Well, if you constantly charge a battery that is always outside (cold/heat) - is the charging current right...? - then you can also do without a battery - because then a) you probably won't need the battery and b) the battery will be gone pretty quickly - and buy the wired version of the bell...
And just, with us the bell currents are higher than 24V (we have 90 with additional protective current) - perhaps it is just right with you in terms of current and it charges with 8-24V...
My estimation may be off...

Hello - I can only advise against connecting the battery model to the existing doorbell installation, and there is a "wired" variant that uses the existing installation - it's best to check their website to see what else you might need ...
LG