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Topic: 2s Lipo Charging from USB (Read 2381 times) previous topic - next topic


Hi, Im still new to electronics but learning fast, i hope someone can point me in the right direction on this question!

I am designing a stand alone board that needs to run a small 5v motor. I would like to use a small 2s Lipo pack for this. It will probably be in the range of 140-300mAh capacity.

I would like to install the pack and board inside a Key-fob style enclosure and dont want to have to remove the pack each time to charge it.... Ideally it would just like to use a usb cable to charge from. Either from  an iPhone Charger (5w) or at a pinch a PC (2.5w) but both of these are only 5v. My inexperienced thoughts give me a couple of options...

1    Charge the pack in series. i found this charger controller by Microchip -MCP73213 that i could use... http://www.mouser.com/ds/2/268/22190a-13379.pdf
     The spec gives a minimum supply voltage of 4.2v. is this gunna work or should i use a step up for this?

2    Charge the pack in parallel. Basically use 2 MCP73833 controllers as used on the adafruit chargers and connect them via the Balance leads on the pack.

thanks for any thoughts you may have :D

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