80# MK Fortrex ??

[nam6869usmc]

My batteries are showing 26.8 Volts fresh charge when I go out, when I get in the water my GPS top speed is 3.5mph, I do troll on #40(4) at a speed of 1.8mph for about an hour. The rest of the time approx. (5 hours) we just work the shore line for Bass. Now for two straight days I noticed my Fortrex sounds a little weak coming back to the ramp on high & my top speed is only 2.5 mph...when I got home I checked my batteries and they are showing 25volts. I'm loosing 1 mph on 25 volts remaining charge , is this normal??.

P.S. the Fortrex 80 is only 12 months old..