What is the size for battery on a 1998 Jeep Wrangler?

The battery size for a 1998 Jeep Wrangler depends on the engine and options. There's no single answer. You need to check the battery itself (it's usually printed on a sticker on top), or consult your owner's manual.

Generally, a 1998 Jeep Wrangler would use a Group 34/78 battery, but it could also be a Group 35. Always verify this information by checking your vehicle or its documentation. Trying to install an incorrectly sized battery could damage your vehicle's electrical system.