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charging one battery from another (using a charge controller, natch)

Discussion in 'Electronic Design' started by [email protected], Mar 28, 2007.

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  1. Guest

    I'm thinking about the simple scheme of charging a portable device's
    rechargeable internal battery from an external battery (which should
    have a little higher voltage, obviously). The portable device should
    have an internal charge controller to protect its battery and manage
    the charging.

    Find a suitable battery or stack of cells, and plug it in. Simple.

    Using AA cells in an product like Belkin's iPod charger is an
    Recharging your cell phone from your car's 12V battery could be an
    example. Emergency power for a cell phone would be an example.
    Instances of externally powering the dead device, without
    significantly charging its battery, would be interesting as well.

    I'm looking for specific instances of products, or of people doing
    themselves and making the suggestion to others. One caveat, these
    instances have to be during the 1990s or before. Sorry! :) That
    rules out Belkin and their AA-cell holder, since Apple introduced the
    iPod in 2002 and they brought out their product sometime later.

    Thanks, Win.
  2. Guest

    I believe those miniature R/C racing cars used this approach. You
    know, those 1 inch long cars?
    I know R/C electric helicopters use this approach as well.
    I suspect it started some time in the 90s.
  3. Fred Bartoli

    Fred Bartoli Guest

    a écrit :
    Electric RC racing cars do this all the time from car batteries.
    Remember this from when I was a teen (end of 70s).
  4. James Arthur

    James Arthur Guest

    Here are two leads--both unsure--for you:

    1) I got an Acon "Power Runner" that fits this description from a
    swapmeet, but when was it made? Hmmm. Let's take a peek inside.
    [fetch, apply implements of destruction] No obvious date codes,
    except some on a Philips LM358D which I can't interpret. Hmmm...
    aha!, from an obscure page on their website: it was designed in 2001.

    2) Radio Shack had universal power gizmo that I nearly got on close-
    out several years ago. I don't remember what they called it.

    It could use either wall-power or d.c. in, and held 4xAA cells,
    IIRC. It could charge those 4xAAs from external a.c. or d.c. power,
    and could supply an external device with a switchable/selectable
    voltage from, as I understood it, any of the three power sources
    (i.e., DC-DC, AC-DC, or battery-to-DC). Its literature suggested it
    as useful to recharge other portable, d.c.-input devices.

    I picked it up and put it down a few times, considered, then
    ultimately left it. Since this was at least 4-5 years ago, and on
    close-out, it might have been introduced within your timeframe. Maybe
    they have a manual in their archives?

    James Arthur
  5. Nice. Did it have some type of current-limiting resistor or some
    other way to control the charging from the external power source?
  6. Ah, but did the miniature RC cars contain a built-in
    current-limiting resistor or some other way to control
    the charging from the external battery?
  7. Phil Hobbs

    Phil Hobbs Guest

    ZipZaps, they're called. Fun while they last (about 3 days).


    Phil Hobbs
  8. Rich Grise

    Rich Grise Guest

  9. James Arthur

    James Arthur Guest

    Switchers all around, AFAICT. It was light, and compact--not
    noticably larger than typical 4xAA chargers.

    Once upon a time Radio Shack had an FTP site with downloadable service
    manuals--with parts lists and schematics--for all their stuff. Very
    nice. That site would be an easy place to search for info., if it
    still existed. I don't know if it does. You could also order from
    any store for just a few dollars, and they'd mail it to your home.
    Here, though, you'd first have to know what manual to order!

    Best regards,
    James Arthur
  10. James Arthur

    James Arthur Guest

    Ah, I might've misinterpreted your question. Yes, clearly the Radio
    Shack device had a controller to manage charging of its own, local
    rechargeable cells (that is, 4xAA cells installed by the user for

    The device could also use the 4xAA user-installed cells--
    rechargeable or not--as a power source, and produce selectable
    voltages to drive external devices. I assume this output was a
    voltage-source, albeit likely current-limited for safety-- and that
    any external device would be responsible for managing its own re-

    Hope that clarifies it.

  11. This device then wopuldn't be anything but a battery pack with some charge
    control circuitry and a DC output, right? A portable wall wart, sort of, for
    what is a mobile's "charger" except a wall wart?

  12. Hmmm. What could this mean? OK, here goes: Someone (A) files a patent on
    such a device in 1990. More recently, someone else (B) starts selling a
    similar contraption. A sues B for patent violation. B is now trying to find
    prior (to 1990) art in order to render A's patent void.

    So you're working for B, right?

    What constitutes prior art, anyway? An article in a hobby electronics
    magazine? One of those really productive design brainstorming threads in

  13. Why don't you post the number of the patent being contested? ;-)

  14. Fred Bloggs

    Fred Bloggs Guest

    If it's "prior art" you're looking for then you should just come out and
    say so instead of being deceitful and manipulative like this...
  15. Rich Grise

    Rich Grise Guest

    Awwww. For a minute there, I was so proud of myself....

  16. Joerg

    Joerg Guest

    And then A's investors blow a gasket and begin to sue A ...

    Either one should seriously shake a patent claim at the roots. But
    imagine what would happen if you are on the witness stand and asked how
    you know for sure. Then you quietly pull out a rechargeable flashlight
    or something like that. "Grandpa used this in his DeSoto all the time.
    He passed away in 1980." Then you can probably see harried folks
    whipping out their cell phones and storm out the court room.

    Usually stuff like this becomes so obvious during discovery that it is
    settled before heading too far towards a major embarrassment in court.
  17. James Arthur

    James Arthur Guest

    Another possibility: if you suspect a patent is invalid, you can
    request a re-examination and submit your prior art references. You
    have to pay the ~$2K re-examination fee, but it could be worth it,
    circumstances depending. This process can limit or invalidate a
    patent entirely, with no court battles required, as long as you can
    prove your point.

    James Arthur
  18. Joerg

    Joerg Guest

    Considering that you could spend that on a lawyer in under two days,
  19. Guest

    If we all assume it's a prior art search, how is it hidden?
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