Battery Question

All,
I purchased an 8 Amp-hour battery for use in my ASW-20 about 6 months
ago. I had been running a radio, ELT, 302/303 combination, and IPAQ
3800. With that combination my battery would last longer than I wanted
to be in the air; generally more than 5 hours.
I recently removed the 303 and added an SN10B with one meter, so the
electric instrumentation suite is now a radio, ELT, SN10 with one
meter, 302 and IPAQ 3800. At first I didn't notice any difference in
battery performance, but lately it seems the battery has been lasting
progressively shorter periods, and this past weekend the SN10 gave me a
low battery warning after only 2 hours in the air, and that was without
arming the ELT. I keep my battery on the charger on float whenever I'm
not flying, which means it stays on the charger all the time except on
weekends, and it's not even a year old.
Does anyone have a sense of whether I am facing a battery that is
failing, a short somewhere, or simply too many instruments on 1
battery? The battery is a PowerSonic 1280, and the charger is a
standard RR14650A gell cell automatic charger. I also don't have the
tech sheets on all the instruments to add up the current drain so I
can't calculate the expected performance from the battery.
Respectfully,