Has anyone ever tried to bring an old battery back to life? I saw online a few things you can try but was wondering if anyone had tried or had experience trying this. Thank you.

I don’t think it would last. Every battery only has so many discharge and recharge cycles. The way they are maintained extends or decreases that life. A good build in charger that maintains the battery’s pays for its self! It charges them and then maintains then as needed. Nothing worse that finally getting to go fishing after working too much to have a battery fail. Either cranking or trolling motor. Both suck when they fail. I’ve been there. I finally broke down and bought a onboard charger years ago.. worth every penny!

I have not tried it. I did some research and decided to take a pass.

Wear some safety goggles and have some water nearby if you plan on popping the top of the batter to get to the cells.

not worth the effort imo

Sulfation is the formation or deposit of lead sulfate on the surface and in the pores of the active material of the batteries' lead plates. If the sulfation becomes excessive and forms large crystals on the plates, the battery will not operate efficiently and may not work at all. Common causes of battery sulfation are standing a long time in a discharged condition, operating at excessive temperatures, and prolonged under or over charging.

https://www.batteryweb.com/faq#q2