Is the LiPo battery Babysitter meant to charge over USB?

Components & Accessories Power
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I have one of your lipo batterybaby sitter modules connected to a 18650 li-ion battery on the battery input and connected to a Seeed Studio XAIO SAMD21’s Vin pin from the BB’s Vout. The Xaio operates on 3.3v and has a voltage regulator on the Vin pin to accept a range of voltages. When the XIAO is connected to USB-C its Vin pin outputs the input voltage, in this case 5V USB power. My questions are as follows:

1)When I connect the XAIO to USB to program it, the 5V USB power is connected to the Vout pins of the Battery babysitter. This causes the Battery Babysitter to indicate that it is charging the battery, and indeed it does charge the battery, so the Vout of the BB must be bidirectional? I am concerned that it is not regulated properly, however, as the input current differs from when the BB is connected to its own Micro-USB, and it is not affected by the current regulating jumpers on the BB. I do have a separate BMS module installed for the battery. Is this bidirectional/charging function intended? It would actually be very useful if it was as I will be able to use a single USB port for my device. It seems to function fine, actually, but I am worried it is damaging the battery.

  1. Is it acceptable to use the 18650 cell with the BB charging feature in lieu of a LiPo, or will this affect the longevity of the battery?

  2. Is it possible to use the I2C battery monitoring functionality of the BB without using its charging functionality?

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  1. yes, Vout goes to both the system + battery, check out the schematic here https://cdn.sparkfun.com/assets/learn_t … ematic.pdf

  2. it depends on the battery’s specs, but setting the charge rate to 500ma is likely fine…google says most 18650s charge around 1250mA max. The main thing you’d want to check is verifying that the BB is cutting charge when the battery reaches 4.2v (ensure it doesn’t over-charge the battery)…should work as described

  3. https://learn.sparkfun.com/tutorials/ba … management 'TLDR

If only a battery is present, the output should be about the battery voltage (minus a small drop).

If battery and 5V USB are connected, and the battery is charging, the output will be 3.8 - 4.3V.

If battery and 5V USB are connected, and the battery is fully charged, the output will be 4.5 - 5V.’ so…a bit of yes and no

I’d run through that guide and just poke around with a multimeter before/during after changes and make sure it’s performing the way ya want

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Product page:

The SparkFun Battery Babysitter is an all-in-one single-cell Lithium Polymer (LiPo) battery manager. It’s half battery charger, half battery monitor

Yes, it charges over usb.

It sounds like your board is backfeeding into the battery babysiter though and that’s likely not a good idea since you’re bypassing any safeties in the charging portionof the board. A shottkey diode between the two boards would be a good idea to prevent backfeeding.