I know exactly how much current a GLS10 draws, and it depends on range and depth among many other settings. It isn't static. I really don't like discussing it and my numbers, because in the past there has been negativity directed my way by some because it contradicted published info from "pros". Huh. Measure it yourself, sez I.
I will tell you I am using a 50AH lithium battery (one of many good brands), and a solid 6 hours of fishing today knocked it from 100% to 87%. I have run it 3 trips in a row without charging. In my kayak, I was using a 20 AH, and while it lasts a good long day, I wouldn't push it to 2 days (It charges fast anyway). I use a lithium strictly for weight reduction - the main reason for choosing one.
"Alive without breath, as cold as death; never thirsty, ever drinking, all in mail never clinking."