One of the best ways to improve the performance of a jet boat is to reduce weight and one of the best ways to reduce weight is to replace the batteries with lithium. The weight reduction is amazing. The battery has more useful voltage than a comparable AGM or lead acid battery and they are built to last longer (10+ years). The only cons to lithium batteries are cold weather charging and the price.
I was experiencing a no start issue in my boat after upgrading my electronics. Specifically after adding a new 10” Garmin 106SV and Panoptics Livescope transducer. My start battery was an Optima Bluetop 55AH D34M, which I’d previously had nothing but good luck with. I highly recommend them but lithium is such a better option specifically in an Outboard jet powered boat. Over twice the power and run time at half the weight.
An Outboard Jet by design can carry 25 lbs per power head horsepower. So an Outboard Jet with 115 powerhead horsepower (80 Jet horsepower) would be able to transport a load of 115 * 25 = 2,875 lbs. That’s the captain, hull, fuel, tackle, drinks, passengers, everything. So every 25 lb reduction in weight is equal to gaining 1 HP for your engine and those of you currently with an outboard jet you understand that an Outboard Jet simply cannot handle being overloaded. Less is more and changing out to lithium batteries can help drastically.
I replaced the Optima, which was the only battery in my boat running the 12-volt system. It starts my 115/80 Yamaha Jet and powers every electronic on the boat except the trolling motor. To replace it I ordered a Weize 12V 100AH LiFePo4 Battery from Amazon. I’d read many reviews and watched several tear down videos on lithium batteries to understand how they work. To save you the trouble, this brand uses high quality cells and parts. Of all the manufacturers this battery is great value for the price.
|10” x 6-⅞” x 7-13/16”
|12.7” x 6.49” x 8.34”
The Weize 100Ah is a direct fit into a Marine 31 series battery box as you can see below. So for many boats this is a plug and play change out. The Weize as with most lithium batteries does not come with terminal studs. Instead there are metric M8 bolts used to thread down into the aluminum base of each terminal. The bolts provided are not very long so if you currently have a large number of spade connectors on each terminal you may need to either move those off to a circuit panel or, my preference, thread in some studs with loctite and use nuts like a standard marine battery. Either way be careful with the stud bases. They are made of aluminum and could be stripped out with too much torque
Lithium batteries operate at a much higher voltage than standard lead acid batteries as well as AGM batteries. You will need a charger that is designed specifically for charging lithium batteries. I chose to go with the NoCO Genius 5×1 single bank on-board charger for my installation. The NoCo can be adjusted for the specific type of battery that you have and has served me well thus far. It has large lights to indicate the state of charge and mode which is helpful with it being installed below deck. It’s easy to peak in through a hatch to see if it’s ready for action.