wrote
I was wanting to use the marine battery I have but someone else posted
a negative experience with the fumes ruining part of their house and
their own health. It scared me a little.

Starting with a new battery, I have used a 12v marine deep-cell with small
float-charger to power a 25w VHF transceiver for over two years. For short
periods, this will handle 100w xmit on an HF rig that draws 20-30amp. When a
charger is connected to a battery, adequate ventilation must be provided,
and the smoking lamp is "out". There is nothing wrong with using an
emergency backup battery as part of normal (indoor) operations. It will
provide hundreds of hours of monitoring and several minutes of low-power
transmit w/o requiring a charge.

Jack Painter
Virginia Beach, Virginia