When it comes to batteries, choosing the right type for one’s boat can create a bit of a conundrum. So, to make this selection as simple and as straight forward as I can, I’ll give my opinions and reviews of the three main battery types.
Firstly, there’s the good old fashioned flooded lead acid battery. We have been using flooded lead acids for years and they are a proven success. That being said, they have their advantages and disadvantages. The chiefest benefit of a lead acid is that they are readily available. They are carried just about everywhere and in the common sizes anglers would use, such as 29 or 31. On top of that, they are the cheapest battery type used as both trolling motor and cranking batteries. The problems faced by the lead acids are their lifespan, need for maintenance, a need for two different types. Two variations need to be used for trolling (deep cycle) and cranking (cranking specific) to not damage the battery. They need to have the right amount of distilled water added to them from time to time, or else their capacity will rapidly deplete and they will be damaged. Even with the right maintenance, however, these batteries just don’t last long. Personally, a year or two is about what one can expect from a flooded lead acid battery. After that, you’re just gambling by hoping one will last. With those faults in mind, I have still chosen to run flooded lead acid batteries at times. I can put together three group 31 interstate deep cycle batteries for my trolling motor batteries and get along just fine. With interstates, too, if I notice a problem with a battery I can just head right on over to the nearest interstate dealer and grab a new one. Simple as that. As a cranking battery, I just can’t recommend the use of a flooded lead acid battery now though. We have too much juice headed to the electronics nowadays and they just can’t stand up to that well.
Next, we have the AGM (absorbent glass mat). AGM Batteries are dual purpose, meaning they can be used as a cranking battery or a trolling motor battery without damaging them. This is a really good thing considering that a cranking battery typically has a lot of power constantly being pulled from the fishfinders and other equipment running on the boat. They don’t require the maintenance of a flooded lead acid battery and can be purchased with a fairly large reserve capacity. Group 31 AGM batteries can run a boat rigged with two or three graphs as a cranking battery, though it might be pushing the limit of the battery some on a very long day. AGMs do need a charger that have a mode specifically for their type, but that is pretty common in most on-board chargers. In regards to the life of the battery, typically ‘you get what you pay for’ tends to be the rule. The higher the quality, and, therefore, the higher the price of the battery, the longer it’ll last (and also will come with more warranty). I still don’t find myself running an AGM for more than about three years. They will eventually lose their reserve capacity, simply meaning they run out of juice faster. A potentially big problem with these batteries, too, is their weight. These things are HEAVY. A single Group 31 AGM weighs around 70 pounds. Four of them for a 36v trolling system and cranking battery means adding 280 pounds. Not only is that a lot of cargo for the boat to carry, that means these batteries are difficult to get in and out of the boat and the compartments they go into. Despite this, AGM batteries are a good choice for cranking and not bad for trolling.
Lastly, the latest and greatest thing in the marine battery world are lithium batteries. Lithiums have numerous advantages, including their size and weight. A 125 Amp Hour Lithium Battery that would certainly be used as a cranking battery weighs in at only 34 pounds. That means only 136 pounds with four of those, and that’s with three 125Ah batteries being overkill when it comes to trolling. Most lithium batteries are dual purpose, eliminating the need for battery variations. Something unique to lithium batteries is their ability to put out 100% until they shut off. For instance, if I ran an AGM battery on a 12v trolling motor until it was dead, the last leg would be without as much power. If I run a lithium battery on a 12v trolling motor until it is dead, I get completely full power until the end. Part of this trait comes from the inclusion of a computer regulator in lithium batteries. Being more volatile than traditional battery types, Lithiums cannot get too much charge or too little charge or else they could overheat and burn up anything around them. The early days of lithium batteries in boats did see some of these instances; however, that has since been almost completely remedied by the newer regulators in lithium batteries. When in comes to flat out lasting on the water, I think lithium batteries are unbeatable. With a 125ah cranking battery and three 100ah trolling motor batteries (only 118 pounds), I can go and go and go without any worry as to whether or not I am going to get low on juice. Not only that, but lithiums charge extremely fast. Within a few hours, a very low lithium set up will be solid green across the board. Certain batteries, such as the Ionic Lithium batteries we carry here at Brushy Creek Marine, have handy features like bluetooth that allow me to check the charge of each battery whenever I want. Among the few disadvantages of lithium batteries are the operational temperature and need for a specific charger. Lithiums don’t fair so well in the cold, specifically temperatures below 24 degrees Fahrenheit. Personally, this is a non-issue for me as I do not ice fish, but northern fisherman may want to keep this in mind (some lithium batteries have their own internal heater I will mention). The glaring downside to lithium of course is their price. Currently, a 125Ah Ionic Lithium battery normally used as a cranking battery is $789.00. This is actually a terrific price for a lithium battery of that standard, but, still, is a big investment. To soften the blow, however, Ionic Lithium batteries come with their humongous 11 year warranty. No other battery type comes close to that type of warranty, so one can expect these batteries to last a very long time. Rather than be replacing flooded lead acid batteries or AGM batteries every so often, a single purchase could potentially last an entire decade.
In summary, with whatever choice one makes with his or her batteries, so long as it’s the right size, any of these battery types will work just fine. That being said, lithium is king in my mind. With the prices having fallen down to a reasonable deal and the warranty that Ionic and other brands come with, I just can’t imagine AGM, or much less flooded lead acid batteries, being a better option. The ability to purchase a set of batteries to go on worry-free for a very long time and have the longest lasting, most powerful set up on the water gives me a peace of mind that I can’t quite achieve with AGMs or lead acids.
