Balancing solar panel to battery in a solar charger

Harshaw
Harshaw Registered Users Posts: 1
in Advanced Solar Electric Technical Forum #1
I am attempting to put together a solar battery charger to recharge batteries that are used to illuminate 24 LEDs. The dicharge time frame is the typical sunset to sunrise time (approximately 12 hrs. The solar cell is a 6 volt 4.2 watt. Charge time frame is sunrise to sunset. Do I need to use electronics that include a charge controller, or is a simple diode system sufficient. I tried an SPV1020 chip that has a .3v to 5v window. However I seem to get better results using a simple diode and a lead acid battery than I did from a charge controler and a lithium-ion battery pak. Can anyone address this issue and provide directions on how to optimize the performance of the solar/LED fixture?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,683 admin
    #2
    Re: Balancing solar panel to battery in a solar charger

    It depends... You will probably have longer battery life if you use a "proper" solar charge controller over just wiring up a solar panel directly to the battery.

    For small/cheap systems, they use solar panels with Vmp~15 volts instead of ~17.5-18.5 volts (used with charge controllers).

    There are landscape lighting controllers like this one:

    wind-sun_2203_41590369SunLight 10 Amp 12 Volt Solar Lighting Controller

    Which will do both the charge controller and lighting timer function (uses solar array as "sunset detector").

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Balancing solar panel to battery in a solar charger

    bb,
    i don't think the sunsaver will work for a 6v system. we don't know what kind of capacity is on the battery or what type it is that you are attempting to charge to know if the solar without regulation will hurt it. a regulator chip outputting less than the battery voltage certainly won't suffice. i am not familiar with the lithium ion batteries well enough to comment unless the capacity you have is too low to operate properly. only you can see if that is the case.
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