>-----Original Message-----
>From: spam_OUTpiclist-bouncesTakeThisOuTmit.edu [.....piclist-bouncesKILLspam@spam@mit.edu]
>Sent: 15 August 2005 14:51
>To: Microcontroller discussion list - Public.
>Subject: [EE] Detection of Alkaline batteries in a charger
>
>
>Anyone know of a method of detecting if a battery that is
>inserted into a charger is alkaline or nicad/niMH?
Possibly internal resistance coupled with terminal voltage might be useable. i.e. a fresh alkaline cell will have a higher terminal voltage than even a freshly charged nicd/nimh. For simmilar terminal voltages, I would expect the alkaline cell to have significantly higher internal resistance than a nicd/nimh (and nimh has 2-3 times higher internal resistance than nicd). This would need to be born out by experimental and/or manufacturers data of course.
Of course, telling the difference between a duff nicd/mh and an alkaline cell in this manner may be impossible ;)
Regards
Mike
=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
> Anyone know of a method of detecting if a battery that is
> inserted into a charger is alkaline or nicad/niMH?
apply a square-wave load, observe the voltage difference, estimate
source resistance? AFAIK the source resistance of NiCad is *much* lower
than a compareable alkaline. But you might get introuble distinguishing
a very small NiCad from a large alkaline.
Wouter van Ooijen
-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu
> Anyone know of a method of detecting if a battery that is inserted into a
> charger is alkaline or nicad/niMH?
Drive the battery with AC.
Mount a capacitive plate facing the side of the battery.
If the received signal from the plate is in phase with the positive pole,
it's alkaline.
This works because the outer case of alkaline batteries is positive,
nicad/nimh have negative case.
Whether you can get it to work in practice is an excercise left to the
experimenter.
What do you want to bet someone has attempted to patent this idea already?
If not, the piclist will count as prior art, please give me credit :)
>-----Original Message-----
>From: piclist-bouncesKILLspammit.edu [.....piclist-bouncesKILLspam.....mit.edu]
>Sent: 15 August 2005 17:28
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] Detection of Alkaline batteries in a charger
>
>
>> Anyone know of a method of detecting if a battery that is inserted
>> into a charger is alkaline or nicad/niMH?
>
>Drive the battery with AC.
>Mount a capacitive plate facing the side of the battery.
>If the received signal from the plate is in phase with the
>positive pole, it's alkaline.
>
>This works because the outer case of alkaline batteries is
>positive, nicad/nimh have negative case.
>
>Whether you can get it to work in practice is an excercise
>left to the experimenter.
>
>What do you want to bet someone has attempted to patent this
>idea already? If not, the piclist will count as prior art,
>please give me credit :)
>
>-Bob Blick
Bob,
I'm wondering if the very low internal impedance of nicd/mh would cause problems, as the positive and negative would be very closely coupled.
Regards
Mike
=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
This relates to a product that can be run off either a rechargeable pack or standard batteries. I guess another approach is to have two different battery holders. One haveing a sealed set of rechargeables, the other allowing the user to replace the standard cells. Then a sensor can detect what pack is plugged in. That might be the easiest and most foolproof method.
---------------------------------
Start your day with Yahoo! - make it your home page
>-----Original Message-----
>From: EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu [piclist-bouncesspam_OUTmit.edu]
>Sent: 15 August 2005 19:42
>To: Microcontroller discussion list - Public.
>Subject: RE: [EE] Detection of Alkaline batteries in a charger
>
>
>This relates to a product that can be run off either a
>rechargeable pack or standard batteries. I guess another
>approach is to have two different battery holders. One
>haveing a sealed set of rechargeables, the other allowing the
>user to replace the standard cells. Then a sensor can detect
>what pack is plugged in. That might be the easiest and most
>foolproof method.
This is exactly what Kodak did in a DX3700 camera I bought years ago. The special (i.e. expensive) Kodak battery pack was simply 2 AA NiMh cells with a simple plastic sleeve that operated a switch in the cammera. When they died, I simple removed the sleeve and fitted it over a couple of new high capcity cells. Not much good for a "universal" type charger though.
Regards
Mike
=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
At 12:42 PM 8/15/2005, alan smith wrote:
>This relates to a product that can be run off either a rechargeable pack
>or standard batteries. I guess another approach is to have two different
>battery holders. One haveing a sealed set of rechargeables, the other
>allowing the user to replace the standard cells. Then a sensor can detect
>what pack is plugged in. That might be the easiest and most foolproof method.
One piece of consumer equipment I worked on years ago (Sony? don't
remember) did something similar: the charging contacts made connection
through a cut-away portion of the cell's outside insulating sleeve. Seemed
like a workable solution at the time.
In more modern times, the battery pack connection for RTS wireless intercom
belt packs (division of Telex) have 3 contacts. The battery sled intended
for alkaline cells uses only two of those contacts; the sealed rechargeable
battery packs have all three contact positions populated. I haven't looked
inside but I'm guessing the 3rd contact is to a thermistor and provides
both rechargeable pack identification as well as cell temperature.
Celebrating 21 years of Engineering Innovation (1984 - 2005)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
>>Drive the battery with AC.
>>Mount a capacitive plate facing the side of the battery.
>>If the received signal from the plate is in phase with the
>>positive pole, it's alkaline.
>>
>>This works because the outer case of alkaline batteries is
>>positive, nicad/nimh have negative case.
A superb idea. But do note that Zinc-Chloride and leClanche (much the
same but different) have negative outer shells.
I built a toaster-tester once that determined if one of the two
switches in each main slead was stuck on (as some were). It measured
capacitance between the two mains pins. joined together and the ground
pin. Stuck switch gave far higher capacitance.
On Mon, 15 Aug 2005 10:39:13 -0400, Olin Lathrop wrote:
> alan smith wrote:
> > Anyone know of a method of detecting if a battery that is inserted into
> > a charger is alkaline or nicad/niMH?
>
> If it blows up and makes a mess after charging it was an alkaline.
However if it blows up and wrecks the room, it was Lithium! :-)
mit.edu [.....piclist-bouncesKILLspam
