I use real power supply (13.8v output, 10A).
When is connected to 12v field battery it’s getting hot also.
I charged my old batteries and new ones (1400ma Rx and 600ma Tx). Nothing is wrong with them. Actually the charger is getting hot for couple years and never gave me any problems yet, maybe it’s getting hotter than it use to.
My planes become more and more expensive and I'm just trying to be cautious not to crush $2K plane because of $50 charger.