While most push lawn mowers are pull-started, a few walk-behind and almost all self-propelled, riding lawn mowers feature electric starting, which makes it easier to start their larger engines. Just like batteries in cars and trucks, the lawn mower battery makes this convenience possible. With proper use and maintenance, a typical battery might last three or four years, perhaps longer in a warmer climate. Still, it will eventually corrode or sulfate, gradually suffering reduced power output, ability to keep a charge and ability to start.

Then, the starter solenoid might not even click when it comes time to mow the lawn, which means you’ll need to replace your lawn mower battery. Fortunately, most lawn mower batteries fall into the 12 V Group U1 format, standardized by BCI (Battery Council International), but they aren’t all the same. There are two main characteristics that you need to match up to ensure the lawn mower starts and charges reliably: terminal position and cranking amps.

Terminal Position

Group U1 lawn mower batteries come in two varieties, U1L and U1R, which refer to terminal position. Group U1L lawn mower batteries feature the positive (+) terminal near the left corner, on top of the battery, while Group U1R batteries feature the positive terminal near the right corner.

While the internal construction of U1L and U1R batteries is identical, the terminal position is critical to the battery’s installation and connection to the lawn mower’s electrical system. Installing a U1L battery in a lawn mower that requires a U1R battery may be impossible, as the cables may not reach the terminals, and “stretching” the battery cable could lead to chafed insulation and a dangerous short circuit problem. Choose a battery designed to fit the lawn mower in question.

Cranking Amps

Larger engines are harder to turn, which makes battery output another critical factor in choosing a new battery. Battery output is measured in CCA (cold-cranking amps), which describes the amount of current the battery can deliver in 30 seconds at 0 degrees F, without dropping below 7.2 V. Choose a new lawn mower battery with at least the specified CCA required by the lawn mower manufacturer.

Choosing a lawn mower battery with too low a CCA might not start the engine at all, or, if it can start the engine, it may overtax the battery’s own construction and wear it out faster. On the other hand, a battery with a higher CCA will have no problems starting a smaller engine, but it won’t provide any added benefits.

Choosing the proper power rating for your lawn mower battery is important to keep your machine running effectively — and your lawn trimmed to perfection — for years to come.

Check out all the lawn and garden products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on choosing the right lawn mower battery, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

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