Clean the battery up with baking soda and water then fully charge it. Store it in a cool dry location. Recharge the battery every 2 months.
call an auto parts store.
Remove the battery and have it tested at any auto parts store.
You can get your new jet ski battery on eBay. You can also check amazon.com. Your jet ski battery can also be purchased at an auto parts store or even Wal-Mart.
A good auto battery will hold it's charge for at least 6 months or longer.
Any Auto Parts Store will test your battery for free.
I don't know the exact deminsions of the battery, but you can go to advanced auto, or any auto parts store and they can tell you what size battery you need.....a new battery costs around $50 to $75 with the trade in of your old battery (called a Core)
An ag13 battery can be bought at an auto store. You might also find one at a department store in the auto department. You can alone find one on the Internet.
From your local auto parts store.
Have the battery tested at any auto parts store.
With a hydrometer which you can buy at any auto parts store.
You can test your battery with a battery tester. If you don't have a battery tester, you could take the battery to Advance Auto Parts and they will test it for you for free.
Drop it off at any auto parts store. If you want to get paid for it you can take it to a battery store.