Those devices have a LiPo battery (nominal voltage 3.7v, 4.2 at full charge), a charging circuit, and a dc-dc boost converter to get 5v out.
You can probably (with some care) remove the DC-DC converter for the output. The catch is - you don't want to bypass the UVLO, otherwise you could overdischarge the batteries.
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Those devices have a LiPo battery (nominal voltage 3.7v, 4.2 at full charge), a charging circuit, and a dc-dc boost converter to get 5v out.
You can probably (with some care) remove the DC-DC converter for the output. The catch is - you don't want to bypass the UVLO, otherwise you could overdischarge the batteries.