What is the Difference Between a Group 24 and Group 34 Battery?

Group 24 and Group 34 batteries are two of the most common and popular sizes for batteries in marine and RV applications, including boats, motorhomes and travel trailers. However, there are several differences between the two batteries, which we cover in the video below. One consideration we didn't mention is warranty coverage.

OPTIMA BLUETOP batteries come with an easy-to-understand, two-year free-replacement warranty. Other Group 24 batteries may come with warranties as short as one-year (like the battery in the video) or may have a pro-rated warranty, that requires you to pay for a percentage of your warranty replacement.

As indicated in the video, the dimensions of Group 24 and Group 34 batteries are similar. The Group 24 battery typically measures about 11 inches long, by 6.875 inches wide, by 9.5 inches tall, while the OPTIMA D34M BLUETOP (and the 34M BLUETOP) measures about 10.06 inches long, by 6.88 inches wide by 7.94 inches tall. As the D34M BLUETOP is a bit smaller than a group 24 battery, it should be no surprise that it also weighs slightly less at about 43.5 pounds to the Group 24's 46.3 pounds.

In terms of battery specifications, the Group 24 battery in this video is rated at 550 cold cranking amps or 690 cranking amps (marine cranking amps are the same as cranking amps), while the OPTIMA BLUETOP D34M is rated at 750 cold cranking amps (870 MCA). In load testing we performed on these two new, fully-charged batteries, the Group 24 battery measured 698 CCA, while the Group 34 BLUETOP measured 897.

The reserve capacity rating on the Group 34 BLUETOP is 120 minutes, while the Group 24 reserve capacity rating is 140 minutes. The OPTIMA Group 34 battery is an AGM (absorbed glass mat) lead-acid battery, while the Group 24 is a flooded lead-acid battery. The OPTIMA uses 99.99% pure virgin lead, which reduces corrosion, while the Group 24 battery uses recycled lead. OPTIMA indicates our batteries can last up to three times as long as a traditional flooded lead-acid battery, which can more than make up for the additional up-front expense.

So can you use a Group 34 battery in an application that had a Group 24 battery in it before? As long as the specifications (whether that is cranking amps or reserve capacity) for the application are met or exceeded by the Group 34 battery and it fits safely in your application, you can absolutely replace the Group 24 battery with a Group 34 battery.

Whichever battery you choose for your application, make sure to keep the battery voltage properly-maintained. Fully-charged, most batteries will measure at least 12.6 volts, while our D34M BLUETOP will measure about 13.0-13.2 volts. We're so confident battery performance and lifespan will be maximized by maintaining proper battery voltage, that we will extend the warranty by a full year on any battery you purchase from us, if you buy an OPTIMA Digital 1200 battery charger from us at the same time (they also work great on flooded lead-acid batteries).