bad gut feeliing about my boat batteries...

Having let the boat sit for over a year+ ..
When I charge the batts using the onboard charger, even after getting a green led then three, four days later, start charging again, almost full bank of red leds, takes all night to go green again.

Interstate batteries, 4 years old.

Motor starts fine, spins fast. still.. kinds tough to spend another 200 on batteries dang it.
But with a trip planned, better safe than sorry?
anyone seen this charging behavior ? I have to admit I kinda know its not right.

try topping them off with a standard charger, then let them sit overnight , then hook the onboard charger to them and see if anything changes. i would also top off the water in them after using the standard charger.

btw i’m no expert on batteries but in 9 years of boat ownership i have had pretty good LUCK with batteries. now catching fish is another story......

I wouldn't expect them to be good, about 3 to 4 year's is it for an average batter and letting them sit is hard on them.

My thoughts are buy fresh batteries at the store, by as ”cheap" as you can and replace often... 3 to 4 year's

Go to Harbor Freight and pick up a resistive load tester for around $12. Charge your batteries for 24 hours, let rest for 24 hours, then load test. If the needle doesn't stay in the green, you have a bad battery, probably a weak cell drawing down the others.
You can do better than Interstate batteries.

New Battery time

there is a reason most marine batteries have a 1 yr warranty

how's the water level in the batteries? dry cell will make the battery not charge.

For what it's worth, I manage to get pretty good use out of my batteries after following advice I got here on TFF years ago.

Like most of you I have an on-board charger, but rather than plugging it straight into a wall outlet, I have it plugged into a garden timer that only comes on for 1.5 hours each day. I was eating through batteries pretty quickly even when they were connected to a nice Dual Pro charger that supposedly dropped the charge to nil when the batteries were topped off. I got 6 years out of my last set of Interstate greenies using the 1.5 hour a day charge cycle time.

thanks for replies!
Battery's held up fine thus weekend... but I am pretty sure carbs are needed some love.. would bog and quit trying to hit 2500-3K rpm.
Changed fuel line, its fresh gas, but I suppose there is too much internal build up of gunk.
I have zero boat fixing money too, lol.

get a small gas can and dump a can of seafoam in a gallon of gas and hook the fuel line directly to the can. run on muffs. could possibly help and won’t hurt any worse than it is.

fyi: add oil to gas too if you premix

SEA FOAM!!!

STABIL!!!