If you are thinking about purchasing a Lithium Iron Phosphate (LifePO4) battery for a new trolling motor or maybe upgrading an existing system, you are probably thinking to yourself “How much juice do I need and how do I charge it?” We are here to help you with that. We obviously love selling lithium-ion batteries, but our goal is not to sell as many as possible. Our goal is to get the right equipment into the hands of the people who demand the highest performance available in a marine battery.
You have done some research and you know marine grade lithium iron phosphate batteries are way lighter, charge extremely fast, and have loads (no pun intended) more capacity than lead-acid and absorbed glass mat (AGM) batteries. Our batteries, like most leading LifePO4, can be drained down 100%, and brought back up safely, over and over and over again without causing damage to the internal components or altering the functionality of the batteries. However, most users will never find the bottom of their battery if they use our advice in this article combined with monitoring the battery via the ABYSS Battery Bluetooth App. Did I mention all of our batteries are available with Bluetooth?
Size Matters (Boat Length)
So now, you may be thinking, “If lithium iron phosphate has more capacity, more output, charges faster than lead-acid or AGM batteries, lasts longer (10- year warranty), and takes up less space, now I really don’t know what to buy. I am replacing three 12V lead-acid batteries!” The good news is we have been there as boat owners and competitive fishermen and can tell you that it's actually very simple. With trolling motors, we are going to base the size of the recommended battery on the size of the boat you are wishing to troll with. For example, the guy with a Cobia 240 isn’t going to need the same sized battery capacity as the tournament team on the Yellowfin 42 spending 48 hours on the water fishing all day and all night in moderate conditions.
Just for fun, let's say the Cobia and the Yellowfin both have 36V Minn Kota Riptide Terrova, 60” and 72” trolling motors, respectively. Yes, the consumption maybe a tad higher on the Yellowfin due to 12” more shaft to spin, but for comparison of the batteries, I think it's ok to leave that detail out because the difference there is minimal, and there are really only a few choices to choose from when selecting a trolling motor battery. The biggest difference between the two boats in regards to how hard the trolling motor is going to work and how many amp-hours the system is going to consume is obviously, the size of the boat! The trolling motor on the Yellowfin is going to work almost twice as hard as the trolling motor on the Cobia while maintaining a GPS hold in 8 knots of wind, but on the other hand, the Yellowfin has a lot more space for battery storage.
Choosing The Right Battery Charger
There are a few methods of charging your trolling motor and depending on how you are set up, it may influence the capacity you decide to go with. The first and the one I believe to be the most common method of charging trolling motor batteries amongst offshore and inshore fishermen is to have a starter battery wired to the outboard alternator, and a separate trolling motor battery with a charger featuring a 110/120 plug. Having a charger you can plug into the wall when you get home or plug into the lift is the cheapest way to charge a stand-alone trolling motor system. The downside to this system, obviously, is heavy repeated use without charging the trolling motor battery will result in, well, a dead trolling motor battery. For 99% of users, their boat is near 110V/120V outlets more often than every few days, so something like our On-Board 36V 15A High Precision Lithium Charger works perfectly at supplying the trolling motor battery with enough juice to fish a multi-day tournament in moderate conditions.
This charger mounts inside your boat, and you simply plug it into an extension cord when you are done fishing for the day/weekend. This charger takes the 110/120 from the outlet on your boat lift/dock and turns it into the proper voltage for charging your lithium iron phosphate trolling motor battery. Did I mention our batteries also make great starting batteries, some with cold cranking amps in the thousands?
Now, the above setup is not the only option. Maybe you want or need the ability to charge your lithium iron phosphate batteries while running your outboards offshore or for days on end. This can be done with a Power-Pole CHARGE Marine Power Management Station. This is basically a battery charger that can be used with different types of batteries on your boat. If you are running a 36V lithium trolling motor, and have a 12V starting battery, then the Power-Pole CHARGE is for you. This system will take the ~70 amps from your outboard alternator and feed it safely into your starter battery and into your Abyss LifePO4 trolling motor battery, simultaneously, and back and forth when needed. Pro-tip, using proper equipment is key to keeping a setup functional.
More Amp Hours = More Run Time
Finally, we only have a few sizes when it comes to trolling motor batteries, simply because they charge so fast and last so long, we don't really need more options. In the 36V line, we have a 60AH, 80AH, and 105AH battery. To be honest with you, the 60AH battery is going to be perfect for just about everyone with a 33-foot boat or smaller. When we get into the heavier two engine and triple engine 36-42 foot offshore center consoles (10,000-12,000lbs) we are going to be looking at the 80AH and 105AH batteries, possibly two 60’s wired together for 120AH if the spaces are tight. However, a large boat like the 42 or 46 foot doesn't necessarily need 120AH of lithium, especially if they are running a Power Pole to charge their trolling motor battery from the outboards. We can also wire three 12V 120AH batteries together to make a 36V 120AH bank if the user would like to run like that. We would only suggest that much battery capacity if someone said “I want too much power because overkill never fails. I make dead fish every day."
I hope this article helps with your decision on which battery to choose when selecting one of our LifePO4 batteries for your offshore and inshore fishing adventures. As always, if you have any questions or this article didn’t help with your decision. Please give us a call, we like to talk about our batteries.