I let my old large screen Eagle go with a canoe I sold. I planned on getting a smaller new lighter weight lower power detector.  I purchased a humming bird that was the store demo unit.  I do not know if the problems are because as a demo unit it ran for weeks with the transducer out of the water or if the unit just does not do well.  It loses the bottom all the time and if it is run in auto sensitivity it can’t find the bottom. If the sensitivity is high enough to see the thermal it thinks it is the bottom.  It is lighter and uses less power.  So don’t buy a demo unit.
As far as batteries go the lithium are still a good choice.  There is a rechargeable that is an equal as far as weight and will run your detector as long on a full charge. Here is a link to info on something I am going to try this year.
  (You need to Login or Register
I am doing some testing on a Hook-4 detector.  Looks like the above battery setups will run the unit for 11 to 15 hours. It draws a little more than 2 times as much as the hummingbird. It is heavy with a lot of the weight in a 30 ft transducer cable.