Wouldn't a trickle charger connected to a disconnected battery be a better option to keep it charged up?
That is certainly an option. There can be some confusion and ambiguity between what is a ‘trickle charger’ and a ‘maintenance charger’. And some modern or smart chargers can do both ‘charging’ and ‘maintenance’.
My take (and opinions may vary) is that a ‘trickle charger’ will essentially be a slow or low-current charger, but it will eventually take the battery up to a full charge - and full voltage (usually 14.7V) and hold it there indefinitely. Whereas as ‘maintenance’ changer will back off a bit and hold the voltage at something like 13.5 V. This will hold the battery at a charged state, without sailing too close to the ‘gassing voltage’ which is any thing over 14.7V, but is temperature dependent. So holding a battery 14.7V may lead to it gassing a little and drying out (albeit very slowly). Holding the battery at a lower voltage is better for long term storage.
However, many modern battery chargers will automatically revert to a ‘maintenance mode’ after a period of time, so they are quite suitable for recharging and maintenance of a battery. So it is worthwhile digging out the instruction manual and seeing what ’modes’ the battery chargers has. If it has a ‘maintenance mode’ in the 13.x V region, then I reckon it’s fine (even ideal) for longterm use. However, it it holds the battery at 14.7V (or 14.4V) then it probably better used periodically rather than continuously.
