[johno]

+1

[Ducati Scotty]

Most flooded lead acid motorcycle batteries come with a container of acid.  Either the liquid acid is in a multi-pod packet that you cut the tops off and it fits right into the fill holes to dispense, or the acid is in one big container with a fill hose and you fill each cell individually.  A bit of a hassle but easy enough to deal with if needed.  Either way, once you've filled it you need to give the battery a full charge.

Both gel and AGM are still lead acid batteries with the same basic technology.  They can be a bit more powerful and less prone to self discharge.  Their main advantage is a sealed or semi-sealed battery that does not need to be inspected or topped up and can be mounted in various orientations without dribbling acid all over the place.  For some late model bikes that mount the battery on its side these are the only options.  They are also both less prone to be damaged over time by vibration, an important consideration for motorcycles.

Gel and AGM will last longer and are probably worth the extra cost.  Lead acid works acceptably in most cases and is cheap.  If you ever have one overflow, spill or overcharge, and puke acid all over your bike you'll probably never look for that kind of bargain again.

Scott

[suitcasejefferson]

Hey you liquid acid battery fans, what are you thinking? LEAD acid flooded batteries WILL CORRODE your hard earned machine, nearby electrical contacts, & possibly PUKE ACID & RUIN YOUR CHROME EXHAUST SYSTEM. The sealed AGMs are the same size your bike requires, have more cranking power & last twice as long if you pad them with foam rubber. They cost up to twice as much as a flooded battery, & worth every cent ! - many have a year warrantee. 
HARBOR FREIGHT TOOLS sells a float charger for $13. that is compatible with AGM batteries, & is fine applied overnight every few weeks.
  I encourage you to take advantage of a good thing. After owning an AGM you couldn't pay me to go back.

You are 100% correct. I have a battery acid catch tank connected to my vent hose to prevent those issues. Been using them for 30 years, back before sealed batteries became available, and never had any real problems. I'm watching for any sign of problems. I will be getting an AGM battery when the oem one dies, because of how hard it is to maintain.

As for the charger, I have a 1 amp CHARGER that works with any lead acid battery including SLA, AGM and gel types. I also have several "battery tenders" (one for each bike) that work with all lead acid battery types. These are not chargers, and will not charge a dead battery. They are "maintainers" I leave them connected to the battery at all times when the bike is not being ridden. They sense the state of charge, and maintain it. They are not charging all the time, and will not harm any lead acid battery when left connected indefinitely. Mine are Battery Tender Jr.s, made by Deltran. My batteries have started lasting a lot longer since I started using them several years ago.