SparkFun Electronics Forum

Hey guys,

I am trying to decide between two products. The micro usb lipo charger https://www.sparkfun.com/products/10217, or the micro usb breakout board https://www.sparkfun.com/products/12035.

I know that the lipo charger has an IC built in to protect the battery and limit current, but isn't that the point of the protection circuit built into the lipo battery? If I take a 5V micro usb input, and want to charge it to 4.2V at 100 mA, for example, can't I just put in an 8 ohm resistor in series with the battery and let the protection circuit worry about the rest?

-Greg

secretempire1 wrote:I know that the lipo charger has an IC built in to protect the battery and limit current, but isn't that the point of the protection circuit built into the lipo battery?

The protection IC built into the battery is really designed to stop anything really nasty happening - it's not designed to ensure the battery is charged in an optimal manner (that's the job of the charger IC).

secretempire1 wrote:If I take a 5V micro usb input, and want to charge it to 4.2V at 100 mA, for example, can't I just put in an 8 ohm resistor in series with the battery and let the protection circuit worry about the rest?

No - the protection IC should stop a fire or similar, but isn't designed to precisely regulate the battery voltage.

Oh okay, thank you.