Hi,
I´m the person doing reliable stuff. Thus I´d first need specifications and requirements .. then I´d do the math and the verification according datasheets.
So like load current, if pulsed: then peak current, frequency, waveform...
and also whether you want/need to use the same charger, and if yes: what it´s charging method, threshold voltages, currents.. and so on.
Li-Ion batteries are much more critical .. and on mistreatment they may die way too early or even explode and cause fire.
Klaus