Need Solar charge control circuit help. 12v Batt (Pb)

Discussion in 'Homework Help' started by DJRCB, Feb 2, 2015.

  1. DJRCB

    Thread Starter New Member

    Feb 2, 2015
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    Hi guys im new to the site :) i was hoping to find some help/advice.

    im building a DIY portable speaker system. Im planing on adding a solar panel to charge the batt. and/or power the amp/devices. im looking to charge a 12v lead acid batt. (2.3ah) my amp circuit is aprox 6-7W max power output.

    the solar panel im looking at is either:
    1 - 12v 250ma 3W
    2 - 12v 170ma SCC 5 w

    i was thinking of using this circuit for my charging management. but im not sure if if should keep the circuit as is or modify? the circuit is designed for a 1A solar panel, mine will be a 1/4 of that. if anyone could recommend any changes (if needed) i would greatly appreciate it

    cheers
    Roy

    SPEC: LT3652

    1A Solar Panel Powered 3-Stage 12V Lead-Acid Fast/Float Charger; 1A Charger Fast Charges with CC/CV Characteristics Up to 14.4V; When Charge Current Falls to 0.1A Charger Switches to 13.5V Float Charge Mode; Charger Re-Initiates 14.4V Fast Charge Mode if Battery Voltage Falls Below 13.2V and Trickle Charges at 0.15A if Battery Voltage is Below 10V; 0°C to 45°C Battery Temperature Charging Range

    [​IMG]
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    You may regret building a switcher which is feeding low-level audio circuit. If it were me, I'd be looking at a linear regulator shunt regulator. A shunt regulator wastes no power until the battery is fully charged. Here is a long-running thread on another forum dealing with a solar shunt regulator.

    You need to check on a suitable panel. To charge a 12V SLA, you need a panel that puts out an open-circuit voltage of nearly 20V, 17V min. It should put its rated current into ~14V to properly charge the SLA.
     
  3. DJRCB

    Thread Starter New Member

    Feb 2, 2015
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    specs on the solar panel
    Output voltage: 12V - no load 27V
    Output current short circuit: 170mA
    Power: 5W

    what is the worst case scenario of using this charge managment IC? could you give my a mock up of a solar shunt regulator for my needs?

    thanks for the help.

    Roy
     
  4. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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  5. DJRCB

    Thread Starter New Member

    Feb 2, 2015
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    i wish i could use a pre-fab device. this project also is a project im doing for school.
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    a 'charging circuit' in this case could be just a simple 1N4001 diode between panel and battery.
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Already did.
    Already did, and since this is a school project, what are you going to do?
     
  8. DJRCB

    Thread Starter New Member

    Feb 2, 2015
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    I need to design something more involved than a this :)

    What do mean?

    Will the circuit that I provided work to charge a batt, If the panel provides much less than the max (1A I ) the design calls for?
     
  9. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    any current supplied to the battery with a higher voltage than the battery supplies will "charge" the battery.

    the question becomes one of quantity. how many amp hours of current is taken from the battery vs how many amp hours of current is replaced by the charger?
     
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