solar battery charger 9v panel to 4AA batt's

Discussion in 'The Projects Forum' started by cnatsu1, Sep 15, 2013.

  1. cnatsu1

    Thread Starter New Member

    Sep 15, 2013
    Newbie here. I have a basic understanding of electronics, probably just enough to get me in trouble. I'm playing with making a battery charger with a 9v, 1.5W, 167mA solar panel I found on clearance at radio shack. I've watched numerous videos and read numerous articles on making one, but need some expert advice.

    Today I hooked up my panel straight to a 4aa battery pack w/ 1.2v 2500 mA rechargeable batteries with only a 1n914 diode in series on the positive. My voltage output from the panel disconnected is 9v but as soon as I connect it to my battery pack it drops to 5.5. Is that too much for my battery 4.8 combined voltage requirement??

    I know that to avoid battery damage I shouldn't pump more than 10% (250mA) of the battery capacity in current. Under a bright sun I was only getting approx 80mA with my batteries connected. So I'm thinking I should be safe adding another solar panel to push up to 160mA???

    My original goal was to make a solar battery charger that I could then use to charge my cell phone via usb cable. I was looking at getting a lm317t voltage regulator chip to drop the voltage and stripping a car usb car charger to use for my output once the batteries are charged. Now after looking at my voltages and current the lm317t doesn't seem necessary??

    Thanks in advance. Remember, newbie - I won't understand a really technical engineereze response.
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    Need to know what type of batteries--Ni-Cd, Ni-MH,or ?.
  3. cnatsu1

    Thread Starter New Member

    Sep 15, 2013
    looks like the ones I had in the closet are Energizer NiMH. What's going to be the best type for an easy setup??
  4. wayneh


    Sep 9, 2010
    You might consider looking at a DC-DC buck-boost converter such as the ones you can find on e-bay. They're reasonably efficient, very cheap, and solve the problems of matching one voltage to another.