RE: Which Charger?
most chargers that charge 8s, have input voltage of at least 30V and the charger boosts the voltage to higher than the 8s.
The less voltage the more the amps,
the supply will only give what is on the output side, 8s5000 is 168Watts with 12V supply that would be 14A+ 25% for losses to charge the 8s lipo at 5A and that supply would be working hard.
If it was 24V supply, the current halves to 7A + 25% to charge at 5A