Lithium batteries are light in weight, large in capacity, long in life, fast in charging and maintenance-free, but expensive. Lead-acid battery has mature technology and reliable performance, and its price is much lower than that of lithium battery, that is, speakers with long charging time and heavier power are cheaper than lithium battery.
The plan is affordable, and the battery is cheap.
The picture is convenient to use lithium battery,
The same price must use batteries,
For reference,