Boat is an '02 Nitro.

Long story short, the Crews 2611 dual-bank battery charger had a meltdown. This charger is for the dual 12v trolling motor batteries.

The side of the charger that melted also has a bad battery (Interstate Mega-Force, 16 months old) with a dead cell. I  had the battery checked after the charger failure.

I am wondering if the faulty charger damaged the battery, or a bad battery damaged the charger?

Anyone experience this?

Having been a factory repair guy on fork truck chargers....the battery should not damage a charger. You can take the two battery leads and clip them together (without the batts connected) and the only thing that would happen is the output PROTECTION fuse will open.

Sounds like an internal component gradually failed, drawing higher and higher currents. The heat built up to a damaging point before the input fuse reached it's max current.

I agree. complain to the charger manufacturer and get a replacement if under warranty. It should not be possible for a battery to damage a charger if the charger is designed correctly.