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'[PIC]: PIC based NiMH charger'
2005\12\23@210607 by Philip Pemberton

face picon face
Hi,
 After having yet another NiMH charger die on me (at least this one gave me
a firework display before it gave up), I started thinking... what about
building a battery charger... The question turned to "What should I use to
control it" - the answer inevitably ended up being "a PIC".

 Has anyone built an "intelligent" NiMH charger out of a PIC? What I'm
thinking about building is something with these specs:

 - Reflex (aka burp, negative pulse, ...) and Constant Current Fast charging
 - Charge current variable from 50mA to 2A
 - Discharge pulse current variable from 100mA to 5A
 - Timing variable from 30 minutes to 8 hours
 - Onboard voltage-vs-time data log (I need an excuse to use one of those
   FRAM chips that's been cluttering my junkbox for ages)
 - Charges 1 to 4 NiMH cells
 - PC link to download data log, view charger status, upgrade firmware and
   tweak algorithm timing
 - 16x2 LCD display

 As far as current regulation goes, I was going to use an opamp with a
push-pull driver stage to do both charging and discharging. A DAC will be
used to produce a +/- 2.048V signal that'll be fed to the opamp to select the
charge/discharge voltage.

 What I'm thinking about is something along the lines of an ICS1702, but
implemented in a far more versatile way... That said, it seems Galaxy Power
have vanished, so ICS1702s might be a little hard to get anyway...

 Anyone got any comments on this? Is it worth bothering implementing Reflex
charging, or should I just stick to constant-current with voltage-delta
termination?

 Yes, I know this could potentially turn into a REALLY expensive project,
but I've had two chargers die recently, and I'm sick of spending good money
on something I'm not even sure is charging the batteries properly... At least
if I build my own, I get to play with the algorithms and make DAMN SURE it's
charging them properly.

Thanks,
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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... Anything not nailed down is a cat's toy

2005\12\23@220851 by rosoftwarecontrol

flavicon
face
In market, there are really no
good charger than what you describe
below.

But it seems too expensive if reach
the specification of yours. discharge
5A? Charge 5A is easier than
discharge 5A. So, simplifying you
plan seems unavoidable.

Through too long time trying and
step by step solving, I have one
pic charger running on my table.
realiable and playable. Those big
ic manufacture's charger ic, none
of them really work! most funny thing
is those 15min/one hour charger,
they are just battery killers or 1/3-charger.
For example one simply problem they missed:
contact resistant of battery holder is all time changing!




{Original Message removed}

2005\12\24@073824 by Philip Pemberton

face picon face
In message <001c01c60829$f85725a0$9d42acce@personalrvuq8e>
         "microsoftwarecontrol" <.....microsoftwarecontrolKILLspamspam@spam@yahoo.ca> wrote:

> But it seems too expensive if reach
> the specification of yours. discharge
> 5A? Charge 5A is easier than
> discharge 5A. So, simplifying you
> plan seems unavoidable.

The 5A discharge pulse only has to be sustained for 5ms. I've got an MJE2955T
that should be able to handle that.
I might make the charge/discharge system symmetrical - i.e. 5A charge or 5A
discharge. The charge system would only ever run at a maximum of 2.5A though.

Reflex charging supposedly works by using a negative pulse to "knock" the
hydrogen bubbles off the cell plates - the "metal hydride" portion of the
cell then recombines these into the cell electrolyte. Because you're not
getting as many H2 bubbles sticking to the plates, you can push more power
into the cell. That's the theory, anyway.

As long as I can charge a 1600mAh Kodak AA NiMH in three hours, I'll be
happy.

Like I said, the whole point of the experiment is to make a charger that I
can use not only to charge my NiMHs, but also to play with charge algorithms.
It's also an excuse to play around with high current switchmode converters
and power transistors :)

> Those big
> ic manufacture's charger ic, none
> of them really work! most funny thing
> is those 15min/one hour charger,
> they are just battery killers or 1/3-charger.

The MAX712/713 isn't too bad, but it's not the best charger in the world
either. OTOH, at least its charge termination circuit is reliable, unlike
most of the Chinese elcheapo chargers I've used...

Later.
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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... Law of Insurance and Taxes - Whatever goes up, stays up.

2005\12\24@082507 by olin piclist

face picon face
Philip Pemberton wrote:
> Has anyone built an "intelligent" NiMH charger out of a PIC?

Yes.  I built one for some small 3-cell 400mAH NiMH packs.  It's been a
while, but I think it was controlled by a 18F252.  I used to have it on the
web site somewhere, but I'm not sure it's there anymore.

>  - Onboard voltage-vs-time data log (I need an excuse to use one of
>    those FRAM chips that's been cluttering my junkbox for ages)

I just had it send data out a serial port.  If I wanted log information I
would run it while connected to a PC.

>  - PC link to download data log, view charger status, upgrade firmware
>    and tweak algorithm timing

RS-232 is easy.  It may be easier to provide the ICSP connection and install
new firmware with a programmer than to mess with a bootloader.  You will
need the ICSP connection for debugging anyway unless you have a ICE.  Or you
could even socket the PIC and program it externally if you don't want to
give up the pins.  Even if you update the firmware 100 times, it's still
very unlikely that this will take more time than integrating and testing a
bootloader.

>  - 16x2 LCD display

Unless you really really need it to display what it's doing stand alone, it
could just send regular status out the serial port and a PC program displays
it for you.  I dealt with the status of each of the 5 ports of my charger
with a single LED per port.  You can do a lot with various flashing
patterns.

> As far as current regulation goes, I was going to use an opamp with a
> push-pull driver stage to do both charging and discharging. A DAC will
> be used to produce a +/- 2.048V signal that'll be fed to the opamp to
> select the charge/discharge voltage.

Charging should be current, not voltage, controlled.  I did mine with two
separate circuits.  The discharge was a resistor to ground via a NPN
transistor.  You don't need anything too fancy to discharge the cells.  The
charge circuit was a voltage controlled current source.  PWM signals from
the PIC were filtered to produce the control voltages.  This was all
software PWM, but nothing needs to be done very quickly so it could be
heavily filtered to allow good resolution.

> That said, it seems Galaxy Power have vanished,

They are now Bel Power, a division of Bel Fuse.


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

2005\12\24@085919 by Philip Pemberton

face picon face
In message <003601c6088d$70f4f330$0201a8c0@dad>
         .....olin_piclistKILLspamspam.....embedinc.com (Olin Lathrop) wrote:

> Yes.  I built one for some small 3-cell 400mAH NiMH packs.  It's been a
> while, but I think it was controlled by a 18F252.  I used to have it on the
> web site somewhere, but I'm not sure it's there anymore.

Unbelievable. I was going to use an 18F252 as well...

> I just had it send data out a serial port.  If I wanted log information I
> would run it while connected to a PC.

Actually, that's a better idea than my "save to FRAM" idea. Send an 8-byte
burst every second or so with the current voltage and charge state for all
the cells...

> RS-232 is easy.  It may be easier to provide the ICSP connection and install
> new firmware with a programmer than to mess with a bootloader.  You will
> need the ICSP connection for debugging anyway unless you have a ICE.

No ICE, just an ICD2.

> Unless you really really need it to display what it's doing stand alone, it
> could just send regular status out the serial port and a PC program displays
> it for you.  I dealt with the status of each of the 5 ports of my charger
> with a single LED per port.  You can do a lot with various flashing
> patterns.

The thing is, I've got a lot (and I mean *A LOT*) of different sizes and
shapes of 1.2V NiMH. Some are 750mAh, some are 1600... What I want is
something I can push a button on, select a charge profile (current,
termination method, ...) then hit "GO" and leave it to charge. When it's
done, I'd like to have a little "Charged to <n> volts, <x> milliamp-hours of
charge in cell <y>" type display. Completely frivolous, but fun.

> Charging should be current, not voltage, controlled.

It is. What I MEANT to say was:
 - There's a DAC that produces a 0V-4.096V voltage
 - That voltage is fed to all four charge controllers to set the current.
Discharge current is always twice the charge current.
 - Two I/O lines are used to select charge, discharge, rest or "blow the
output transistors to pieces" mode. The latter is seldom used.

I doubt I'll ever want to charge a pair of AAs at the same time as a pair of
AAAs, so "assume every cell in the charger has the same specs" is probably
the way to go. Makes the firmware easier to deal with, and reduces cost too.
Much as I'd love to have a DAC for each battery, DACs are expensive!

I was planning to have an interrupt handler do all the timing and acquisition
stuff. Every millisecond, a timer is decremented. If that timer reaches zero,
the charger enters the next state - either "charge pulse", "rest", "discharge
pulse", or "measurement N of 12". The main thread is responsible for making
sure the reload values for the timers are correct. Software PWM, four ways,
with different timing relationships (one cell may have a delta-peak and enter
Top-off Charge mode before the other three do).

Once the main code has seen a voltage-peak, the charger switches from fast
charge to top-off mode, and the display is updated to reflect that. Once
top-off charging has finished, the display is changed to "Charge Complete:
Maintenance Mode" and the cell gets a C/10 charge to keep it topped up until
it's eventually removed from the charger. Once the cells are removed, charge
current is cut off, the timer interrupt is turned off and the program waits
for something to happen (i.e. more batteries are inserted, and the START
button gets pushed). The cycle then repeats (well, until the charger gets
unplugged that is).

This is all in flux at the moment - I know I'm going to use a transistor
current source/sink, but I'm not sure how I'm going to set up the opamps to
drive it.

> > That said, it seems Galaxy Power have vanished,
>
> They are now Bel Power, a division of Bel Fuse.

Are you sure we're talking about the same company? The Galaxy Power I'm
talking about made battery charger ICs and were based in Valley Forge, PA
(going by the Google map, not far from the old MOS Technology / Commodore /
GMT Microelectronics fab plant). Their old website was http://www.galaxypower.com,
but that's been down for ages (and has since been bought up by one of those
"ultimate search" companies).

The one you appear to be talking about appear to have made power supplies...

Thanks.
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
EraseMEphilpemspam_OUTspamTakeThisOuTphilpem.me.uk              | Athlon64 3200+ A8VDeluxe R2 512MB+100GB
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Think "honk" if you're a telepath.

2005\12\24@090507 by David VanHorn

picon face
> > As far as current regulation goes, I was going to use an opamp with a
> > push-pull driver stage to do both charging and discharging. A DAC will
> > be used to produce a +/- 2.048V signal that'll be fed to the opamp to
> > select the charge/discharge voltage.
>
> Charging should be current, not voltage, controlled.  I did mine with two
> separate circuits.  The discharge was a resistor to ground via a NPN
> transistor.  You don't need anything too fancy to discharge the
> cells.  The
> charge circuit was a voltage controlled current source.  PWM signals from
> the PIC were filtered to produce the control voltages.  This was all
> software PWM, but nothing needs to be done very quickly so it could be
> heavily filtered to allow good resolution.


I've done this as well, using an AVR to PWM a buck regulator at 500 kHz for
constant current, but I did get some indication from an electrochemist that
does battery chargers for a living, that NIMH can be charged by a regulated
source at 1.5V/Cell, more in a manner like you would a Gel-Cell.

NIMH is pretty interesting to charge, if you try to implement all the rules
that you'll find in the good data sheets from Panasonic and Sanyo.

2005\12\24@090704 by David VanHorn

picon face
>
>
> > > That said, it seems Galaxy Power have vanished,
> >
> > They are now Bel Power, a division of Bel Fuse.
>
> Are you sure we're talking about the same company? The Galaxy Power I'm
> talking about made battery charger ICs and were based in Valley Forge, PA
> (going by the Google map, not far from the old MOS Technology / Commodore
> /
> GMT Microelectronics fab plant). Their old website was http://www.galaxypower.com
> ,
> but that's been down for ages (and has since been bought up by one of
> those
> "ultimate search" companies).


Well, I'm glad I saved all those data sheets then!

2005\12\24@091204 by olin piclist

face picon face
Philip Pemberton wrote:
>> They are now Bel Power, a division of Bel Fuse.
>
> Are you sure we're talking about the same company? The Galaxy Power I'm
> talking about made battery charger ICs and were based in Valley Forge,
> PA (going by the Google map, not far from the old MOS Technology /
> Commodore / GMT Microelectronics fab plant). Their old website was
> http://www.galaxypower.com, but that's been down for ages (and has since been
> bought up by one of those "ultimate search" companies).
>
> The one you appear to be talking about appear to have made power
> supplies...

Yes, the one I'm talking about made power supplied.  They had a plant in
Westboro Massachusetts, which I think was also their headquarters but I'm
not sure about that.  I didn't realize there was more than one Galaxy Power.


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

2005\12\24@092959 by David VanHorn

picon face
>
>
>
> Yes, the one I'm talking about made power supplied.  They had a plant in
> Westboro Massachusetts, which I think was also their headquarters but I'm
> not sure about that.  I didn't realize there was more than one Galaxy
> Power.



These guys?
http://www.galaxypwr.com/

Looks like the one that did charger chips went "poof"..

2005\12\24@095858 by Gerhard Fiedler

picon face
Philip Pemberton wrote:

> I doubt I'll ever want to charge a pair of AAs at the same time as a pair of
> AAAs, so "assume every cell in the charger has the same specs" is probably
> the way to go. Makes the firmware easier to deal with, and reduces cost too.
> Much as I'd love to have a DAC for each battery, DACs are expensive!

One DAC and four S/H (could be done with four analog switches) would do it,
too. Is not exactly expensive.

Gerhard

2005\12\24@104931 by Philip Pemberton

face picon face
In message <1fd6wbzavwwj8$.p29azdzrtm34.dlgspamspam_OUT40tude.net>
         Gerhard Fiedler <@spam@listsKILLspamspamconnectionbrazil.com> wrote:

> One DAC and four S/H (could be done with four analog switches) would do it,
> too. Is not exactly expensive.

Hmm, 4066es are like 50p in qty 1, and I might have one I can scavenge... A
1uF should be able to store enough charge to drive an opamp for a second or
so... hmm...

Looks like I've found my solution. That still leaves the firmware to deal
with, though.

Thanks,
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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2005\12\24@113836 by olin piclist

face picon face
David VanHorn wrote:
> These guys?  http://www.galaxypwr.com/

Yup those are the power supply folks I was thinking of, which is apparently
a different company from the one Phil was looking for.


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

2005\12\24@115050 by David VanHorn

picon face
>
> Yup those are the power supply folks I was thinking of, which is
> apparently
> a different company from the one Phil was looking for.


There was a company by the same name, who made some rather capable charger
chips.
They seem to be defunct though.  Pity, their data sheets were most
informative.

2005\12\25@063622 by Howard Winter

face
flavicon
picon face
Phil,

On Sat, 24 Dec 2005 13:59:06 GMT, Philip Pemberton wrote:

>...
> Once top-off charging has finished, the display is changed to "Charge Complete:
> Maintenance Mode" and the cell gets a C/10 charge to keep it topped up until
> it's eventually removed from the charger.

I may be wrong, but I'd have thought C/10 was too much for a maintenance charge - if you forget they're in
there for a day or two (I do that sort of thing!) you would have given them an overcharge of 2C or more, which
seems a bit OTT.

Oh, and Merry Christmas!

Cheers,


Howard Winter
St.Albans, England


2005\12\25@065038 by Philip Pemberton
face picon face
In message <RemoveME200512251136.jBPBaMFh004282TakeThisOuTspamfort-point-station.mit.edu>>          "Howard Winter" <spamBeGoneHDRWspamBeGonespamH2Org.demon.co.uk> wrote:

> I may be wrong, but I'd have thought C/10 was too much for a maintenance
> charge - if you forget they're in
> there for a day or two (I do that sort of thing!) you would have given them
> an overcharge of 2C or more, which
> seems a bit OTT.

It seems high because it's a number I plucked out of thin air!
Actual "maintenance" rate is more likely to be C/20, C/50 or C/100. Depends
what I decide when I've read all the datasheets.

I don't tend to leave batteries in the charger for more than an hour or so
after they've finished charging anyway.

> Oh, and Merry Christmas!

Merry {Christmas,Newtonsday,non-denominational winter holiday} to you too :)

Thanks,
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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2005\12\25@105115 by David VanHorn

picon face
>
>
> It seems high because it's a number I plucked out of thin air!
> Actual "maintenance" rate is more likely to be C/20, C/50 or C/100.
> Depends
> what I decide when I've read all the datasheets.



Some NIMH cells spec ZERO overcharge, and some can handle up to C/10
although they don't really like it.

2005\12\25@170429 by Philip Pemberton

face picon face
In message <RemoveME25b178740512250751u5c4e6eb8o207d50c2729231b7spamTakeThisOuTmail.gmail.com>>          David VanHorn <dvanhornEraseMEspam.....microbrix.com> wrote:

> Some NIMH cells spec ZERO overcharge, and some can handle up to C/10
> although they don't really like it.

*scribbles out "maintenance charge" section of his design plan*

Right, that's one less thing to write code for :)

Thanks.
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
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... I'm an absolute, off-the-wall fanatical moderate.

2005\12\25@172532 by David VanHorn

picon face
>
>
> *scribbles out "maintenance charge" section of his design plan*
>
> Right, that's one less thing to write code for :)



not a bad idea really, if you can't predict what sort of cells you'll be
working with.

In my implementation, I went through a number of phases.

First, sanity check on all voltages, temperatures, reference voltage.
Second, measure the battery, and apply a low charge if the temperature is
low, or state of charge is extremely low
Then high rate charge
Then topping charge
Then maintainance charge (My batteries can take it, and they are connected
direct to a load at all times)

Existing each phase resulted in an error code, and the error code controls
where you go next.
During each phase I periodically look to see if I'm hitting any panic
limits, like input voltage too high or low, battery temperature too high or
low, battery voltage too high or too low.. A panic exit forces a "reboot"
and re-evaluation of the situation.

2005\12\26@002558 by William Chops Westfield

face picon face
On Dec 25, 2005, at 2:06 PM, Philip Pemberton wrote:

>> Some NIMH cells spec ZERO overcharge, and some can handle up to C/10
>> although they don't really like it.
>
> *scribbles out "maintenance charge" section of his design plan*
>
> Right, that's one less thing to write code for :)
>
Most NiMH batteries go dead through self-discharge alarmingly quickly
(though there are supposed to be some new cells out there that improve
this a great deal.)  If you're like me, you really want some sort of
charger where you can go to get cells that are near full charge, and
just leave cells in there waiting for your arrival.  If they can't
take a maintenance charge, this makes the code MORE complicated rather
than less complicated!

BillW

2005\12\26@043127 by Shawn Wilton

picon face
You could always set a timer to disengage and reengage the timer after some
set period of time.  So if they sit for a week or so, then you can set a
trickle charge to bring them back up...

On 12/25/05, William Chops Westfield <RemoveMEwestfwEraseMEspamEraseMEmac.com> wrote:
{Quote hidden}

> -

2005\12\26@092755 by David VanHorn

picon face
>
>
> Most NiMH batteries go dead through self-discharge alarmingly quickly
> (though there are supposed to be some new cells out there that improve
> this a great deal.)


What do you call "alarmingly quickly"?  A few percent/month isn't all that
noticable if you're using the device routinely.

2005\12\26@104622 by Maarten Hofman

face picon face
> What do you call "alarmingly quickly"?  A few percent/month isn't all that
> noticable if you're using the device routinely.

In my experience with NiMH they discharge at about 30%/month. However,
this is different for each type of cell, it is best to consult the
manufacturer's battery manual, which should contain all the necessary
details. During the battery course given by Microchip they said almost
every battery can be charged at their discharge rate, which means you
should be able to charge most batteries in slightly over an hour, if
you monitor/control current and/or voltage correctly.

Greetings,
Maarten Hofman.

2005\12\26@111447 by David VanHorn

picon face
>
>
> In my experience with NiMH they discharge at about 30%/month. However,
> this is different for each type of cell, it is best to consult the
> manufacturer's battery manual, which should contain all the necessary
> details. During the battery course given by Microchip they said almost
> every battery can be charged at their discharge rate, which means you
> should be able to charge most batteries in slightly over an hour, if
> you monitor/control current and/or voltage correctly.


1C charge is the "sweet spot" for NIMH cells.  You can go to 2C or 0.5C if
you're careful, but the end of charge signals get indistinct.

One thing that I noticed was that the good quality cells have a very sharp
thermal excursion at end of charge, where the cheap cells (presumably
lacking the recombination catalyst) showed a more or less linear increase in
temperature.. These linear cells also had a habit of occasionally going into
spontaneous thermal runaway without provocation.

2005\12\26@163634 by Russell McMahon

face
flavicon
face
> 1C charge is the "sweet spot" for NIMH cells.  You can go to 2C or
> 0.5C if
> you're careful, but the end of charge signals get indistinct.
>
> One thing that I noticed was that the good quality cells have a very
> sharp
> thermal excursion at end of charge,

The "latest" idea is to install pressure sensors in the cells and use
a sudden pressure rise to signal end of charge. This is said to occur
very distinctly just prior to "thermal excursion" and is said to
stress cells far less and to safely allow much faster charging. YMMV.


       RM

2005\12\26@171550 by David VanHorn

picon face
The "latest" idea is to install pressure sensors in the cells and use
a sudden pressure rise to signal end of charge. This is said to occur
very distinctly just prior to "thermal excursion" and is said to
stress cells far less and to safely allow much faster charging. YMMV.

Yes, but AFAIK you can only charge one cell per charge system that way.
Not good for a six cell pack.

2005\12\26@200549 by olin piclist

face picon face
William Chops Westfield wrote:
> Most NiMH batteries go dead through self-discharge alarmingly quickly
> (though there are supposed to be some new cells out there that improve
> this a great deal.)  If you're like me, you really want some sort of
> charger where you can go to get cells that are near full charge, and
> just leave cells in there waiting for your arrival.  If they can't
> take a maintenance charge, this makes the code MORE complicated rather
> than less complicated!

In my NiMH charger I had it discharge and then recharge each cell every 2
weeks when nothing else was going on.  It was a 5 cell charger, so once all
cells were charged you were always guaranteed that 4 cells would be ready to
use.


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

2005\12\26@201203 by William Chops Westfield

face picon face
On Dec 26, 2005, at 6:27 AM, David VanHorn wrote:

>> Most NiMH batteries go dead through self-discharge alarmingly quickly
>> (though there are supposed to be some new cells out there that improve
>> this a great deal.)
>
> What do you call "alarmingly quickly"?  A few percent/month isn't all
> that
> noticable if you're using the device routinely.
>
The rather generic NiMH batteries I have were essentially useless after
a couple weeks sitting in a digital camera (turned off.  Your guess is
as good as mine as to how much current drain there was in the 'off'
state.)
That was unacceptable.  Perhaps they were especially crappy batteries,
self-discharge-wise.  Since that doesn't seem to something that shows
up in the reviews I read (which are all about raw capacity, usually),
I'm at a loss as to how to find better batteries that don't cost a
small fortune.  Do you have a particular brand of battery that achieves
that "few percent a month" number?  I guess I'm willing to pay some for
that ability, but I'd certainly rather not pay to search for batteries
having that ability!

The new Sanyo eneloop cells sound wonderful, and I trust Sanyo in the
rechargable battery market more than most, so I have high hopes...

(OTOH, I'd just as soon see Li-polymer made safer.  They already have
lovely storage properties...)

BillW

2005\12\26@234952 by Robert Ammerman

picon face

> The rather generic NiMH batteries I have were essentially useless after
> a couple weeks sitting in a digital camera (turned off.  Your guess is
> as good as mine as to how much current drain there was in the 'off'
> state.)

My otherwise very good digital camera (Fuji Finepix S602) has the nasty
habit of eating batteries for lunch, even when turned off. It will
completely kill a brand new set of 4 AA alkalines in a week or so.

Grrr!

Bob Ammerman
RAm Systems

2005\12\27@133626 by Peter

picon face

>brand

Most good make batteries do not self discharge significantly. I
understand that self discharge is a direct function of the purity of the
materials used. This is where the no-name makers skimp.

Peter

2005\12\27@135455 by David VanHorn

picon face
>
>
> Most good make batteries do not self discharge significantly. I
> understand that self discharge is a direct function of the purity of the
> materials used. This is where the no-name makers skimp.


Self discharge is significant on NIMH cells, but can be more so if cheaply
made.


Usually, nameplate capacity is what you will get.
The skimping happens in the vent structure, recombination catalyst, accuracy
of the electrolyte fill, and general purity of materials.

If you get the right combination of the first three elements, you end up
with a pressurized metal can full of rocket fuel and boiling potassium
hydroxide that will strip a PCB down a couple of layers when it vents.

But, at least the electrolyte isn't flammable! :)

2005\12\28@002830 by rosoftwarecontrol

flavicon
face
good make? after some time check my
batteries, I found double priced energier
has poor performance in high current,
which other ordinarilly price batteries
gives better and reliable performance.

I bough 4 2200mAh energizer, all of them
now is half dead comparing cheap 1800mAh one,
after less than 20 cycle. I remember in my
capcity test, they never reach 2200mAh and max
just over 2000. 2200mAh just is price, preducer's
desire or cheating word.

On commercial world, I persist the rule "simply is
the best" Uneccesary decoration and unreanoalbe improments,
only for fooling to buyer.

Don't follow TV ad to do buying and judging.


{Original Message removed}

2005\12\28@005516 by David VanHorn

picon face
>
>
> I bough 4 2200mAh energizer, all of them
> now is half dead comparing cheap 1800mAh one,
> after less than 20 cycle.



There is a significant possibility that what you bought did not come from
the factory that makes the real energizers.  Counterfieting is hitting the
battery market pretty hard.  Here in rural indiana, I can buy "Dunacell"
batteries, which perform rather badly when compared to the identical
appearing "Duracell" brand from reputable sources.  I know for a fact that
these "Dunacell" brand cells are only the tip of the iceberg. Some of the
counterfeit cells are made so that their external appearance is exactly the
same as the real thing.

2005\12\28@052042 by rosoftwarecontrol

flavicon
face
no, no, no. for example, did you ever heard
some one seriously telling expensive battery
really give him more time of using?
I found didn't. And serious capacity
test clearly showing tha  no much
difference in performance for energizer
and other cheap one.

now, I already mark my 2200mAh energizer as
1850mAh battery, is more than cheap one, but
only 90mAh more. cheap one I mark as 1760 mAh. Those are
their -dV condition, that I got from a very good
battery tester. If talking about uses for DC, 2200
mAh energizer will be rejected when has 1000mAh cap
left. The cheaper one, this figure is <300mAh, much better.

Think about how come you paid double price, for less performance
at high current?






{Original Message removed}

2005\12\28@101757 by David VanHorn

picon face
On 12/28/05, microsoftwarecontrol <RemoveMEmicrosoftwarecontrolspam_OUTspamKILLspamyahoo.ca> wrote:
>
> no, no, no. for example, did you ever heard
> some one seriously telling expensive battery
> really give him more time of using?


It's not just about the amp-hour capacity.  The "exploding" chinese cells
that I had gave identical capacity to the Sanyo cells which were twice the
price.  The thing is, none of the sanyo cells explode.

2005\12\28@111511 by rosoftwarecontrol

flavicon
face
wow. so you would pay double money for
sepcification "no exploding"? I just don't believe
between battery that they can charge and recharge,
existing the difference of "some will exploding".
How come? Making a battery to explode, is not
easy job if you know little battery chemistry.

I have been working on home eletronics industry,
talking quality of product, besides better decoration,
major stream Japan product have higher guarantee ratio,
that is well know fact. I prefer my price paid for performance
more than decoration or unwanted button. Unnecessary
button, unnecessary improvement, I believe is exactly what
happened for doubled price of energizer battery.




{Original Message removed}

2005\12\28@120242 by David VanHorn

picon face
On 12/28/05, microsoftwarecontrol <RemoveMEmicrosoftwarecontrolTakeThisOuTspamspamyahoo.ca> wrote:
>
> wow. so you would pay double money for
> sepcification "no exploding"?


Notice the word "exploding" in quotes.
The actual thing that happens, is that the battery goes into spontaneous
thermal runaway.
This is apparently caused by lack of appropriate catalyst material for
hydrogen and oxygen recombination, combined with a bad (or absent) vent
structure.

I don't see it as paying "double", so much as not paying half, and getting
garbage.
The original spec was for Sanyo or Panasonic cells, but I got pressured into
approving these cheap chinese cells at half the cost.  Thing is, I did a lot
of testing, and couldn't find any reason NOT to approve them, other than
previous experience with other "low cost" chinese products. When you can
take about 8% off your materials cost, that's pretty significant.

One of these batteries went into thermal runaway in a major customer's
hands, in front of HIS major customer, while I was on the phone with them.

FWIW, transporting batteries that don't have proper vents by air is subject
to something like a $USD 250,000 fine on first offence.

We immediately notified all our customers NOT to ship the batteries back to
us, but rather to put them in metal buckets, and take them to a recycling
center, and we scrambled to build new batteries from reputable cells.

There had been other reports and instances of "hot battery" and damaged
batteries, but these were blamed on charger firmware problems, and I think
that this issue cost us a lot of time and money before we found the real
cause of the problem.

Two years later, we have NO instances of thermal runaway.

So is that worth twice the price?  Damned right!

2005\12\28@141537 by Bob Axtell

face picon face
David VanHorn wrote:

{Quote hidden}

Be VERY wary of very low-cost Li-Ion cells regardless of "origin".

Yes, this story, or ones like it, have been substantiated. The one that
comes to MY mind
is the FAA story of a long-haul freight company which noticed, before
takeoff, that a
package of cells were smoking. By the time that the package had been
unloaded from
the plane, an open fire had started which COULD NOT be put out, jumping
from one
cell to the next, right there on the tarmac.

Notice to engineers: don't let your buyer influence you to accept
undocumented cells. If
the cells have no history, your company CANNOT afford to use them (A few
lawsuits have
been flying around. Rest assured that being identified as the approving
engineer on the
witness stand will be the most terrifying experience of your life).

I think that Li-Ion cells might be outlawed in the future if the safety
cannot be assured.

--Bob

--
Note: To protect our network,
attachments must be sent to
RemoveMEattachKILLspamspamengineer.cotse.net .
1-520-777-7606 USA/Canada
http://beam.to/azengineer

2005\12\28@143409 by David VanHorn

picon face
>
>
> Be VERY wary of very low-cost Li-Ion cells regardless of "origin".


These weren't even Lithium based, they were NIMH.

It scares me what might have happened had they been LI based, as in some
cases, they forcibly ejected the positive terminals from the case, and of
course the LI electrolytes are flammable.

2005\12\28@192501 by Philip Pemberton

face picon face
In message <25b178740512280717r69384134r26a2c3c4fecebf6cSTOPspamspamspam_OUTmail.gmail.com>>          David VanHorn <spamBeGonedvanhornSTOPspamspamEraseMEmicrobrix.com> wrote:

> It's not just about the amp-hour capacity.  The "exploding" chinese cells
> that I had gave identical capacity to the Sanyo cells which were twice the
> price.  The thing is, none of the sanyo cells explode.

The Sanyos are also a hell of a lot harder to find, especially around here.

"I'd like some NiMH batteries please."
"OK, we've got some made by GP, some by Uniross, and a few just in from
<insert name of Chinese 'amazing exploding battery' maker here>"
"Got any Sanyos?"
"Nope, we got some a while back but we couldn't sell them. Why do you want
those things, anyway, the GPs are just as good..."

Later.
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
KILLspamphilpemspamBeGonespamdsl.pipex.com              | Athlon64 3200+ A8VDeluxe R2 512MB+100GB
http://www.philpem.me.uk/          | Panasonic CF-25 Mk.2 Toughbook
Radioactive cats have 18 half-lives

2005\12\28@203328 by William Chops Westfield

face picon face
> did you ever heard some one seriously telling expensive battery
> really give him more time of using?
>
I'm with "Microsoftwarecontrol."  I am merely a "consumer" when it
comes to batteries; I don't have access to 'real' datasheets for most
of the products, don't trust the marketing literature that passes for
datasheets, have neither the time nor the budget to do my own testing,
and have little faith that a "brand name" battery performs better than
a noname brand from someplace like "batteryspace.com."  Given the way
"US manufacturing" works, I don't even have any faith that the noname
and
name brands aren't manufactured at exactly the same factory, with
nothing
to justify the inflated price other than the fancy packaging and cute
animated advertising...

BillW

2005\12\28@205220 by William Chops Westfield

face picon face

On Dec 28, 2005, at 11:15 AM, Bob Axtell wrote:

> Notice to engineers: don't let your buyer influence you to accept
> undocumented cells. If the cells have no history, your company
> CANNOT afford to use them

Documented HOW, exactly?  I mean, with the likes of Dell and Apple
issuing massive battery pack recalls due to problems, how is a small
manufacturer (or a consumer) supposed to stand a chance?

BillW

2005\12\28@210444 by David VanHorn

picon face
>
>
> "I'd like some NiMH batteries please."
> "OK, we've got some made by GP, some by Uniross, and a few just in from
> <insert name of Chinese 'amazing exploding battery' maker here>"


To make it worse, there's GP which I consider reputable, and "Gold Peak"
which I believe is a copycat, but I could be mistaken. Sort of like the
Korean camera maker "Olympos" and the Japanese "Olympus"


> "Nope, we got some a while back but we couldn't sell them.


Probably twice the price..

2005\12\28@211320 by Xiaofan Chen

face picon face
On 12/29/05, William Chops Westfield <EraseMEwestfwspamEraseMEmac.com> wrote:
> > did you ever heard some one seriously telling expensive battery
> > really give him more time of using?
> >
> I'm with "Microsoftwarecontrol."  I am merely a "consumer" when it
> comes to batteries; I don't have access to 'real' datasheets for most
> of the products, don't trust the marketing literature that passes for
> datasheets, have neither the time nor the budget to do my own testing,
> and have little faith that a "brand name" battery performs better than
> a noname brand from someplace like "batteryspace.com."  Given the way
> "US manufacturing" works, I don't even have any faith that the noname
> and name brands aren't manufactured at exactly the same factory, with
> nothing to justify the inflated price other than the fancy packaging and cute
> animated advertising...
>
> BillW
>

I'd be very careful about batteries. Lots of the no name batteries,
especially those sold in very cheap price, do leak. There are
those fake batteries. There are those expired name brand batteries.
And when they explode... Once the US$2 batteries leak and your
US$300 Digital Camera died because of the US$2 batteries, I guess
you will speak differently.

Performance may not the be the key here. The key is safety and
reliability.

Even the no name and name brand are produced by the same
factory, they still differ in the aspect of quality assurance. I once
worked in a factory building cosmetics bags for different brands and
we needed to be very careful about the orders for Chanel and
Christian Dior and other top brands. There was a bag for diamonds
and we were really very very careful.

I am not saying that all the branded product are good or of good
price-performance ratio. For example I do not buy anything from
Apple and Sony (except Sony Radios) since they are normally
over-priced. And the so-called branded in the consumer electronics
field are somewhat compromised  by the over-competition. However,
I still believe to buy from more well-known vendors and suppliers
since at least I can get some service from them.

I am afraid that this has nothing with [PIC] now.

Regards,
Xiaofan

2005\12\28@211909 by Xiaofan Chen

face picon face
On 12/29/05, David VanHorn <@spam@dvanhorn@spam@spamspam_OUTmicrobrix.com> wrote:

> To make it worse, there's GP which I consider reputable, and "Gold Peak"
> which I believe is a copycat, but I could be mistaken. Sort of like the
> Korean camera maker "Olympos" and the Japanese "Olympus"
>

GP is from Gold Peak group. They produce GP batteries and
CLIPSAL electrical installation products. The group website is here:
http://www.goldpeak.com/ and the US website is here:
http://www.gpbatteries.com/

GP batteries are okay but I guess their QA is not as good so there are
lousy GP batteries. And there are a lot fake GP batteries.

Regards,
Xiaofan

2005\12\29@014424 by Matt Pobursky

flavicon
face
On Wed, 28 Dec 2005 17:33:12 -0800, Chops wrote:
> I am merely a "consumer" when it comes to batteries; I don't have
> access to 'real' datasheets for most of the products, don't trust
> the marketing literature that passes for datasheets, have neither
> the time nor the budget to do my own testing, and have little faith
> that a "brand name" battery performs better than a noname brand from
> someplace like "batteryspace.com."  Given the way "US manufacturing"
> works, I don't even have any faith that the noname and name brands
> aren't manufactured at exactly the same factory, with nothing to
> justify the inflated price other than the fancy packaging and cute
> animated advertising...

This has been an interesting thread. Most of the designs I've done in
the past two years have been battery powered (Alkaline, NiMH, Li-Ion).
It's also interesting you mentioned batteryspace.com as I've bought and
evaluated a lot of cells from them (NiMH, Li-Ion and Li-Poly). In
general I've found the cells they sell to be very high quality and very
reliable. They also provide datasheets that are at least as good as
almost any other "name brand" battery manufacturer I've seen, if not as
slickly presented.

I'm sitting here as I type this looking at (4) AA "Powerizer" cells charging
and another prototype on my bench is running with one of their cylindrical
14500 series AA size Li-Ion cell.

Someone asked earlier about a good charger -- for AAA and AA NiMH cells I've
found the MAHA MH-C401FS charger works really well. It charges 4 cells, with
a regulated/monitored charge circuit for each cell. It has fast and standard
charge rates and yes, it has a PIC inside it.

Matt Pobursky
Maximum Performance Systems

2005\12\29@154654 by Brooke Clarke

flavicon
face
Hi:

There's a fundamental chemical difference between Ni-Cad and Ni-MH in
that the Ni-Cad does not generate anywhere as much heat at end of charge
as the Ni-MH.  Also the minus delta V for the Ni-MH is smaller than for
Ni-Cad.  So a charger designed for Ni-Cad batteries will not work on
Ni-MH.  The military Ni-Cad BB-590/U battery just has standard
electrical contacts that are used for operation and charging, but the
newer Ni-MH BB-390/U has added thermistor battery temperature monitoring.

It also turns out the the "Burp" type chargers, like the battery space
universal charger, that include a large current discharge pulse in the
charge cycle do not heat up the Ni-MH batteries like a constant current
charger does.  Alexander has uC code for their burp charger for
different uC brands for license.  More on Burp chargers at:  
http://www.pacificsites.com/~brooke/BatChg.shtml#Burp

I think it might have been "123" LiMnO2 batteries that caught fire at
LAX after they were unloaded from a flight from Japan.  The fire was
started because the fork lift operator speared the boxes just above the
skid (aircraft metal pallets are different than the wooden pallets used
on land) crushing the batteries.  For more on this see the NTSB report at:
http://www.ntsb.gov/Recs/letters/1999/A99_80_84.pdf

For a video of a Li-Ion BB-2590/U after being shot with an M-16 where
all the cells spit fire see:
http://www.valence.com/SafetyVideo.asp

Happy Holidays,

Brooke Clarke, N6GCE

--
w/Java http://www.PRC68.com
w/o Java www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com

2005\12\29@223618 by kravnus wolf

picon face
My turn. Batteries nowadays just plain suck. Not all
of them but Energizer and Duracell DO. Quality for
alkaline batteries  have declined dramatically in
these recent years! Just imagine the fluid ozzing out
of the battery after 6-9 months of use! Dremel and
sandpaper to the rescue!

Terrible. I have plenty of these problems nowadays!

John

--- Xiaofan Chen <spamBeGonexiaofancspamKILLspamgmail.com> wrote:

{Quote hidden}

> --

2005\12\30@003050 by William Chops Westfield

face picon face

On Dec 29, 2005, at 7:36 PM, kravnus wolf wrote:

> Batteries nowadays just plain suck. Not all
> of them but Energizer and Duracell DO. Quality for
> alkaline batteries  have declined dramatically in
> these recent years!

There was a rumor floating around candle power forums that
some of the brand-name batteries, having heavily advertised
"new, better formula" and gotten favorable reviews and test
results, quietly reverted to an inferior version...

Grr.  I rather survive on "kirkland" (costco's house brand)
AA's.  At about $10 for 48, they don't have to be very good
to justify the price (and the test results I've seen show them
to be pretty good, relatively speaking...)

BillW

2005\12\30@064250 by Howard Winter

face
flavicon
picon face
Bill,

On Thu, 29 Dec 2005 21:30:47 -0800, William "Chops" Westfield wrote:

>...
> I rather survive on "kirkland" (costco's house brand)
> AA's.  At about $10 for 48, they don't have to be very good
> to justify the price (and the test results I've seen show them
> to be pretty good, relatively speaking...)

I've found that for the sort of things I use them for, the Kirkland AAs last about half as long as Duracells -
and if I remember rightly Costco's price for Duracells isn't twice the Kirkland price (here in England anyway
- may not be true left-of-pond), which makes the Kirklands poor value for money.  It could be for things like
torches ("flashights") they do better, but for small electronic devices Duracells seem to be the best bet in
my experience.

The worst value I've found were so-called "Graphite" cells, which were nearly as expensive as Duracells, but
their performance was rubbish!

Cheers,


Howard Winter
St.Albans, England


2005\12\30@074634 by William Chops Westfield

face picon face

On Dec 30, 2005, at 3:42 AM, Howard Winter wrote:

> if I remember rightly Costco's price for Duracells isn't twice
> the Kirkland price (here in England anyway...

Given the nature of the "kirkland" brand; I'm not sure that
the ones sold in England are manufactured by the same company
as the ones sold in the US...

What sort of 'small electronic devices' are you talking about,
anyway?  Devising good battery tests is an art in itself!

BillW

2005\12\30@081135 by rosoftwarecontrol

flavicon
face
Big battery manufature, faked their
technology advance and faked their price
as well is obviousely. From the real test
and people's daily use, you can feel this fact.
I also believe, the so many people following
AD to buy, then following the momentum
of their meney following to judge, will
real encourage the monopolistic guy to
go further. "Word" -> "People" -> "More Word"
-------> "Money following" as side effect people
don't realize.

I notices another fact it may directly indicate
big manufacture didn't do so much research
that could give them so much technology
advance as in their word. The lack of technology
information and serious test results, about
batteries! For me, I found it is very "drowning"
situation when I tried to search test result and
technique reference about how battery
conducted during various condition. About
battery, seems just no bady really do deep and
really revealling test. I must point out,
patent and technique secret could not be decisive reason for
lack of the information.




{Original Message removed}

2005\12\30@113810 by David VanHorn

picon face
Consumer batteries suffer from the aspirin syndrome.  Each brand is much
better than any other brand.

2005\12\30@121941 by Marcel duchamp

picon face
David VanHorn wrote:
> Consumer batteries suffer from the aspirin syndrome.  Each brand is much
> better than any other brand.


I once worked on a datalogger that used 6V alkaline lantern batteries.
At the time we were using Duracell brand.  One day, a tech noticed that
a new batch seemed to be lighter than previous batteries. We opened one
up and  it's cells were 2/3's the size of previous ones and measured
around 2/3's of the capacity.  The price oddly enough was not reduced.

We enquired to the distributor who faxed a letter from Duracell.  It
explained that the new cells were "to better align the product with
consumer desires and usage patterns".  The letter was marked proprietary
- not for disclosure to the public.


2005\12\30@151512 by David VanHorn

picon face
>
> We enquired to the distributor who faxed a letter from Duracell.  It
> explained that the new cells were "to better align the product with
> consumer desires and usage patterns".  The letter was marked proprietary
> - not for disclosure to the public.


Slime. (them)

2005\12\30@193934 by William Chops Westfield

face picon face

On Dec 30, 2005, at 9:19 AM, Marcel duchamp wrote:

> We opened one up and  it's cells were 2/3's the size of previous
> ones and measured around 2/3's of the capacity.

It used to be common practice for D-sized rechargeable batteries
(back in the NiCd days) to contain the same internals and have the
same capacity as C-sized batteries from the same company.  I recall
a Consumer Reports review that pointed this out (the D cells were
even documented as having the same capacity as the C cells), and
gave high marks to Radio Shack (of all places) as one of the few
"manufacturers" that did NOT do this!

BillW

2005\12\30@204726 by Russell McMahon

face
flavicon
face
> At the time we were using Duracell brand.  One day, a tech noticed
> that
> a new batch seemed to be lighter than previous batteries. We opened
> one
> up and  it's cells were 2/3's the size of previous ones and measured
> around 2/3's of the capacity.  The price oddly enough was not
> reduced.

I bought "Sony" AA NimH from an erstwhile reputable NZ dealer.
They were far lighter than other brands.
Also far lighter than Sony said they should be.
Also far lower capacity and failed more quickly in use.
Essentially indistinguishable visually.

Sony NZ didn't care.


           RM



'[PIC]: PIC based NiMH charger'
2006\01\03@071820 by Alan B. Pearce
face picon face
>and if I remember rightly Costco's price for Duracells isn't
>twice the Kirkland price (here in England anyway - may not be
>true left-of-pond), which makes the Kirklands poor value for money.

I believe there is an annual membership fee for Costco here, have you
factored this in ?? ;)

2006\01\03@082123 by Howard Winter

face
flavicon
picon face
Alan,

On Tue, 3 Jan 2006 12:18:18 -0000, Alan B. Pearce wrote:

> >and if I remember rightly Costco's price for Duracells isn't
> >twice the Kirkland price (here in England anyway - may not be
> >true left-of-pond), which makes the Kirklands poor value for money.
>
> I believe there is an annual membership fee for Costco here, have you
> factored this in ?? ;)

No, because I pay it anyway, regardless of whether I buy any batteries!  :-)  (I believe there's a membership
fee for Costco anywhere, not just here).

And since we were discussing Kirkland (Costco's own brand) there is no point considering other aspects than
buying from Costco...

Cheers,


Howard Winter
St.Albans, England


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