I am getting into my first project and have a questions about LiIon batteries. So much information out there and confusing and I am not sure if I am overthinking or what the easiest/best value solution is.

-I want to run a 5v Arduino and 5v 300mA micro air pump from a 1S2P 18650 battery pack. I assume I will step up the Lion voltage to meet these loads. -I want to be able to charge the battery pack via standard MicroUSB input -I will use two new batteries, initially charged to same voltage, so won't need to balance -I want to be able to charge and use the device at the same time

What I understand/Where I am confused:

There are two USB charging chips on boards out there: MCP73833 or TP4056 I don't really get what the difference is, or why I would choose one over the other.

MCP73833 boards like this are relatively expensive, but have easy JST ports to work with. https://www.adafruit.com/product/259

TP4056 boards come in old and new flavours, apparently the new version can charge and load at the same time, the old kind cannot. How do I tell which is which from everything out there??? Can this one?: http://www.ebay.com/itm/112057059077

There are battery packs out there pre-made that have PCB built into them. Can I charge those with one of those MCP or TP boards, Or does multiple protection circuitry confuse itself?

Same question for battery holders that have PCB's built in.

ie. Does the built in protection circuitry make an issue for the Charging modules?

TLDR; Just trying to find the easiest way to charge and use a 1S2P battery at the same time

Thanks for any insight!

  • \$\begingroup\$ The PCBs on those lithium ion cells are protection from overvoltage, overcurrent, and undervoltage. They are not charger ICs. \$\endgroup\$ – Joel Wigton Oct 25 '17 at 21:14
  • \$\begingroup\$ @BigBrosMo I have almost the exact same questions, did you find by any change some answers? Thank you \$\endgroup\$ – bob Sep 1 '18 at 9:36

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