usb backup power from large battery

[johnathon007]

I have a 6V 9.5 AH battery from a kid car and i was just wondering how to make a solar recharger and usb power from it. i already have a solar panel assembled that can charge it [almost 2 days from empty to full but it takes a lot to drain it that far] I want to use as small of a circuit as posible and i prefer ICs in my builds if possible or even needed. this isnt going to need to power anything wierd just a nice backup for my phone and mp3 player while camping or just when im not around my computer so not a huge amount of discharge cycles or crazy loads.

 

[johnathon007]

doesnt anyone know how to do this ? ive googled it but cant find anything for a battery this large

 

[Mishael]

well someone PLEASE correct me if i am wrong, but, your amp hours are just how much power is contained in the battery. now, all you really need is to change the voltage and your USB device should be powered just fine and draw what power is needed. what i suggest (this is just what some crazy student thinks who wants to help): voltage regulator, fuse, thats it. as for your solar panels, what is your amperage going in? with a charge time of that long, i think you could be safe with a larger amperage

 

[Oznog]

Well, you just need a low-dropout 5v regulator and 2 appropriate caps for the reg.

The solar panel probably doesn't need a charge controller, because the current is too low to significantly overcharge the batt. You may want a blocking diode because the solar panel will leak current out of the batt when dark if it's connected without it.

 

[johnathon007]

Thats what i thought but i just wanted to be sure before i tried it incase i was wrong , i didnt fell like betting my mp3 player or phone on it thanks and my panel is a around 10 volts 800mA in full sun , it charges the battery to 70% or so withing a few hours but then it goes really slow. And i heard that i could just use a diode to drop the voltage and i wasnt sure how correct that is, any info on that ? I was going to rip up an old PC power supply to see if i could find some goodies in there for this.