Noco Genius 2D Guide D'utilisation Et Garantie page 6

7.) A marine (boat) battery must be removed and charged on shore. To charge it on board requires equipment specially designed for marine use.
Begin Charging.
1.) Verify the voltage and chemistry of the battery.
2.) Confirm that you have connected the eyelet terminal connectors properly and the AC power plug is plugged into an electrical outlet.
3.) All LEDs will flash momentarily, then the charger will begin charging without user intervention.
4.) The charger can now be left connected to the battery at all times to provide maintenance charging.
Understanding Charge LEDs.
The charger has one (1) Charge LED. This Charge LED indicates the connected battery(s) state-of-charge (SOC). See the explanation below:
LED
Pulsing Red LED
Solid Green LED
Pulsing Green LED
Explanation
The Red Charge LED will slowly pulse "on" and "off" when the battery is less than 75% fully charged.
When the battery is 100% charged, the Charge LED will be solid green.
The Green Charge LED will slowly pulse "on" and "off" when the battery is between 75% and 100% charged and during
battery optimization charging. It is normal for optimization charging to occur on a regular basis after the battery is fully
charged.