By "battery maintainer" do you mean a trickle charger, or a battery tender? Battery tenders monitor the charge cycle to avoid over-charging the battery; that cooking sound is bubbles forming, some of which is normal but a high charging rate will boil-off the electrolyte and ultimately damage the battery. One way of keeping a battery topped-up is to hook up the trickle charger to the garage door opener; it'll get a 3 to 5 minute charge every time you open the door.
I'm not clear from your description whether topping up the cells cured the problems, or not. If a battery is allowed to get too low on electrolyte it may not recover fully, so you might be in the new battery market. A sealed no-maintenance battery would be a good investment in that case, my 2000 Ural and 2002 HD both have them, they're both several years old, and neither has a problem.
"Hard to start" and battery voltage may not be the same thing, either. Mine starts fine, one kick, pretty much regardless of battery condition.
Try this. Buy a volt meter; you can get something that'll work good enough for less than $20. Check your battery voltage without charging the battery, after sitting for a while. If it's much less than about 12 1/2 volts, you'll be buying a battery one of these days.
Also, check the voltage across the battery terminals with the engine running. If it doesn't rise much above 14 volts, it's not charging. I doubt you're over-charging from the alternator, or you'd be popping bulbs.