Recently purchased a Xtar VC4S from Amazon as my trusty VC2 was getting a bit long in the tooth and I had a lot of 18650’s I wanted to drop down to storage voltage.
However out of my stock of batteries, 7 have now died after charging them in the VC4S. Some of my older Efests that were charging fine in the VC2 just died instantly when I put them in the VC4S (voltage dropped to zero, never came back), whilst 2 Samsung 30Q’s got really hot whilst charging, made a pop sound and stopped charging (batteries were so hot I had to throw them out of my study onto the lawn for safety).
Is this a bad charger or a case of batteries which were close to dying already and just failed because I charged them?
They might be old cells. I have the vc4s and I have no problems so far. My usb adapter has both quick charge 3.0 and regular usb output ports. I use quick charge 3.0 when i charge 2 or 4 new cells but if I’m charging older ones, i just use regular usb output to lower the charging current.
Mainly older cells, the 30Q’s weren’t terribly old and hadn’t been used much though. Still somewhat concerning that had I not had a USB fan pointed somewhat at the direction of the charger the battery would likely have caught fire.
It sounds like your charger has an internal short circuit that is draining the batteries down, that could be very dangerous if one vents. Is it a genuine XTAR and not one of the many knock offs? I would return it if possible, and definitely stop using it!