Assistance Needed on A Very Space Sensitive Project

Other Hardware General Electronics
1

I have a project that I'm trying to develop here [Help Wanted] The ArduWatch - A Simple, Low Cost, Take Anywhere Platform - Product Design - Arduino Forum
and i have ran into a problem.
How do i power the creation?

Then i found these The world's lightest rechargeable battery, lithium polymer 3.7V 450mg, tiny batteries
and i thought my problems were solved, but oh no they were not

Though these seem like a viable power source, how do I charge them.

There's a datasheet for only one of the batteries, but I would prefer to use the one rated at 50MaH

Is there a circuit that I could build that would accept a range of power sources (a 5v USB port, a 9v battery, a 12v solar panel) that would all funnel down these into a usable and very accurate charging source for the battery, auto cut off etc.

As you probably know LiPo's arent very tolerant to energy fluctuations as they could basically explode.
The circuit has to be as small as it can possibly be as well. I could add a port to allow the battery to be charged from a single, non-fluctuating power source (ie 5v .5 amp) if that helped, but the whole point of this project was to make a fully usable, extremely flexible tool. The more flexible the power options, the more flexible the tool.

Anyone know of a prebuilt circuit on the market? What about designs to one I could solder up? This area is not my expertise and I really don't know where to start.

[Edit]
I found these on the website at Battery chargers for lithium ion coin cells The PST-LCA looks like the correct device to charge as they are recommended, but much too big.
I could possibly do a little reverse engineering if need-be

2

There are LiPo charger chips available from many places. I'd use a micro-USB jack for charging.

Here's one pre-built for $9.95. Just cut off the cable connector and wire it to your LiPo cell.

http://www.karlssonrobotics.com/cart/lipo-charger-basic-micro-usb/

(If you are designing your own PCB you can borrow from their schematics.)

3

Thank you, the problem is there is no datasheet I can find on the 50MaH battery. Will 500ma (i'm not familiar with how batteries charge) be okay on such a small LiP?
I'll have to modify the files as it seems a little long for the space. I'll remove the USB port and just solder the lines to the FTX board.

Second question, I need to know if I should really invest the $130 on parts for this project. They're all single order so the expense is increased quite a bit. Is there somewhere that I can get review on my project, the product part of the forum hasn't proved very helpful. Would you ever be interested in something like this? Is it something that could be marketed?

4

You should charge this at 100-200 mAh not more. ANd BTW HobbyKing sell this for $2http://hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=7565

5

Oh my god, THANK YOU. I would've spent $20+ on it... ugh

[Edit] Damn... all outta stock. They don't even list the voltage, any way to tell. I'm sure it's the same, just want to know for absolute.