Almost any battery charger.

Discussion in 'General Electronics Chat' started by hp1729, Apr 6, 2016.

  1. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    How about a battery charger that does just about any AA battery? NiCad, NiMH, rechargeable alkaline, NiZn, LiFePO4 ... maybe even LiIon batteries. I haven't tried one yet but it is in the voltage range I think. A "good" battery charger it may not be. It doesn't note the voltage drop indicating a proper full charge. It does note peak voltage, adjustable to meet the needs of various batteries. When peak voltage is reached it shuts down and lights a light.
    Other than not noting that voltage dip it breaks a few other rules. Power is about 7 V. This voltage also runs the 74LS74 TTL chip.
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
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    You have designed a nifty circuit that charges at a constant current until a voltage is reached and then it shuts off and a led comes on. Unfortunately, the world does not need another bad battery charger. Wal-Mart has beat you to it. They sell some of the worst chargers in the world. Most of the those chargers do pretty much what you have designed. Please learn about the battery chemistry before you design your next charger. Each type of battery has its own charge profile. If that profile is not followed, then not only will the battery be poorly charged, but will fail prematurely.

    Yea, my above language is a little strong, but you are a feisty kind of guy and you can deal with it. It took me a while to figure out the difference between a good battery charger and a bad one.
     
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  3. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    You are quite correct it is another less than perfect battery charger. I opted for a trade off of one charger instead of many different chargers. I couldn't find a charger at all for the rechargeable alkaline.
    No offense taken. Your analysis was correct. The objective was one instead of many.
    Maybe the next evolution will be a smart charger that handles each type correctly.
     
  4. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    They do make chargers for this purpose and pretty cheap for a quality charger..
    I tend to stay away from chargers and such cause these built unit should be watched in the event of a failure or design error and other safety concerns.. I mean look at Julian Llett with his solar chargers that are starting to show failures errors .
     
  5. MrSoftware

    Active Member

    Oct 29, 2013
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  6. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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  7. MrSoftware

    Active Member

    Oct 29, 2013
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    That's a list of multiple chargers that charge multiple chemistries. The leads connect to whatever package you have. You can probably find the guts of many of those as open source somewhere, I believe they just use a little micro processor to control the output.
     
  8. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    And a very nice list it is. My charger was made from stuff on hand. Cost $0 to build.
     
  9. Lestraveled

    Well-Known Member

    May 19, 2014
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    @hp1729
    Why don't you design a charger that correctly charges NiCad/NiMH and LiPo in the AA case size. Both battery chemistries benefit from temperature sensing. It is just a matter of adjusting crossover points. A simple switch is all that is needed. Learn each charge profile and translate it into electronics. Now, that would be cool!!
     
  10. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Dare I say you may want to think about a micro. Good sensing of Nicad and NiMd is tricky. Hard to do with just hardware.
    [​IMG]
     
  11. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    A good suggestion. Maybe in the next version. This one was thrown together as a dumb controller. The operator supplies the smarts. It would take me more than the hour this design did. I have a few options of processors to work with. I figure a 10-bit ADC is needed to note the 5 mV dip at the end of the charge cycle, assuming operation from +5 V. A stable voltage source, MZ4614 diode (1.8 V) with an LM334 constant current source should be stable enough.
     
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