Simple guidelines for charging lithium batteries Turn off the device or disconnect the charge during charging to allow the current to drop unhindered during saturation. Lithium-ion doesn't need to be fully charged; a partial charge is better. Based on this, a charging voltage range between 13.8 V and 14.7 V is sufficient to charge any battery without causing damage. DO NOT leave the lead-acid charger plugged in to maintain or store the battery, as most will NOT maintain the proper voltage charging algorithm for lithium batteries and the battery will be damaged and this is not covered by the battery warranty.
Stage 2, constant voltage, begins when the voltage reaches the voltage limit (14.7 V for fast-charging SLA batteries, 14.4 V for most others). If you need to store batteries for an extended period of time, you should keep a few things in mind, as the storage requirements are different for lithium and SLA batteries. This means that a 10 Ah lithium battery can normally be charged at 10 A, while a 10 AH lead-acid battery can be charged at 3 A. When you charge or discharge the battery, electrons leave the battery through electrical current and ions flow from one electrode to another.
A charger with a lithium configuration will attempt to recover or “activate” an overdischarged lithium battery that is in protection mode. If you've recently purchased lithium iron phosphate batteries (referred to as lithium or LiFePO4 in this blog), you'll know that they offer more cycles, an even distribution of energy supply, and weigh less than a comparable sealed lead-acid (SLA) battery. It is very common for lithium batteries to be placed in applications where an SLA battery used to be maintained on a floating charge, such as a UPS system. In this charging phase, the charger will maintain the maximum voltage for the chosen battery and will charge it with a reduced current, since the internal resistance of the battery cannot accept the charging current at the maximum output.
The charging of the battery in stage 1 is normally carried out with a current of 30 to 100% (from 0.3 °C to 1 °C) of the nominal capacity of the battery. It's always important to adjust the charger to provide the correct current and voltage for the battery you're charging. The full-charged open circuit voltage (OCV) of a 12 V SLA battery is nominally 13.1 and the full-charged OCV of a 12 V lithium battery is around 13.6.A lithium battery can be charged at a rate of up to 1°C, while a lead-acid battery must be kept below 0.3°C.