fairly sure thats in relation to Lithium Ion batteries.
Boats use Lifepo4 batteries. these dont catch fire and burn like the Ion's do.
As for electrics.
Ive owned a motorguide for the past 4 years. its been flawless. 24v on 2 seperate boats. one a 6m hooker and 680 glass boat.
As long as you can see the LED's on its easy to use.
I prefer the motorguide as a cheaper option. parts are easy to replace. Second remote is only $150 and can be linked with a second one.
If all you need it for is spot lock and straight line trolling then you dont need to link it to sounders etc.
buy yourself a cheap lifepo4 80-100AH battery and it will last you days on a 4m tinny