How To

Fixing Loose Battery Terminal Connections

Prevent numerous problems by checking and tightening battery terminal connections.

By Kevin Falvey

Updated: March 14, 2014

Battery terminal showing hex nut in lieu of wingnut.

Fixing Loose Battery Terminal Connections

The terminal boots have been slid back to reveal the hex nuts that replaced the standard wingnuts. Kevin Falvey

Loose battery terminal connections create a range of problems. At worst, they can cause overheating and fire. They can also cause poor engine starting and reduce the ability of a battery to be recharged. (We think more than a few complaints about poor alternator performance are a direct result of loose battery terminal connections.)

To help prevent these problems, replace the wing nuts that come with marine batteries with locking nuts. In addition to assuring tight terminals, they make for a cleaner installation. You’ll need either two 5/16 -18 nuts for most newer batteries; other batteries may require a 3/8-16 nut for the positive terminal and 5/16-18 for the negative.

The Case for AGM batteries