I bought two of the Dakota Lithium battery 12 volt 10 amp so when one ran down while on the water I could keep on fishing. The original still last about 6 hours but the newer one only last about 3 hours now. I have used them a lot over the last year but I honestly don't see a benefit over my old lead batteries other than weight. Lifespan wise I'm getting a year's worth from lead and the lithium batteries. I am interested in Nimrod's and Super Dave's new batteries though. The 40 cost less than the 42 so I'm real curious how they compare. I really like the lightweight of the lithium battery and if it 40 & 42 holds up for them I 'll probably buy one as well.