Using multiple 18A chargers may be more convenient and allow you to charge your batteries in parallel, but using a single 50A charger may be more efficient and allow you to charge your batteries faster. However, it is important to consider the capacity of your generator and the maximum charging rate of your batteries.
Using a generator to charge your batteries can be done, but it is important to use a charger that is compatible with your generator. Non-inverter generators can be prone to voltage fluctuations, and it is important to use a charger that is able to handle these fluctuations and protect your batteries from overcharging or undercharging.
It is also important to consider the charging rate of your batteries. If the charging rate of the 50A charger is too high, it may damage your batteries or shorten their lifespan. On the other hand, if the charging rate of the 18A chargers is too low, it may take a long time to charge your batteries fully.
In summary, using multiple 18A chargers may be more convenient, but using a single 50A charger may be more efficient. It is important to consider the capacity of your generator and the maximum charging rate of your batteries when deciding which option is best for you.