[Gasoline Fumes]

My deep-cycle marine/RV battery (85 Ah) is getting weak at 3.5 years old. I can't drive without the alternator or EOC at night anymore. I've gotten much longer life from batteries in this and other vehicles. I'm wondering if I shortened the life of this battery. When I first got it, I wasn't grid-charging it and it got pretty dead a few times. Then I started charging it with various (low-power) unregulated power supplies that likely overcharged it. I had it up to 15v fairly often with a faint hissing sound coming from it. I'm hoping to make the replacement battery last a bit longer by using a proper charger. Ideally one with at least two charge rates, one for faster charging when necessary and one for trickle charging when there's time.

I also have a small solar panel connected at all times, but that does hardly anything.