For those not familiar with the Lithium type batteries, these batteries are a different animal than lead-acid types.
In daily use, you won't notice a difference except for 1/3rd the weight of lead-acid type, but with higher cranking amps.
But, if the battery is discharged to 11V (effectively dead state), immediately recharge the battery soon as possible.
And NEVER fully discharge the battery. That will destroy the chemistry and turn it into a expensive paper weight.
Not sure about the brand battery you use, but I use a Shorai lithium battery (extremely well pleased) in all my bikes for years.
They provide a charger that plugs into the special connector on the battery, which performs cell equalization and charging.
Others may likewise offer their charger variant.
One can use a regular charger if the battery is dead, but do not connect a trickle-charger to a lithium battery. There's really no need.
If there is no power tap (clock, immobilizer, current leak, etc.), these batteries hold a charge a long, long time and charge up very quickly.
And if sitting on a shelf, they have practically infinite shelf life.
I've had one in a box for 13 years and it has lost only .03V in that time. From 13.5 to 13.47V.