AVR-Chat

Hi All,

Need some ideas on charging nicads to get the most life out of them in
low duty cycle pulsed current load and as long life as possible 

Situation is similar to a smoke alarm.

Any ideas ?

The product will have an AVR something like a Tiny15, but I do not want
to go to the extreams of the AVR app note 450 design, the device will be
selfcontained running off the 240Vac using more than likely a mains
voltage reg or capacitive divider to ~12 then zener resistive to +5v for
the AVR.

Regards,

Kat.

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At 09:28 PM 1/23/2004 +0800, Kathy Quinlan wrote:
>Hi All,
>
>Need some ideas on charging nicads to get the most life out of them in
>low duty cycle pulsed current load and as long life as possible
>
>Situation is similar to a smoke alarm.
>
>Any ideas ?

Not the best suited battery for this app.  Lead acid, with the input 
voltage set to their float spec, are probably best for long term float.

Other than that, keep the nicads charged with <0.1C maybe 0.01C if their 
delf-discharge spec says you'll be energy positive.

> -----Original Message-----
> From: Dave VanHorn [mailto:dvanhorn@cedar.net] 
> Sent: Friday, 23 January 2004 9:53 PM
> To: AVR-Chat@yahoogroups.com; AVR CHAT YAHOO
> Subject: Re: [AVR-Chat] NICAD charging cheap and long term.
> 
> 
> At 09:28 PM 1/23/2004 +0800, Kathy Quinlan wrote:
> >Hi All,
> >
> >Need some ideas on charging nicads to get the most life out 
> of them in 
> >low duty cycle pulsed current load and as long life as possible
> >
> >Situation is similar to a smoke alarm.
> >
> >Any ideas ?
> 
> Not the best suited battery for this app.  Lead acid, with the input 
> voltage set to their float spec, are probably best for long 
> term float.

I know, but trying to get a SLA of small enough capacity is hard, we are
talking of the highest load being a pizo sounder IE 50mA max and even
then it will have a duty cycle like 0.25 seconds on 10 seconds off. And
it is designed never to run ;o) only in emergencies (no a life support
or life protection so no need to worry about run durations etc) I would
say if it would run possibly for 4 hours on something like 3 AAA nicads.


> Other than that, keep the nicads charged with <0.1C maybe 
> 0.01C if their 
> delf-discharge spec says you'll be energy positive.

Yeah that is what I was planing, a perminate resistor set at 0.01C
(aprox need to read up on the specs of batteries we use) and then a fet
and lower resistor to do a charge when battery is flat and AC is on.

Regards,

Kat.

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Alkalines might be more reliable here.

There is also rechargeable alkalines from Energizer.  These can easily be
bought (at least here in the US) at your local store with a decent
electronics section.  These have saved my household a lot of money with
3-kids with gameboys, CD players, etc...

Thanks,
Dave Miller

> -----Original Message-----
> From: Dave VanHorn [mailto:dvanhorn@cedar.net]
> Sent: Friday, January 23, 2004 9:39 AM
> To: AVR-Chat@yahoogroups.com; AVR-Chat@yahoogroups.com
> Subject: RE: [AVR-Chat] NICAD charging cheap and long term.
> 
> 
> Alkalines might be more reliable here.
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> To visit your group on the web, go to:
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> 
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> 
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Dave Miller said:
>
> There is also rechargeable alkalines from Energizer.  These can easily
> be bought (at least here in the US) at your local store with a decent
> electronics section.  These have saved my household a lot of money with
> 3-kids with gameboys, CD players, etc...


Never had much luck with the rechargeable akalines here.  The best thing
to happen for Gameboys was the release of the Gameboy Advance SP.  Lighted
screen and lithium ion battery that has paid for itself in the past year
alone but not requiring regular batteries.

To get back on topic, I seem to recall someone mentioning a design for an
AVR-based cartridge copier.  Any progress on that?

Mike

Hi, Kat

    I have a product that I produce for more than 9 years and I have been
using NiCd's all this time. I tried many different brands and ended up using
Saft high temperature batteries. They are specified to work at continuous
trickle charge and really last much longer than other batteries I have tried
from panasonic and sanyo.

    Follows a link to the battery family that I use:

http://www.saftbatteries.com/120-Techno/10-10_produit.asp?paramtechno=Nickel
+systems&Intitule_Produit=VT

    I hope this helps....

Best regards,
Alexandre Guimaraes



----- Original Message -----

From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
To: "AVR CHAT YAHOO" <AVR-Chat@yahoogroups.com>
Sent: Friday, January 23, 2004 11:28 AM
Subject: [AVR-Chat] NICAD charging cheap and long term.


> Hi All,
>
> Need some ideas on charging nicads to get the most life out of them in
> low duty cycle pulsed current load and as long life as possible
>
> Situation is similar to a smoke alarm.
>
> Any ideas ?
>
> The product will have an AVR something like a Tiny15, but I do not want
> to go to the extreams of the AVR app note 450 design, the device will be
> selfcontained running off the 240Vac using more than likely a mains
> voltage reg or capacitive divider to ~12 then zener resistive to +5v for
> the AVR.
>
> Regards,
>
> Kat.
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.560 / Virus Database: 352 - Release Date: 8/01/2004
>
>
>
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
>  http://groups.yahoo.com/group/AVR-Chat/
>
> To unsubscribe from this group, send an email to:
>  AVR-Chat-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
>  http://docs.yahoo.com/info/terms/
>
>
>

While we're sort of on this subject, let me relay a little research into 
memory effect on NIMH.

http://www.dvanhorn.org/NIMH/Index.php

It's about halfway down the page.

On Fri, Jan 23, 2004 at 07:45:28PM -0500, Dave VanHorn wrote:

> While we're sort of on this subject, let me relay a little
> research into memory effect on NIMH.

> http://www.dvanhorn.org/NIMH/Index.php

> It's about halfway down the page.

Interesting.

One of the problems with maintaining rechargeables is the "memory"
effect that's certainly evident in NiCd.

If one isn't stuck for space and weight isn't a problem, then it may
be appropriate to run two battery packs in tandem; one which is the
backup supply and the other being cycled so as to avoid the memory
effect. 

Full redundancy requires 3 battery packs as the power supply
requirements to charge a NiCd to make it forgetful is quite high.
There'd be "backup", "source" and "cycle" packs.
The source battery pack is used for the initial current supply while
the voltage of the cycle pack being charged is low. The boost
current from the source battery depletes a large part of it's charge
so a backup pack is required for "fail-safe".

With just 2 cells, the backup and source batteries are the same.

The condition of the batteries can be monitored and notification
(light/audio/signal) of a failing one made by the controller.

It's a pretty obvious approach if you're looking for improved
reliability of varying degrees. Cost is an issue that must be
weighed against the benefit of increased reliability.

-- 
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Thanks for the pointer, I just rang a local battery supplier, to buy a 3
cell AAA NiCad Pack in qty's of 100 I would be looking at ~$14 (far to
much) but I can get a single cell Lion Battery with 2AH rating for $6 in
100 qty more like it lol.

He said the price difference between an 0.8Ah and 2Ah was 50c so I am
now looking at Lion charger chips lol  The LTC4054-2.4 looks nice and
simple.

Regards,

Kat.



> -----Original Message-----
> From: Alexandre Guimaraes [mailto:listas@logikos.com.br] 
> Sent: Saturday, 24 January 2004 8:42 AM
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] NICAD charging cheap and long term.
> 
> 
> Hi, Kat
> 
>     I have a product that I produce for more than 9 years and 
> I have been using NiCd's all this time. I tried many 
> different brands and ended up using Saft high temperature 
> batteries. They are specified to work at continuous trickle 
> charge and really last much longer than other batteries I 
> have tried from panasonic and sanyo.
> 
>     Follows a link to the battery family that I use:
> 
> http://www.saftbatteries.com/120-Techno/10-10_produit.asp?para
> mtechno=Nickel
> +systems&Intitule_Produit=VT
> 
>     I hope this helps....
> 
> Best regards,
> Alexandre Guimaraes
> 
> 
> 
> ----- Original Message -----
> From: "Kathy Quinlan" <kat-yahoo@kaqelectronics.dyndns.org>
> To: "AVR CHAT YAHOO" <AVR-Chat@yahoogroups.com>
> Sent: Friday, January 23, 2004 11:28 AM
> Subject: [AVR-Chat] NICAD charging cheap and long term.
> 
> 
> > Hi All,
> >
> > Need some ideas on charging nicads to get the most life out 
> of them in 
> > low duty cycle pulsed current load and as long life as possible
> >
> > Situation is similar to a smoke alarm.
> >
> > Any ideas ?
> >
> > The product will have an AVR something like a Tiny15, but I do not 
> > want to go to the extreams of the AVR app note 450 design, 
> the device 
> > will be selfcontained running off the 240Vac using more 
> than likely a 
> > mains voltage reg or capacitive divider to ~12 then zener 
> resistive to 
> > +5v for the AVR.
> >
> > Regards,
> >
> > Kat.
> >
> > ---
> > Outgoing mail is certified Virus Free.
> > Checked by AVG anti-virus system (http://www.grisoft.com).
> > Version: 6.0.560 / Virus Database: 352 - Release Date: 8/01/2004
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:  
> > http://groups.yahoo.com/group/AVR-Chat/
> >
> > To unsubscribe from this group, send an email to:  
> > AVR-Chat-unsubscribe@yahoogroups.com
> >
> > Your use of Yahoo! Groups is subject to:  
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> 
> 
> 
>  
> 
> Yahoo! Groups Links
> 
> To visit your group on the web, go to:  
> http://groups.yahoo.com/group/AVR-Chat/
> 
> To unsubscribe from 
> this group, send an email to:  AVR-Chat-unsubscribe@yahoogroups.com
> 
> Your use of Yahoo! Groups is subject to:  
> http://docs.yahoo.com/info/terms/ 
> 
> 
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> 

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>
>One of the problems with maintaining rechargeables is the "memory"
>effect that's certainly evident in NiCd.

Memory, refers specifically to the voltage droop that happens near a point 
of previously repeated discharge.
Long term overcharge causes charge depression in NIMH, but I don't know if 
that happens in Nicad.

>If one isn't stuck for space and weight isn't a problem, then it may
>be appropriate to run two battery packs in tandem; one which is the
>backup supply and the other being cycled so as to avoid the memory
>effect.

Simply sitting on charge will not induce memory in either chemistry.  It 
will induce charge depression in NIMH cells.
Cycling to a specific voltage point, is how I have induced memory previously.
I am going to try this again, discharging to a specific energy point ( say 
to 10,000J discharged perhaps) but that won't be soon.
I'm not at home.


>Full redundancy requires 3 battery packs as the power supply
>requirements to charge a NiCd to make it forgetful is quite high.

???  I haven't tested Nicad yet, but NIMH forgets the memory effect in one 
normal discharge.

>There'd be "backup", "source" and "cycle" packs.
>The source battery pack is used for the initial current supply while
>the voltage of the cycle pack being charged is low. The boost
>current from the source battery depletes a large part of it's charge
>so a backup pack is required for "fail-safe".

And now you have all this extra complexity to fail. :-P

At 08:02 PM 1/24/2004 +0800, Kathy Quinlan wrote:
>Thanks for the pointer, I just rang a local battery supplier, to buy a 3
>cell AAA NiCad Pack in qty's of 100 I would be looking at ~$14 (far to
>much) but I can get a single cell Lion Battery with 2AH rating for $6 in
>100 qty more like it lol.

Drop me an address, I can send you a bunch of 3 cell NIMH packs.