Every battery needs care! It is a myth that a lithium battery requires no maintenance or cannot break. Every battery must be properly recharged regularly, including lead-acid batteries (AGM, Gel) and lithium batteries. To guarantee a long life cycle, a lead-acid battery should never be discharged deeper than 50%. Regularly charging properly (with the right charger) prevents loss of capacity. Voltages below 12V should be avoided. If the lights in your vehicle or vessel are dim, or the heater won’t start, then the battery is truly empty. This causes irreversible damage to traditional lead-acid batteries.
A lithium battery can be your loyal partner for 15 to 20 years, provided you treat it well: A lithium battery must always be protected by a BMS (Battery Management System). Deep discharging the batteries is permitted, as a good BMS will intervene in time, but… There is one condition: after a deep discharge, the battery must be recharged immediately. In a healthy, high-quality lithium battery, the electronics ensure your safety. The components have a continuous minimal power consumption, even if your battery has been preventively shut down by the BMS due to deep discharge. If you leave the battery completely discharged, the minimal self-consumption can cause irreparable damage to the battery after a few weeks!
This is the fate of some batteries left behind in winter storage. A 12V lithium battery that drops below 8 Volts is irrevocably defective. Unfortunately, such batteries are not eligible for warranty.