[Mr V]

Do not use a trickle charger and leave it connected for long periods of time. Trickle charger is just a fancy name for a low powered, manual charger that will overcharge the battery and significantly shorten it's life if left connected continuously.

The best plan it to use a high quality charger/maintainer. They will charge at ~14.2v until it senses the battery is fully charged and then either switch off, monitor battery SOC and then switch back on as needed or switch to float mode of 13.6~13.8v which will prevent the battery from discharging w/o actually causing it to charge.

Other tips to maximize battery life.

1. Recharge as soon as practical after discharging.
2. Do not excessively discharge the battery, Discharging below an open circuit voltage of 11.0v shortens battery life significantly. Preferred is to not allow the open circuit voltage to drop below 12.0v. Note open circuit voltage is best measured after the battery has been left to rest for 24hrs without being subject to either a charge or discharge.

In the absence of a charger/maintainer, float charger or battery tender the best plan of action is to charge the battery, disconnect it and after it has sat for a month or so subject it to a bit of a draw and then recharge.