006\01\13@034901 by Michael Rigby-Jones

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{Quote hidden}

Yes, you could build a charger using one of the many Li-Ion charger IC's available (even Microchip has a good selection).  The most important aspect of charging these batteries is the terminal voltage which should never be allowed to exceed the limit specified by the manufacturer, usualy around 4.1-4.2 volts.  The charger also must be current limited, 800mA is likely too much for a small Li-Ion (or Li-Poly) cell.  1/10C is generaly a safe charging rate (i.e. a 1/10th of the capacity). You must never leave the battery "trickle" charging; once the terminal voltage has been reached charging MUST be stopped. There are numerous other conditions that need to be catered for in a commercial design, take a look at http://www.batteryuniversity.com/partone-12.htm

Regards

Mike

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2006\01\13@065506 by olin piclist

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Pedro Drummond wrote:
> How can I quickly and painless charge its battery, with a good DC
> supply?

Go to store, buy cell phone charger, plug it in.  Anything else would not be
quick and possibly not painless.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\01\13@084519 by Ling SM

picon face
>>Still doing it manually, is there a way to improve it?

My consumer report, not technical one that you may be looking for, for
emergency I got these:

<page.auctions.yahoo.com/sg/auction/95991923>
<page.auctions.yahoo.com/sg/auction/95991904>
<page.auctions.yahoo.com/sg/auction/95991918>
<page.auctions.yahoo.com/sg/auction/95991921>
<http://page.auctions.yahoo.com/sg/auction/95991063>

There must be better offerings over ebay.

To reduce stress level and improve peace of mind, get an adapter to
backup the phone numbers.

Cheers, Ling SM

2006\01\13@151607 by M. Adam Davis

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On 1/12/06, Pedro Drummond <electronicsspamspam_OUTglobo.com> wrote:
>
> Hi, friends
>
> Lost my cell phone charger.
>
> How can I quickly and painless charge its battery, with a good DC supply?
> Any good hints and major do's or don'ts ?

First two links of this google search:
http://www.google.com/search?q=lithium+ion+charging+process

www.batteryuniversity.com/partone-12.htm
http://www.web-ee.com/primers/files/li-ioncharge.pdf

Essentially apply a charging current to the cell until the cell
reaches max voltage, then apply charging voltage to cell until cell
draws little current.

If you don't know you particular cell's properties or current charge
state, you can generally apply 100mA until it reaches 4V, then apply
4V until it draws less than 100mA to top off.  A quick circuit for
this is a 4V regulator followed by a 0.1mA current limiter with
careful watching of the current so you turn it off at the appropiate
time.

You may be able to apply a higher charging current, and you may be
able to top off with 4.1 or even 4.2V, but without more information
it's impossible to tell.

For a quick get-me-through-this-week charge, just apply 100mA for 5
hours whenever it drops to below 50%.  You won't get a full charge,
but it's unlikely that you'll destroy the battery either.

Good luck.  Don't blame me if your battery or phone explode,
destroying your residence or head - this is for experimental lab use
only, etc, etc, etc.

-Adam

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