Be careful, some of the batteries communicate with the laptop through onewire protocol, not an issue for using charger to charge any ole battery. I guess that central pin is easily damaged and shorts out, maybe some of the generic batteries would not take that 3rd wire into account.
I just finished up my Dell 7A 19.5C charger setup on my split back ebike battery. Just found a guy local who is selling them, there are higher amp chargers out there. This is your goto for any info on that
https://www.laptopchargerfactory.com/
they do not sell batteries
But I am sure its easy to build your own.
Sorry I cant be of more help.