The electric winch handle batteries have great autonomy, enough to sail a day without a problem.
 
Example of use on a 40 feet sailboat with a 15 knots wind:
Hoist 3 times the main sail
Tack 30 times
Charging time: 1 hr. 30 min. (12V and 220V)
 
For sailboats bigger than 45 feet, we recommend having a spare battery.
 
*If buying a new battery for a previously purchased eWincher, make sure to check that the voltage on your unit matches the batteries being sold. 25.2V units are not compatible with 28.8V batteries.