EDIT: There appears to be a design flaw in the Xtar VP2 manufactured as of March 2022 that causes it to overcharge LiFePo4 (LFP) cells when then the proper 3.2V charge mode is set. See posts:
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I have an Xtar VP2 with the switch set to 3.2V (for charging LiFePo4 chemistries). It turns green at 3.5 volts as I would expect, with the charging animation stopped. But I recently left a pair of batteries green on the charger for a day and they read 4.2 volts when I took them off!
Now, clearly I shouldn’t leave cells on, but I expected the charger to stop charging once the battery is at selected voltage. Is this by design? Defective? Does the selector switch just control when the light turns green, but the charger goes right on dumping current into the battery?
This excellent review of the charger seems to show that this shouldn’t be happening, stating “Again the charge does a nice CC/CV and turns off when the battery is full.” Test/Review of Charger Xtar VP2
I am certain this wasn’t a charge selection mistake, because I was able to reproduce the overcharge, stopping when the cell reached 3.7.