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Li-ion charger

M

martin griffith

Jan 1, 1970
0
Recently I heard RS had waived the requirement to be an account holder, so I
emailed them and they sent me the CD cat. As I wanted some LEDs I logged on
to view the data sheets before deciding which ones to buy and their system
refused me access! They ignored my email asking about this so I didn't
bother with them anymore!!!
Got the same prob here in spain, with spanish RS, I'll have to create
yet another yahoo acount, cos RS's IT dept is crap, and wont let me
have the same account name/email address in two countries


martin
 
I

ian field

Jan 1, 1970
0
Tim Auton said:
By 'refused me access' do you mean it wouldn't let you have the
datasheets without logging in? That always was annoying, but I noticed
recently that you don't need to be logged in to see datashets any more.
Even before that, creating the required account was pretty
straightforward, even if it was a pointless inconvenience.


Tim

After logging in I sat watching a slow moving progress bar, after about 5
mins it opened a blank white html page!!!
 
ian said:
Before I blow myself up - what is the simplest safe charger design for
Li-ion cells?!!!

TIA.

I haven't opened a battery pack in a while, so I don't know about
current technology. However, if you want to play it safe, you
incorporate a cell protector chip in the pack:
<http://focus.ti.com/lit/ds/symlink/bq29405.pdf#search="lion cell protector chip">
as one of a few examples. Such chips used to be a requirement.

Initially, Sony wouldn't sell Lion cells without their protection
chips. Eventually "bare" cells hit the market so I gather they dropped
that requirement.
 
I

ian field

Jan 1, 1970
0
I haven't opened a battery pack in a while, so I don't know about
current technology. However, if you want to play it safe, you
incorporate a cell protector chip in the pack:
<http://focus.ti.com/lit/ds/symlink/bq29405.pdf#search="lion cell protector chip">
as one of a few examples. Such chips used to be a requirement.

Initially, Sony wouldn't sell Lion cells without their protection
chips. Eventually "bare" cells hit the market so I gather they dropped
that requirement.

Thanks - lots of info coming in, including what I googled. From some of what
I've read I'm beginning to think I need a long strip of flexiprint - so I
can hang the battery being charged out the window!!!
 
M

Michael A. Terrell

Jan 1, 1970
0
ian said:
The Sony connection is something I should have guessed! From my monitor
repair days quite a lot of Dell monitors were Sony's in disguise. Quality
was either very good or very bad _ one model in particular had a tall steel
heatsink in the middle of the board which hit the CRT bowl if the base
flexed, Sony decided that the best cure was to glue a rubber block to the
CRT, this trapped the heatsink between the PCB and block so the PCB warped
and cracked!!!


I'm not sure that Sony makes anything worth buying, anymore. Have you
looked at their PCs? Every one I get my hands on is already half
stripped.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
ian said:
Thanks - lots of info coming in, including what I googled. From some of what
I've read I'm beginning to think I need a long strip of flexiprint - so I
can hang the battery being charged out the window!!!

My recollection is the average notebook computer battery could be made
to explode like a stick and a half of dynamite. Many notebooks hide
bits of the battery charger control software in the keyboard controller
to kept it away from the hackers. Technically, every chipset has SMB
control, but I don't know how many use the port to control the pack
since it could be hacked.

Note that in this Dell fiasco, I blame the charger electronics. You
will get crap cells from time to time and the charger should not charge
crap. Period, end of story, no excuses, failure is not an option. Fool
proof electronics is not simple.
 
Baloney. The Sony cells blew up due to metal particles causing internal
shorts. It actually had nothing to do with charging. Furthermore, there
is no electrical means to detect this before it's too late. Even
sensing battery temperature (which is done already) gives the warning
too late. I'm afraid this is a case where the battery simply has to be
made properly to avoid this. You can't blame it on the charger. Due the
amount of money involved I'm sure Sony would have *loved* to blame it
on the charger.

Now one thing the OP might want to know is that if you don't need to
squeeze every ounce of run-time from the battery, you will get much
bettery life (number of charge cycles) by charging to 4.1V (or lower)
rather than 4.2V. Some, but no all charger chips allow this, so it
would not be entirely crazy to roll your own charger. It really is only
a current limited voltage source. If you want to be really nice to the
cells you can add a charge timer and circuit to cut charge current to
1/10 when the battery is less then 3V. That's really all there is.

The downside of lower charge voltage is of course less run time, so you
have to decide about the tradeoff.
 
P

Philip Pemberton

Jan 1, 1970
0
Michael said:
I'm not sure that Sony makes anything worth buying, anymore. Have you
looked at their PCs? Every one I get my hands on is already half
stripped.

Most of the problems I've had with Sony kit were with their low-end products.
Stuff from the mid- to high-end seems to be pretty well built IME.
 
P

PeteS

Jan 1, 1970
0
I haven't opened a battery pack in a while, so I don't know about
current technology. However, if you want to play it safe, you
incorporate a cell protector chip in the pack:
<http://focus.ti.com/lit/ds/symlink/bq29405.pdf#search="lion cell protector chip">
as one of a few examples. Such chips used to be a requirement.

Initially, Sony wouldn't sell Lion cells without their protection
chips. Eventually "bare" cells hit the market so I gather they dropped
that requirement.

A small operation can't buy 'bare' Li+ cells in the UK (nor all the EU,
I believe). You have to show what protection you are applying and it
has to be certified, which only makes sense for OEMs with the time and
money (and expected shipments) to do such an exercise.
If you are buying cell packs from a retailer (such as RS or Farnell)
then they should have the protectors already in the pack. The
protectors protect at a minimum against overvoltage events.

Cheers

PeteS
 
I

ian field

Jan 1, 1970
0
Baloney. The Sony cells blew up due to metal particles causing internal
shorts. It actually had nothing to do with charging. Furthermore, there
is no electrical means to detect this before it's too late. Even
sensing battery temperature (which is done already) gives the warning
too late. I'm afraid this is a case where the battery simply has to be
made properly to avoid this. You can't blame it on the charger. Due the
amount of money involved I'm sure Sony would have *loved* to blame it
on the charger.

Now one thing the OP might want to know is that if you don't need to
squeeze every ounce of run-time from the battery, you will get much
bettery life (number of charge cycles) by charging to 4.1V (or lower)
rather than 4.2V. Some, but no all charger chips allow this, so it
would not be entirely crazy to roll your own charger. It really is only
a current limited voltage source. If you want to be really nice to the
cells you can add a charge timer and circuit to cut charge current to
1/10 when the battery is less then 3V. That's really all there is.

The downside of lower charge voltage is of course less run time, so you
have to decide about the tradeoff.

Thanks that's handy to know, although what I've read so far very small drops
in charging voltage result in relatively large drops in charge capacity -
but OTOH a lithium fire indoors is not an option!!!
 
M

Michael A. Terrell

Jan 1, 1970
0
Philip said:
Most of the problems I've had with Sony kit were with their low-end products.
Stuff from the mid- to high-end seems to be pretty well built IME.


It must be so high end that none of the stores around here sell it.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
I

ian field

Jan 1, 1970
0
My recollection is the average notebook computer battery could be made
to explode like a stick and a half of dynamite. Many notebooks hide
bits of the battery charger control software in the keyboard controller
to kept it away from the hackers. Technically, every chipset has SMB
control, but I don't know how many use the port to control the pack
since it could be hacked.

Note that in this Dell fiasco, I blame the charger electronics. You
will get crap cells from time to time and the charger should not charge
crap. Period, end of story, no excuses, failure is not an option. Fool
proof electronics is not simple.

Since the Dell incidents the battery bin at the local tip has been the new
home of an increasing number of Li laptop packs, all that I've opened so far
had some circuitry but so far I've not been able to identify any chips to
download the data sheets. If I persevere this situation may change.
 
Baloney. The Sony cells blew up due to metal particles causing internal
shorts.

Oh, and the shorts couldn't be detected? Hardly.

Oh, if only there was a law relating voltage, current and resistance.
;-)

It actually had nothing to do with charging. Furthermore, there
 
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