Ampere meter can only be connected to 5v input end of the module.
It is better that the charging current is 37% of the battery capacity. If you charge to the battery of 1000mAHcurrent of 400 is enough.
The connection wire should not be too thick.
Make sure the connect point is good.
If the input voltage is too highlike 5.2vthe current will be less than 1000mAit is normal. It is protection functionauto-substract the charging current to avoid burn damage to chip.
NO Reveral polarity.
Size: Small to 25X20X5mm.
Features:
Charge module- Linear charging.
Current- 1A adjustable.
Charge precision- 1.5%.
Input voltage- 4.5V-5.5V.
Full charge voltage- 4.2V.
Led indicator- red is charging Green is full charged.