[scrammer]

I feel this distinction should be made.
Here is the reason i use a tender for winter storage!

The difference between a trickle charger and a battery tender is that a trickle charger constantly applies a charge, whether the battery is fully charged or not. A battery tender, on the other hand, has circuitry that monitors the battery and charges only when the voltage has dropped below a preset level, thus preventing overcharging and damage.
When it senses the voltage has dropped, a battery tender will resume charging. Because of this a battery tender can be left connected indefinitely.