Guy's you're all making this lead acid thing way too complex.

Just go to Walmart and pick up a Schumacher battery charger, model# 1562A.

It's a cheap and perfect charger to not only charge the lead acid batteries we use at the field, but it's specifically designed to be left on a battery virtually all the time and will keep the battery at it's perfect charged (but NOT overcharged) state.
Not only will it not hurt your battery by leaving it attached, but keeping a lead acid battery at it's optimum full-charged state will allow you to get the maximum life out of it as well. I've got 2 batteries that still load-test like new that are over 3 years old, and they've spent 99.999% of those 3+ years attached to the 1562A's.

I've got four of these chargers, and they are ALL doing full-time duty attached to the several LA batteries in my vintage cars, motorcycle, and of course, RC field battery.

And by the way, the price shown is about twice what you have to pay for it at Walmart, so pick up a couple, hook them up, and just walk away and forget about them until you want to go fly.
I don't think I paid more than $20 for any of mine that I bought at different times.

http://store.schumachermart.com/sem-1562a.html