can you use marine batteries in cars

[AndrewLynn]

While a marine battery might physically fit and temporarily start your car, it is generally not a safe or reliable long-term replacement. The core issue lies in their fundamental design differences: car batteries are optimized for a short, high-power burst to crank the engine, while marine batteries are built for deeper, slower discharges to power accessories like trolling motors and electronics. Using a marine battery in a car can lead to poor starting performance, especially in cold weather, and significantly shorten the battery's lifespan due to vibration damage.

The most critical difference is the Cold Cranking Amps (CCA), a rating that measures a battery's ability to start an engine in cold temperatures. Car batteries have very high CCA ratings (typically 500-800 CCA) to deliver the necessary power instantly. Marine starting batteries have lower CCA, and deep-cycle marine batteries have very low CCA, making them unsuitable for reliable engine cranking.

Furthermore, car batteries are engineered with robust internal construction to withstand the constant vibration and shock experienced on roads. Marine batteries lack this same level of vibration resistance, meaning the internal plates can degrade and short out prematurely when used in a car. This can also pose a safety risk. In a pinch, a marine starting battery could work for a few starts, but you should replace it with the correct automotive battery as soon as possible.

Feature	Automotive Battery	Marine Starting Battery	Marine Deep-Cycle Battery
Primary Function	High-power burst to start engine	Start marine engine; limited accessory power	Slow, steady power for accessories (trolling motors)
Cold Cranking Amps (CCA)	High (e.g., 600 CCA)	Moderate (e.g., 400 CCA)	Very Low (e.g., 100 CCA)
Vibration Resistance	Excellent	Fair	Poor
Cycle Life	Low (designed for shallow discharges)	Moderate	High (designed for repeated deep discharges)
Plate Design	Thin plates for max surface area	Thicker than automotive	Very thick plates for durability

[ZoeyLee]

I tried it once when my truck battery died and I had my boat nearby. It worked to get me to the auto parts store, but the guy there told me I was lucky it didn't cause problems. He said car batteries are built tougher for all the bouncing around on the road. A boat battery isn't, so it could shake apart inside. It's a temporary fix at best, not a real solution.