Suitable for 18650 lithium non-protection board. Three charging current (0.3A, 0.5A, 0.8A) can be set via external resistor; two resistors (0.3A, 0.5A) is current setting resistor;. For example, after removing 0.3A resistor and keeping 0.5A resistor, then the charging current is 0.5A.
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