I've done a lot of portable operating with a 4.5Ah lead gel battery and a Ten-Tec Argonaut 505 that
draws about 1A on CW transmit. The battery was normally good for about 5 days to a week of
backpacking with intermittent operation in the evenings, or 24 hours of more focused operation.
But I'm not a very serious operator, either: a 7Ah battery would be better for something like
Field Day, and even that might not be enough, depending on how much time you spend cooking
and sleeping. (It isn't uncommon to hear chirpy signals from battery-powered QRP stations
on Sunday.)
For me, 4.5Ah was available, and was small and light enough to work in a backpack. It wouldn't
be the best choice for everyone else, especially as battery technology has advanced since that
time. I'm presenting these numbers as a rough guide for how much operating time to expect
from a particular battery capacity - that will also depend on how much current your rig draws
on receive.
Lithium is probably the best choice for power density, but is more expensive. For frequent long
treks, that would be the best choice. But for shorter or less-frequent trips, and if cost is an
issue, there are other alternatives. 1A is a bit much for Alkaline batteries, but at lower power
levels a set of disposable AA batteries from Costco might not be a bad choice, especially if
you arrange to use the same cells in your flashlights, GPS, and any other electronic devices.
One advantage of designing your system for AA batteries is that you can use NiMh rechargeables,
alkalines, or Lithium camera batteries in it depending on your needs for each trip.
For non-backpacking applications where weight isn't the highest priority, a 7Ah gel battery is very
common and should provide operation for most of a day or so (again, depending on your radio and
your operating style.) For Field Day where I can drive to the site I use some 33Ah gel batteries that
cost me $5 each (used), and easily power the rig for the full time even at 2A draw. (But could be
marginal in a multi-operator group - by myself I rarely operate for more than about 12 hours.)
So careful consideration of your planned operating times and conditions is as important as the current
draw of your radio on both transmit and receive in choosing a battery type and size.