I just soldered some brass screws on mine.
This is the battery I use. They are cheap,
seem to last a long time, and are sealed.
Some searching may find them even
cheaper.
https://www.ebay.com/itm/UPG-6V-4AH-Sea … SwoudW9YxJ
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.