SparkFun Forums

[qwertymodo]

I'm looking to build a Li-Po battery pack out of the spare cell phone batteries I have sitting around, using the TI BQ25060 charger IC and the TI TPS61202 boost regulator to get 5V output. The batteries I'm using are from the Galaxy Nexus, which have the 4-pin connection and share a standard size between several phones, including the Galaxy Note II (though the Note's battery is longer, the other dimensions and the connector are the same). I basically just followed the reference schematics for the two chips, but I was hoping somebody might be willing to take a look at my schematic. I included the feedback resistors on the regulator in case I wanted to swap it out for the adjustable version, but right now, my plan is to just take 5V in (mini/micro USB) and put 5V out (USB-A female). Eventually, I'm planning on modeling a case for this, I've been wanting to do some 3-D modeling for awhile, but first I want to make sure I have the schematic right. I'm not sure if the battery has an internal thermistor or not, but I have a pad on the board for an external one anyway.

Potential improvements:
-Switch instead of J1 to select between 500mA and 1A charge rate (or maybe some way to auto-detect a high-current charger, but I'd need to figure out how to do that...).
-Switch to completely disconnect the battery, but 55uA Iq isn't bad.
-ISet pot to adjust charge current.
-???
-PROFIT!!!

Comments/critiques/suggestions? Or maybe does anybody know what the other two battery pins are (NFC antenna and...)?