There are several different kinds of lead acid batteries that vary from the standard car battery, and quite a few people are confused by the differences. There are marine batteries, made for use in boats, and a marine deep cycle battery that are made for use in boats especially to run appliances or trolling motors. These two types of batteries differ from car batteries in several key areas that are very important for their care, maintenance, and usage, let's take a look now.
The Marine Or RV Designation Involves The Construction Inside
Many people that have never opened up a lead acid battery and looked inside will tell you that RV, marine and automotive batteries are identical, well they're not. A regular automotive battery can't take the same abuse physically that a marine battery is made to handle.
Face it, when you're in a boat slamming the waves hard it rattles the fillings out of your teeth. In addition to that, many times the bow of the boat is pointed straight up into the air one minute, then nearly straight down the next. A car battery isn't made to handle that on a consistent basis and will fail earlier than a real marine battery.
The reason is that the lead plates inside the batteries are built differently in order for the marine battery to take all of that pounding and not have the plates move together and short out. If you were to open up the two different types of batteries you'd notice the different layout of the plates and more reinforcements or spacers holding them apart in the marine battery.
The Marine Battery Construction Comes In Several Different Usage Models
Once you understand what the "marine" label designation really means for that type of lead acid battery, then you can better understand that there are several different types of marine batteries available depending on the projected use.
Some marine batteries are made to start the engines so they have a lot of cold cranking power much like a strong car battery would. They can withstand high power draws for 15 or 20 minutes to start the engines, then they want to be recharged again. However, they don't like to be drained all the way down in power, that's actually bad for them and can ruin them quickly.
A deep cycle marine battery is primarily made to run electric trolling motors, onboard refrigerators, electronic equipment, and other long-term, low-power draining. They can handle being drained nearly all the way down without harming the battery. However, they should never be used in a high drain application like starting a large motor, as that will cause a shortened lifetime and may not work to start the engine either.
And now when you go to buy your deep cycle marine battery you'll know exactly what you're looking for and won't be confused by the "marine" designation that you read. By getting the right kind of battery you'll get much longer usage and far fewer failures while boating.