I think we got us a combo deal here.

Can't read the label, but I'm guessing that's a group 27...if so, I'd step up to a 29 or 31, whichever will fit.

Trolling Motor....44 lbs on a 16' decked tracker is fairly marginal. I'm guessing even in moderate winds, you've had to run mid range speeds or higher, which draws higher amps and in turn shortens available run time. If 12V is your only option, I'd go with a Minn Kota Maxxum 55 lb if cable steer or a Terrova 55 if you want to. Both will have the digital maximizer which is a pulse width modulator to extend battery life. Basically, how it works is it cuts the TM on and off hundreds of times a second which translates to about 33% more battery life since it's only actually on about 2/3 of the time. MG's Digital Tours have something similar, but I just don't trust 'em and basically only gewbers run 'em and I don't want you to be a gewber.

Wiring - It looks undersized....from the pic, I'd almost say 10 guage, but it's probably 8. If it's 8, it'll do, but if it's 10, replace it. If it's 8, it's the least of your issues, but still will provide some additional resistance over it's length, if it's 10, it will be a great deal more and it's a hazzard. At 12V with a 44lb TM, it would probably get warm to the touch in wind. If you step up to a 55 lb, it'd prolly get hot...if you jumped to 24V, you'd have a fire hazzard. In any event, I'd look into it a bit more. Won't be easy to replace, not cheap with good wire. You'd be looking at maybe $75 for good Marine tinned 6 guage and if you're lucky 2 to 3 hours of labor...If not, maybe 6 hours. But it is peace of mind. Total off the cuff guess, but with you set up as described and 8 guage, you're probably loosing 5% of your battery.....if it's 10 guage...maybe 15%....again, a guess.

Charger - I see it must be a portable one, but you didn't say what kind/model. I'm dead set against automotive chargers without automatic cut offs and maintainers. I've used a Shoemaker ship and shore with good results, but those little shop ones that are 2/10/whatevers are battery killers. That said, if you were over charging, you'd be having water issues...since you aren't, that probably isn't the case, but thought I'd mention it.

If all of the above does not address your problems, you could always wire 2 batteries for 12V and double your troll time, but here's how I'd prioritize your issues:

1) Wire - if it's 10 gauge, replace immediately.

2) Battery...you obviously need a new one now....go with as good of one (flooded cell) as you can afford....maybe an Interstate or if you're a rich man, a Trojan SC225...which IMO is the best flooded cell out there (about $180)...keeping in mind, if you have to lay in a 2nd battery, you'll need to be able to afford a 2nd one of the same size and brand shortly.

3) Trolling Motor - This is most likely your biggest source of power loss.

4) Charger - If I had to bet, I think you're OK here.

Wannabe...