14th March 2012 06:36 PM
Hello everyone I am making a solar rechargeable battery USB thing. I got all the parts and I know that a USB out put Is about 5V and is .500mAmps. My solar plane out put is about 6V and it's current is about 1amps. My batteries are two D cell and there out put together are about 2.5 and it's current is about 7.6Amps. I connect my solar plane to a Diode to stop the flow to go back which then is connect to the postive connection of my battery holder then to a resistor (4.7) which lowers the current to about .550mAmps. Which will go to my female side of the USB. and then complet the circuit by connecting the negative to the negative end to the battery holder and solar plane. Now the problem is that my friend is saying that I need to add a voltage limitar on it right between the solar plane and the battery holder. If I do how would do this?
P.S i know I need to double the batteries and the resistor but overall do i need the voltage limitar in it or no?
Last edited by Dragonsniper108; 14th March 2012 at 08:07 PM.
14th March 2012 09:17 PM
The rechargeable battery cells limit their voltage. But you need something to detect a full charge then reduce the current to a trickle.
14th March 2012 09:21 PM
how do I do that please explain thanks or should I make a LED detection thing that will tell me when it is fully charge (still don't know how to make (-_-))
Originally Posted by audioguru
Last edited by Dragonsniper108; 14th March 2012 at 09:34 PM.
14th March 2012 10:41 PM
Most people use a battery charger IC to properly charge a battery. Maxim and many other semiconductor manufacturers make them.
15th March 2012 12:01 AM
thanks but I still don't know how to put that into my circuit
15th March 2012 12:12 AM
To properly charge a battery then use a battery charger IC. Its datasheet will show how to do it.
Originally Posted by Dragonsniper108
Pick a battery charger IC for the type of battery you have (lead-acid, Ni-Cad, Ni-MH or Lithium).
15th March 2012 02:17 AM
15th March 2012 10:04 AM
You need to connect the solar panel to the D cells (via a diode) and include a multimeter set to current.
Pick a sunny day and let us know the current after about 30 minutes. Then we can advise you of the value of a simple current-limiting resistor or otherwise.
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