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When you opt for a 24-volt or 36-volt trolling motor battery (often a single lithium-ion unit), you're making a choice that prioritizes efficiency, longevity, and peace of mind. Here's why:

1. Inherent Cell Balance: The Undeniable Advantage

This is where the 24V or 36V system truly shines. Consider a typical lithium-ion battery. It's not one giant cell, but rather a pack of individual cells wired together in series.

• 12V Battery: A single 12V lithium-ion battery typically consists of 4 cells wired in series (4S configuration).

• 24V Battery: A single 24V lithium-ion battery typically consists of 8 cells wired in series (8S configuration).

• 36V Battery: A single 36V lithium-ion battery typically consists of 12 cells wired in series (12S configuration).

The critical point here is that all cells within a single 24V or 36V battery are managed by a single, integrated Battery Management System (BMS). This BMS is constantly monitoring the voltage, temperature, and current of every single cell within that battery pack. If one cell starts to drift slightly in voltage, the BMS will actively balance it with the others, ensuring they all charge and discharge uniformly. This proactive balancing is continuous and automatic. More info on this can be found if you skip to 8:10 in this video here.

2. The Pitfalls of Series 12V Batteries

Now, let's look at the alternative: wiring two or three 12-volt batteries in parallel to achieve 24V or 36V.

• No Centralized Balancing: When you connect multiple 12V batteries in series, each 12V battery has its own internal BMS if we are talking about most lithium batteries... or no BMS at all for standard lead acid. These individual BMS units are only concerned with balancing the cells within their own battery. They have no awareness of, or control over, the cells in the other 12V batteries in the parallel bank.

• "Fighting" Among Batteries: Over time, slight manufacturing tolerances, varying internal resistances, or even just different charge cycles can lead to imbalances between the 12V batteries. One battery might try to "push" more current than another, leading to inefficient power delivery and accelerated wear on the less dominant battery.

• Reduced Lifespan: This lack of external balance between parallel batteries can lead to one battery being consistently overcharged or undercharged relative to the others. This significantly reduces the overall lifespan of the battery bank as the weakest link dictates the performance of the entire system. You might find yourself replacing batteries more frequently.

3. Simplicity and Reliability

A single 24V or 36V battery simplifies your wiring, reduces connection points (which are potential failure points), and generally leads to a more robust and reliable system. Fewer components mean less to go wrong.

4. Optimized Performance

With all cells within a 24V or 36V battery working in perfect harmony, your trolling motor receives a consistent and optimized power supply. This can translate to better sustained thrust, longer run times, and overall more enjoyable time on the water.

We have found the 24 and 36V batteries to be especially reliable versus 12v batteries when running an Ulterra trolling motor as the motors are very voltage sensitive. 

One thing to be mindful of when selecting a 24v or 36v battery is the dimensions. Many manufacturers have odd sizes that require modifications or special trays. One of the reasons we prefer these batteries is that they fit an off the shelf battery tray and often times you can just drop them right in your boat with no hassle.

Conclusion

While the initial cost of a single 24-volt or 36-volt lithium-ion battery might be slightly higher than purchasing multiple 12-volt batteries, the long-term benefits in terms of cell balance, lifespan, reliability, and performance make it a truly worthwhile investment for any serious angler.