Excellent find! At the start of this thread I googled 'USB Charger' but my returns were all wall warts with USB connectors. Funny thing is.. I've been to SparkFun many times but then, I wasn't looking for these.If your battery is a single cell type battery the MAX1555 may be usefull. But it is sot23 type package. At sparkfun you can also order this http://www.sparkfun.com/commerce/product_info.php?products_id=726 it may do what you want to do.
Not quite. It is a camera battery, and one idea is to modify an existing cheapo Asian fake Sony charger that I have. I will not be attaching this device to my camera, so the only important thing that could be damaged is the battery itself (as a receiver of power).I'm finding this entire thread a bit confusing. The stated goal is to charge a cellphone battery with a solar panel, right?
If you can elaborate on how to do this, that would be helpful. But with the "panel" that I am using, it may not be a concern. (since it is designed as an integrated solar charger)You need a design that won't ruin your stuff, and the answer could be as simple as a blocking diode to prevent discharge thru the panel.
Over-voltage: Solio "panel" is 5-6V. Normally a charger for this battery gives 4.2, so it is a bit high.The first concern is over-voltage ... Next concern is over-charge ... A final concern is charge rate
The off-the-shelf Sony camera battery that I am starting with better stop giving power to the battery when it was charged. That is what chargers do, right? True it is not authentic Sony; I have another authentic Sony one and it certainly does not allow overcharging.I don't think the original charger appears to control state-of-charge, but I'm not sure
Yes, that is what the charger I am modifying gives as a charge voltage.I hope the charge voltage is setup for 4.2V as this generally represents a fully charged LiIon cell.
How do I make that low dropout regulator?I also find this confusing. From what I can see the charger shown by the OP in the first post. Is a very simple switch-mode constant voltage power supply. It is rated 4.2 volt 0.25. So all the OP has to do is to make a low dropout regulator to transform the 5 volt from the USB port into 4.2 volt.
At least this will be as safe as the fake mains based charger.
Would you mind just giving me a brief summary of why it's hard to get 4.2V of output from a charger circuit that takes 5V input?Milking 4.2V from my design will be a hard nut to crack but I'll try.
Thanks. I will either use solar cells or a AC/mains-to-USB adapter to test, but not a PC.In that case a single 1N4002 would put the charge voltage in range but there would be no over current protection for the USB port. Personally, I hope he decides to used solar cells and not risk PC damage.
It looks pretty cool, but I cannot order it because I am in a place where I cannot easily receive orders like that via mail.If your battery is a single cell type battery the MAX1555 may be usefull. But it is sot23 type package. At sparkfun you can also order this http://www.sparkfun.com/commerce/product_info.php?products_id=726 it may do what you want to do.
by Jake Hertz
by Jake Hertz
by Aaron Carman
by Aaron Carman