If you have a boat with onboard electrics, then yes. Onboard chargers plug into the onboard power circuit in your boat and deliver charge to your battery. The best onboard battery chargers – such as the Minn Kota Precision -work with both AGM and flooded cell batteries and can charge banks of multiple batteries.

The main terms you will see mentioned in marine batteries are CCA (cold cranking amps), CA (cranking amps), AH (amp hours) and RC (reserve capacity).

As explained on the Battery Stuff website:
Cold cranking amps (CCA) is a measurement of the number of amps a battery can deliver at 0°F for 30 seconds and not drop below 7.2 volts. A high CCA battery rating is especially important in starting battery applications, and in cold weather.

CA is cranking amps measured at 32°F. This rating is also called marine cranking amps (MCA).

Reserve Capacity (RC) is the number of minutes a fully charged battery at 80°F will discharge 25 amps until the battery drops below 10.5 volts.

An amp hour (AH), as discussed above is a measure of the amount of power stored in the battery. The standard rating is an amp rating taken for 20 hours. What this means for a 100 AH rated battery is this: Draw from the battery for 20 hours, and it will provide a total of 100 amp hours. That translates to about 5 amps an hour. (5 x 20 = 100).

The best thing to while storing your AGM battery is to keep it charged. Storing an AGM battery in a discharged condition can damage it and reduce its capacity. Remember also to store batteries in a well ventilated place.

These are similar to AGM batteries in that they are fully sealed, leak proof and spill proof. They can also be mounted in any position. Performance wise, they are fine for operating a trolling motor but they tend to be more expensive that AGM batteries and the performance advantage is not high enough to warrant the extra cost. They also require a special type of charger.

Lithium ion batteries are the best in terms of performance – they boast a superior power to weight ratio and are fast to recharge and reasonably durable. But for operating a trolling motor, which consumes a large amount of energy, it is arguably overkill to use a lithium ion battery, especially given the high cost in the capacity required. We think if you really need that high performance for light weight – such as for kayak fishermen – then lithium iron phosphate is a better bet. These batteries are cheaper and have a better safety profile than lithium iron and the best models are specially designed for marine applications.

Almost all trolling motors run on 12V power. For big boats, you can get 24V motors, but that’s rare. For these motors hooking up two 12V batteries is generally the easiest power solution.

The answer is that you can! And they are cheaper. But with the lower upfront cost comes higher maintenance costs over the years – you need to top up the cells and cleaning the terminals relatively frequently to remove corrosion. Then there is the possibility of spills. No one wants acid sloshing around the bottom of their boat or kayak! So if you can possibly afford the upfront cost, we will always say avoid the wet cell batteries and consider a maintenance-free AGM battery instead.

As a general rule, count on five years for an AGM battery and 10+ for a lithium iron phosphate battery. A wet cell battery’s life is more like 2 years in this application.

This will depend on your circusmtances, but best practice with AGM batteries and the other types is to charge them once you have finished your fishing session and then store in a cool dark place.

No! Car batteries are designed to supply high cranking power for short bursts, whereas for a trolling motor you need slow steady power output over a long period of time. You also need a battery that you can substantially deplete without it losing voltage or performance. That means a deep cycle battery. A car battery certainly doesn’t have these characteristics and will let you down if you attempt to use it to power a trolling motor.

A deep cycle battery is a battery that is designed to produce steady power output over an extended duration and continues to produce consistent power output through various stages of depletion. All the batteries listed here can be considered “deep cycle” batteries.

That depends on the output of the charger, but generally you should think about charging AGM and wet cell batteries overnight whereas lithium ion and lithium iron phosphate batteries may be fully charged within a few hours of being connected to the charger.

There are cheaper battery options available than the high quality batteries listed here, but it really is a false economy looking at these options for these reasons:

Reliability – with no brand behind these batteries you can’t be sure of their quality. Boating is one of those activities where you put in a lot of time and money to get out on the water. You don’t want your trolling motor battery failing you when you do get a chance to get out and fish.

Safety – no only the safety of you and your loved ones (you certainly don’t want the trolling motor battery failing with your kids of wife on board), but also of your local waterway. Using inferior AGM batteries mean you run the risk of the casing cracking and leaking into your boat and into the water.

Durability – you need a battery that is going to last as long as the state lifetimes we give in this article for each class of battery. Hopefully it lasts longer and in many cases they will, but if you buy and cheap, inferior no name battery you are running the risk of it failing and having to be discarded after a few trips.