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Home made charger? — Parallax Forums

Home made charger?

roughwireroughwire Posts: 78
edited 2008-01-19 14:12 in Robotics
I recently came across a decent sized battery that I took out of an old RC plane controler. Well, it's a "Sanyo 'cadnica' model 8N-600AA, 9.6V 600mAh". Well, just as well as everyone else on this little rock we call earth, I too love rechargable batteries, but I don't have a charger for it. I was wondering if I could make my own? I am still a rookie, but I was wondering if there was a simple project that I could make on little $. I once asked the same question about a small Lithium-ion battery, and was told that it was·nearly impossible, but is it possible with this type of battery? Thank you.

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MIKE

Comments

  • David H.David H. Posts: 78
    edited 2008-01-14 17:42
    Mike,
    First off, I'm not an expert in this. But you can charge this battery with a wall-wart type transformer, as long as it's a large enough output voltage. The Amperage will determine how long it will take to fully charge the battery. Just make sure you get the polarity right. That being said,... without the proper circuitry to monitor the charge of the battery, it would be VERY easy to overcharge the battery, which will heat it up, and decrease the lifespan of the battery. I'm sure this could cause some batteries to leak, melt, explode,.. take your pick. If you are like me,... I tend to forget about a charging battery,... I have overheated a couple batteries. It's basically try at your own risk. My idea is without trying, the battery is useless, unless you can locate the proper battery charger. What every you decide, good luck.

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    David


    There are 10 types of people in this world,...
    Those that understand binary numbers, and those that don't!!!
  • FranklinFranklin Posts: 4,747
    edited 2008-01-14 18:27
    http://www.uoguelph.ca/~antoon/gadgets/ccharger.htm

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    - Stephen
  • roughwireroughwire Posts: 78
    edited 2008-01-14 23:35
    wow, thanks Stephen, that schematic is almost identical to the one I just came up with. Let's say that I have about 20VDC coming out of my bridge rectifier, I then drop that down to 12v through a voltage regulator, after that, I'd use a resistor (probably a couple to compinsate for the wattage), then all I'd have to do is connect it to the battery right? Let me see if I can find that diagram I drew...

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    MIKE
  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-14 23:59
    Sounds like a nickel cadmium battery pack (cad-nica).· You can usually charge them indefinitely at 1/10 of their current capacity.· In your case, with 600mAh, you could charge them at 60mA.· Look at the datasheets for the voltage regulators you have available.· Many of them show a configuration for current regulation.· The "old standby", the LM78xx series regulators always had that and they gave a formula for calculating the resistors for a given current.
  • roughwireroughwire Posts: 78
    edited 2008-01-15 07:25
    Could this work?
    P.S. The reason for the 5 resistors is simply because I don't have any 1 or 2 ohm resistors...

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    MIKE
    bmp
    bmp
    charge.bmp
    1M
  • KMoffettKMoffett Posts: 7
    edited 2008-01-19 14:12
    A better design for 3-terminal regulators as "constant current" chargers is attached.

    Ken

    Post Edited (KMoffett) : 1/19/2008 5:22:50 PM GMT
    ConstantCurrentCharger.jpg
    346 x 338 - 16K
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