We talk of trickle chargers verses float/maintainer chargers,.......
In reality, I don't believe you can buy any small 1-2 amp trickle charger that is not a maintainer/float charger,....one that is not designed to leave on a battery all the time,....nor has any been on the market in at least 10 yrs.
If you are not sure of your older charger, trickle or float, just check the finish voltage,....it must not exceed 13.2-4 maximum (in warmer weather) If it exceeds this voltage, it is not a maintainer/float charger, and should not be left connected for more than 24 hrs, or it will cause gassing, and will loose water rapidly.
Note:
in cold weather, a float voltage of 14 and more can be used w/o gassing.
That is why in a perfect world, all of our chargers would be temperature regulated, making for very expensive chargers.
A lead acid battery should be charged every 30 days, or left on a float charger.... if you want the longest life out of it (no matter what Bill thinks)