Battery question for fish finder/electric start

[Rodster14]

I am looking to shed some weight in my 16 ft Riverhawk Pro-Caster. The itself boat weighs only 220 lbs. I now have about 150 lbs of batteries. I have two group 27 batteries that power my Minn Kota 80 lb Terrova. When I upgraded to a new Humminbird Helix 10 Mega SI , I added a group 24 (46 lbs) instead of the small tractor battery I had always used. I feel like the group 24 is too heavy and overkill just to run a fish finder and crank my 20 HP Tohatsu motor. From my reasearch, it appears that a battery like the one below (12 lbs) would work. Would it?
https://www.amazon.com/gp/product/B0...k_ql_qh_dp_hza

[Fishfreq]

It might. It might not, depends on how you use it, if you're running other accessories like livewells, phone and GoPro charging, playing music on your stereo...? If it doesn't, then you'll be pull-starting those 20 ponies. Or you could bring a jumper cable if you can't crank, jump from one of your t/m batteries? Most high power sonar like high voltage and plenty of amps for best performance, so I'd always recommend a little too much battery then too little.

Since you didn't say if there were any budget limitations, you may try a feather-weight Lithium battery like for motorcycles: a 360 CCA 12 cell AntiGravity battery only weighs 2 lbs and cost $200. I've used 'em on motorcycles and they work fantastic. I didn't research if this is enough MCA's for you and reserve for that Helix - that's up to you. They do make bigger ones, but here's the 360:

https://www.amazon.com/Antigravity-B.../dp/B008R0L3Z6

If you REALLY want to shed weight, you could research a pair of 12v Lithium trolling motor batteries, probably could shed more than 100 lbs of those old lead-acid batteries. Keep in mind that Lithium cells need a charger designed specifically for lithium. You'll have to upgrade or else risk damaging that Lithium.

[Rodster14]

I am thinking about the following battery. It only weighs 31 pounds. It is also a couple inches shotfer which would make it easier to take off and on wires when I convert to all electric. I like the idea of lithium, but I can’t stomach the price. Would the Optima Red Top 25 be a reasonable compromise?

• SPECIFICATIONS
  
  
  

  • BCI Group Size:	25
    Cold Cranking Amperage:	720 A
    Cranking Amperage:	910 A
    Negative Terminal Location:	Top Right
    Positive Terminal Location:	Top Left
    Reserve Capacity:	90 min
    Terminal Type:	Top Mount
    Voltage:	12 VDC