From consumer reports:

The longest-lived batteries lasted nine times as long as those that failed early.

Sears' Diehard batteries lived up to their promise in our tests, consistently providing long life across sizes. Shortest-lived: the size-35 Champion and Duralast Gold models, despite Champion's long total coverage and Duralast's compelling ads.

The Optima Red Top 34/78-1050 was another long-lived battery. As we found in a previous battery test, Optimas use a spiral-wound cell design said to provide longer life than conventional cells. But at $140, this model costs roughly twice as much as most.

Larger batteries tended to outlast smaller ones in our tests. But because batteries are sized for different vehicles, choices are limited to those that fit what you drive--a key reason our life-test and other scores are relative to others within group sizes.

RECOMMENDATIONS

Our life-test results should make choosing a battery easier, but they aren't the whole story. Check the battery group size and CCA for your vehicle, usually found in your owner's manual or a battery catalog at the store (see How to read a battery). Then choose a battery that scored well overall.

Among group size 75 batteries, the Diehard WeatherHandler (South) 30375, $60, combines lots of reserve capacity with the highest overall life-test score. Also worth considering, and available nationwide, is the NAPA The Legend 75 Professional Line 7575, $60, which scored lower in our life test but higher for CCA and reserve capacity.

Among group size 65 batteries, we recommend the Diehard Gold (South) 33165, $80, for warm climates and the Exide Nascar Select 65-84N, $90, for other parts of the country. While both provide superb CCA performance, the Exide is sold in the cold-weather areas, where cranking power is most needed.

Few of the smallest, group size 35 batteries did well in our life test. But the top-rated Diehard WeatherHandler (South) 30335, $60, and Exide Nascar Select 35-84N, $80, offer a good balance of life-test and other performance.

Among the two group size 34 Sears models, the Diehard WeatherHandler (North) 30034, $60, did well in all three key performance areas. Southern buyers can get similar overall performance with a top-scoring size 34/78 battery, which will fit the same vehicles.

The group size 34/78 Optima Red Top 34/78-1050, $140, was among the longest-lasting batteries in our tests. But the top-rated Motorcraft Test Tough Max BXT-3478, $80, and high-rated Duralast Gold (North) 34DT-DGN, $75, lasted nearly as long and delivered more reserve capacity for far less money.


Don't but more CCA than you need, be sure it has a long warranty with hopefully free replacement, and check to see if you can recharge the old battery first before throwing it out.

T-X