Below is a simple charging circuit using LM317 and BC547 and it is mostly classified as a float charger in many forums. This seems to reduce the current flow when the battery is fully charged, however does not turn off the charger completely. Hence can this be connected to SLA batteries indefinitely without affecting the battery life? or is this a trickle charger, which should be disconnected after charging.
By definition float charger will only turn on and charge your battery when it has self-discharged below a certain level, whereas a trickle charger continuously emits a small current of electricity regardless of the charge level or even if it's full. It is also mentioned that for SLA batteries, a float charger could be connected indefinitely where as the trickle chargers needs to be disconnected after charging.
Updated components as per recommendation