yes, and this was my initial thought. Nor the plugs are long enough to touch the chassis nor the plugs touch the upperdeck. Especially, the later set had a plastic case on the plugs!

I'm only thinking that the batteries (as the only suspect or lack of any other?!) have an issue internally on both the internal female slots that might cause the arcing and hence the extreme heat, BUT all three batteries??? If this is the case, way too bad quality

If this is the case, is there any warranty?