I have used the Deltran tenders for about 6 years, and I've had no battery run downs or problems since. This is a first for me hearing about a catastrophe with one of them. Mine is left on 24-7 as well.
'02 CAMARO SS SOM; 5.7L LS1/FLS6B
'08 TBSS AWD Black Granite Metallic
'15 Malibu LTZ 2LZ Turbo
'14 CAMARO ZL1 Blue Ray Metallic