battery help

[id10t]

Running a 12v trolling motor off a 12v deep cycle marine battery (100ah rated) but having some confidence issues and lack of trust with it and my cheap ampmeter "gas gauge"

When my charger says "done" my ampmeter will show 86% charged with no load, as soon as I put the motor on full power the ampmeter shows 40-45%, dropping thrust to 3/5 will bring it up by 20% or so ...

The ampmeter will drop from 36% to 0 and stay there, motor still going but at reduced power level, but not a lot reduced.

Math says I should get just under 3 jours run time... but a hour before ampmeter shows empty and power obviously drops

So ... better way to monitor battery charge? im guessing I need a mariene/saltwater rated ampmeter ... or somethibg else?

Any ideas as to why a full charge isnt? Or why I am getting about half the expected run time? Battery is less than 2 years old

[pwd72s]

Pretty obvious that either the battery or the charger is at fault...I don't suspect the ammeter, because they're a simple device. Batteries Plus store should be able to tes6t for you. 100 AH isn't a lot of juice storage...

[Cajundaddy]

Sounds like the battery has diminished capacity, possibly from running dead flat several times. Hook it up to a smart charger like NOCO or CTEK overnight and they *may be able to restore full capacity.

Time for a lithium trolling battery?? 300Ah with 100% useable capacity for $399 and no maintenance required. Probably good for 5000 days on the water with no muss, no fuss. Does require a smart charger/maintainer with lithium charge profile.

https://a.co/d/0em29pOl

[vash]

lead acid, huh? my brothers batteries give up at 50%.

I have a Dakota Lithium that goes until the bitter end. I did 2.5 days and still didnt find zero.