Battery charging

Welcome to the forum Poptart,

It depends...

Li Ion cells are very sensitive to over/under voltage limits. And many (most?) folks use a BMS (battery management system) to both monitor (and some BMS will balance cells) the voltage per cell/parallel ground of cells for over/under voltage... Some BMS also monitor for temperature, current, and can either/both signal the charging source (and loads such as AC inverters) the state of the batteries, and even (more or less) as a last resort kill the electrical connection to the battery bank (to stop over charging, over discharging, over current, charging in near freezing and below temperatures, etc.).

Li Ion batteries are not cheap... And while the common "home power" batteries are LiFePO4 (lithium iron phosphate) (and related) Li Ion batteries are pretty safe (they will not/should not catch fire if mistreated)--They still can be ruined with improper operation. Some other solutions/battery packs use other chemistries that are no so "fire safe" (E-Cars and E-Buses are in the news for spontaneous combustion incidents--And Li Ion batteries that are in a fire can create/release some very toxic substances that can create a cleanup nightmare).

In the end, there is no "generic answer". You can purchase batteries that have integrated BMS systems that will do just about anything needed to keep the cells in a safe operational range (some can even include electric heating strips to keep batteries warm)--And those can be charged with an off the shelf "lead acid" battery charger. And there are battery banks/designs that you should never use anything but a charger designed for Li Ion charging.

Example of a Li Ion battery with integrated BMS:

https://www.solar-electric.com/lib/wind-sun/Discover-AES-Lithium-44-24-2800-42-48-6650-Manual.pdf
https://www.solar-electric.com/discover-energy-aes-2-8kwhr-24vdc-lithium-ion-battery.html (more info, documents)

Remember that Flooded Cell Lead Acid Deep Cycle (FLA) batteries are pretty forgiving with over charging, over discharging, charging in sub freezing conditions, etc... And many "cheap" Lead Acid Battery chargers are nearly "unregulated" and can supply very high charging voltages if left connected (I have measured something like 17+ volts in a "simple" transformer+diode based charger).

High quality Li Ion batteries are not cheap. Integrated BMS will add costs. Chargers/AC inverters/etc. designed to integrate with Li Ion batteries tend to be more expensive...

Highly suggest you go through your loads and figure out how much power (Watts) and energy (Watt*Hours) you need--Do as much conservation as you can (LED vs filament lamps, laptop computer vs desk top computer)--As conservation is almost always cheaper than building a "bigger" solar power system. Once you size the system (on paper), you can then see what out there will meet your $$$ and electrical requirements. You want to do the planning/design first, before you buy hardware and start connecting the bits and pieces together.

Details matter here.

-Bill