Battery Charger --Lithium?
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Posts: 46,084
Re controlling chargers. We use rechargeable lithium batteries in r/c racing
sailboats. Lithium cells save a lot
of weight, and this might interest some stamp enthusiasts with airborne or
weight-critical robot applications.
For a 6 volt AA pack, the weight saving over NiCads is 3 ounces, which is
significant in a 16 oz racing boat hull
-- but the batteries are hard to source and tricky to charge. We buy "special"
chargers, and I know from
experience that a conventional NiCad charger will instantly exterminate a
lithium battery. But why? Would
appreciate any insights on how a lithium or lithium ion charger operates.
Some people claim it is possible to recharge an ordinary 1300 maH lithium camera
battery from Radio Shack, even
though it is not sold as a rechargeable. Is this plausible?
Many thanks, Michael
Ben Lennard wrote:
> To get an idea of what you need to do, visit my site,
> http://www.lennard.net.nz , and click on electronics, then my fast charger
> design.
>
> That design is for NiCads, but NiMH batteries have the same charging
> characteristics, so it will work for them as well.
>
> NiCads/NiMH batteries, have the characteristic that when they are fully
> charged, the voltage across them starts to fall again if continually
> charged. So, your circuit, whether based on my design, or using a Stamp,
> will just need to look for that peak.
>
> Ben, Wellington, NZ.
>
> --
> http://www.lennard.net.nz/
> Ben Lennard, NCEE, Dip EE
>
> Web Hosting and Electronics R&D
> Club Coordinator, Victoria University of Wellington Hockey Club
>
> Hm: +64 4 972 7567
> Mb: +64 21 536 627
> 87 Spencer Street
> Crofton Downs
> Wellington
> New Zealand
>
> "To the optimist, the glass is half full. To the pessimist, the glass is
> half empty. To the engineer, the glass is twice as big as it needs to be."
>
> No animals were harmed in the transmission of this email, although the
> Dog next door is living on borrowed time, let me tell you! Those of you
> with an overwhelming fear of the unknown will be gratified to learn that
> there is no hidden message revealed by reading this warning backwards.
>
>
> From: Christopher C Dundorf <cdundorf@j...>
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Battery Charger ( A little lead and a little nickel)
> Date: Tue, 12 Mar 2002 3:22 PM
>
> Hi Stampers,
>
> I've got two battery types that I need to charge. One is a 12volt lead
> acid gel (1 to 2 Ah) and the other is 12 volt nickel metal hydride (1.8
> Ah). My first question is what is the correct way to charge these
> (voltage, current, duration). Secondly, does anyone have ideas (designs)
> on using the stamp to control charging of these battery types? I envision
> a great stamp project here contolling and monitoring voltage, current,
> temp? Who knows what else.
>
> Chris
>
> ________________________________________________________________
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> [noparse][[/noparse]Non-text portions of this message have been removed]
>
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sailboats. Lithium cells save a lot
of weight, and this might interest some stamp enthusiasts with airborne or
weight-critical robot applications.
For a 6 volt AA pack, the weight saving over NiCads is 3 ounces, which is
significant in a 16 oz racing boat hull
-- but the batteries are hard to source and tricky to charge. We buy "special"
chargers, and I know from
experience that a conventional NiCad charger will instantly exterminate a
lithium battery. But why? Would
appreciate any insights on how a lithium or lithium ion charger operates.
Some people claim it is possible to recharge an ordinary 1300 maH lithium camera
battery from Radio Shack, even
though it is not sold as a rechargeable. Is this plausible?
Many thanks, Michael
Ben Lennard wrote:
> To get an idea of what you need to do, visit my site,
> http://www.lennard.net.nz , and click on electronics, then my fast charger
> design.
>
> That design is for NiCads, but NiMH batteries have the same charging
> characteristics, so it will work for them as well.
>
> NiCads/NiMH batteries, have the characteristic that when they are fully
> charged, the voltage across them starts to fall again if continually
> charged. So, your circuit, whether based on my design, or using a Stamp,
> will just need to look for that peak.
>
> Ben, Wellington, NZ.
>
> --
> http://www.lennard.net.nz/
> Ben Lennard, NCEE, Dip EE
>
> Web Hosting and Electronics R&D
> Club Coordinator, Victoria University of Wellington Hockey Club
>
> Hm: +64 4 972 7567
> Mb: +64 21 536 627
> 87 Spencer Street
> Crofton Downs
> Wellington
> New Zealand
>
> "To the optimist, the glass is half full. To the pessimist, the glass is
> half empty. To the engineer, the glass is twice as big as it needs to be."
>
> No animals were harmed in the transmission of this email, although the
> Dog next door is living on borrowed time, let me tell you! Those of you
> with an overwhelming fear of the unknown will be gratified to learn that
> there is no hidden message revealed by reading this warning backwards.
>
>
> From: Christopher C Dundorf <cdundorf@j...>
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Battery Charger ( A little lead and a little nickel)
> Date: Tue, 12 Mar 2002 3:22 PM
>
> Hi Stampers,
>
> I've got two battery types that I need to charge. One is a 12volt lead
> acid gel (1 to 2 Ah) and the other is 12 volt nickel metal hydride (1.8
> Ah). My first question is what is the correct way to charge these
> (voltage, current, duration). Secondly, does anyone have ideas (designs)
> on using the stamp to control charging of these battery types? I envision
> a great stamp project here contolling and monitoring voltage, current,
> temp? Who knows what else.
>
> Chris
>
> ________________________________________________________________
> GET INTERNET ACCESS FROM JUNO!
> Juno offers FREE or PREMIUM Internet access for less!
> Join Juno today! For your FREE software, visit:
> http://dl.www.juno.com/get/web/.
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
> Body of the message will be ignored.
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Comments
>Re controlling chargers. We use rechargeable lithium batteries in r/c
>racing sailboats. Lithium cells save a lot
>of weight, and this might interest some stamp enthusiasts with airborne or
>weight-critical robot applications.
>
>For a 6 volt AA pack, the weight saving over NiCads is 3 ounces, which is
>significant in a 16 oz racing boat hull
>-- but the batteries are hard to source and tricky to charge. We buy
>"special" chargers, and I know from
>experience that a conventional NiCad charger will instantly exterminate a
>lithium battery. But why? Would
>appreciate any insights on how a lithium or lithium ion charger operates.
>
>Some people claim it is possible to recharge an ordinary 1300 maH lithium
>camera battery from Radio Shack, even
>though it is not sold as a rechargeable. Is this plausible?
Ignoring the chemistry of lithium button cells vs lithium cells intended
for recharge, lithium batteries require *very* careful charging. If you
exceed a certain voltage, depending on the design of the cell, and I mean
if you exceed it by less than 0.1 volts, lithium cells can explode like
bombs. That's why it's so hard to source them. The individual
rechargeable cells aren't supposed to be sold directly to end
users. They're supposed to be sold only as an assembled battery
pack. These battery packs contain electronics that prevent
overcharge. Anyone who is rolling his own lithium-ion battery packs is
asking for serious trouble.
73 de Jim, KB3PU