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Battery Charger ( A little lead and a little nickel) — Parallax Forums

Battery Charger ( A little lead and a little nickel)

ArchiverArchiver Posts: 46,084
edited 2002-03-12 18:34 in General Discussion
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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Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-03-12 03:07
    For NMH and Nicad's there have been a number of articles on this in various
    RC model airplane and RC car magazines. You might run a internet search on
    those and see what happens. The RC car racing people go into tremendous
    detail on batteries, where they even match up individual cells to get the
    maximum power for a race. The RC electric contest people for airplanes do
    pretty much the same thing.

    The basic method is to apply a voltage and and limit the current and watch
    for the peak voltage and stop when you hit the peak. You also watch the cell
    temperature to ensure you don't overheat them, when a cell is charged then
    the excess current gets rapidly turned into heat.
    The newer method is to pulse charge the cells instead of a steady DC charge
    rate. But the trick is to watch and track the voltage during charging.
    You'll hit a peak voltage when the cells are fully charged, right after that
    the voltage takes a dip. The sub C cells are typically rapid charged in
    about 15 minutes to 30 minutes. But in this case your using cells designed
    for that high charge rate. Regular slow charge cells can be charged at a
    safer 1 hour rate.

    A similar method is used to discharge the cells, except that when the cell
    discharges to 1.1 volts you stop. In RC racing you want all the cells to be
    at a known point before you charge them up again.

    Some things to look at to get you started.
    http://loke.as.arizona.edu/~ckulesa/nicads.html

    http://www.gtechno.com/gstcf.htm

    http://www.thiel.com/damien/newton_battery_FAQ.html

    And you can do a search for "nicad battery charger schematic" and get a lot
    of hits too.

    Original Message
    From: Christopher C Dundorf [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=jXyooFR6ZBJlyLn4-6BY8Wj7-V43Mi6IrZs5KCVqVJubrGFbOkQeQSwI2rqsLytxiSAW0UtEtDA]cdundorf@j...[/url
    Sent: Monday, March 11, 2002 8:22 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Battery Charger ( A little lead and a little
    nickel)


    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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  • ArchiverArchiver Posts: 46,084
    edited 2002-03-12 05:36
    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]
  • ArchiverArchiver Posts: 46,084
    edited 2002-03-12 18:34
    you might want to look at the maxim ic site www.maxim-ic.com they make a charger
    chip for both types of batteries.
    as I remember the part number is max713.

    Christopher C Dundorf wrote:

    > 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).
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