Trickle chargers slowly and continually charge the battery, usually overnight taking 12 to 14 hours for a flat battery.
Trickle chargers continue to force charge into the battery even when the battery is fully charged and this will overcharge, overheat and eventually damage the battery.
Overcharging at weekends and holidays is almost impossible to avoid and for radios in heavy use trickle charging is too slow for a midday boost charge. For this reason trickle chargers are no longer used on good quality radios. All good modern radios have intelligent chargers.