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How to protect the battery from being over-used and overcharged!!!???

Discussion in 'Power Electronics' started by Shine, Jul 29, 2012.

  1. Shine

    Shine

    16
    0
    Jul 29, 2012
    Hi friends,

    I am a new member here and an environmentalist from Burma and a new starter in electronics. I am designing a solar powered LED circuit with a 4V, battery. How do I build a circuit that protects the battery from being overcharged and overused??? Please, help me with this. Any answer would be much appreciated!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,043
    1,812
    Nov 17, 2011
    Please give more information:
    - what are the characteristics of the solar array (voltage, current)?
    - what are the characteristics of the battery (type of battery, capacity)?
    - what are the characteristics of the load (voltage, current)?

    Generally;
    Use a "battery charger IC" to charge the battery. The IC has to match the type of battery you are using. Many IC vendors have such ICs, use Google and the cuewords in quotes.
    For discharge protection you can use a simple comparator or Google "battery discharge protection".
    You may also want to Google "photovoltaic battery charger ic".

    Ready made controllers can be found using "solar battery charger" in Google, e.g. http://www.powerstream.com/pv-control.htm

    Dpending on your requirements (reliability, price, ease of handling etc.) such a project is probably not the best idea for a starter project.

    Harald

    P.S.: And please fon't post the same question twice.
     
  3. Shine

    Shine

    16
    0
    Jul 29, 2012
    Many, many thanks for the answer!!! I already knew the project would not be easy for a starter but millions of poor households in our country still uses oil lamps and candles. What I would like to make is the low cost solar powered LED light(light output is fine) to introduce the rural poor.

    I would like to provide more information regarding my previous question.

    Solar type - CIS 1W, maximum output 8.5 V, 0.2 mAh
    Battery - 4V/4Ah lead acid battery
    LED bulb - 4V/1W

    Many thanks again for answers and advices!

    Shine
     
  4. donkey

    donkey

    1,286
    56
    Feb 26, 2011
    you could start with solar garden lights if you have a few bucks spare. these are very dim (especially the cheap ones) but they have all of the components already. take one of these apart and try to learn each part and improve on them. My advice would be starting on the light, get the right light output first
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    9,043
    1,812
    Nov 17, 2011
    Here is a charger for lead acid batteries from solar panles: http://www.den-uijl.nl/electronics/solar.html
    It is designed for 12 V batteries, but is adjustable. Maybe you could consider using 12 V batteries an option as they are easy to come by (car or motorbike batteries)?

    You could use a step down-converter to drive the LED. However, I wonder what kind of LED bulb this is. 4 V is an unusual operating voltage for a bulb. Could it be that you have a bare LED rated 4 V? In that case you will need a current limiting circuit, in the most simple form a series resistor. Read the section on LEDs in this forum.

    Building a battery charger that will ensure a long life of the battery is not a trivial task. A good circuit can be rather expensive. Donkey's advice is a good one.
     
  6. donkey

    donkey

    1,286
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    Feb 26, 2011
    I have my moments... few and far between, but I do have them
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    9,043
    1,812
    Nov 17, 2011
    Nay, fishing for complements;) ?
     
  8. donkey

    donkey

    1,286
    56
    Feb 26, 2011
    not me lol. I actually have started using a part of my brain a bit more, since I have been on here, that hasn't been used for a while. look at the arduino post I did for the X guy... took me a while to figure out how to get the off switch but I got there lol
     
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