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Walleye Boat Rebuild Part 5: Batteries and Chargers

Maximizing space with the right batteries and on-board chargers will power all accessories and limit frustration.

Walleye Boat Rebuild Part 5: Batteries and Chargers

The right batteries and on-board chargers are a critical part to a boat build. In Part 5 of this series, Robertson discusses in detail.

If you don’t think we have come a long way with fishing boats, buy a 20-year-old rig and compare it to a modern-day version. In the early 2000’s, we didn’t have as much power available with our trolling motors or graphs as we do today. Modern-day graphs easily pull three times or more power and when you compound that with the fact that anglers typically have an extra unit or two from what was the norm back then. Serious power issues became commonplace. More batteries also mean more chargers, and they take up space. A lot of measuring and decisions must take place before you just swap out batteries or chargers.


Originally, this boat was setup for a 24-volt trolling motor that would only require two batteries. In the boat’s prime, anglers still used the cranking battery to power their electronics as well. This would pose a problem for my objectives since I was planning to use a 36-volt trolling motor that acted as a backup for my big guide boat—a Ranger 622. This rigging would require three batteries rigged in series to create a 36-volt system. The same goes for electronics, with multiple large screen Humminbird Helix units planned for the boat, a separate battery for those would also be required.

old crank battery
The author still runs a traditional lead-acid crank battery, and it only runs motor functions and built-in boat accessories, not electronics.
empty battery port
This spot was designed to accommodate two batteries to power a 24-volt trolling motor. Now it’s being reorganized to hold three lithium batteries to power a 36-volt trolling motor.

The good news is that the newer technology of lithium batteries means I can get a lot more power in a smaller platform with much less weight. I choose to go with Dakota Lithium 135-amp-hour batteries for several reasons. They are the size of Group 24 batteries and that would allow me to fit three batteries in the same space where originally there were only two Group 31 series batteries. The caveat being that I would need a different style of battery tray because of the tight fit. A small custom size aluminum tray allowed me to secure the tray from directly beneath them and not with the flared-out sides of a traditional plastic battery tray. The aluminum trays allowed for a literally side-by-side mount and just enough room to fit.

Another reason for the Dakota Lithium 135 selection is that these batteries are dual purpose and can be used to jump start another battery, which many lithium batteries cannot be used for this purpose.

Custom battery tray
It’s important to secure all batteries, here I had some custom trays fabricated to accommodate the exact footprint of the Dakota Lithium 135AH batteries. Easy and inexpensive.
custom battery trays installed
Here’s a shot of the battery trays installed ready for the Dakota Lithiums.

If your boat did not have a trolling motor make sure to add a breaker specific to just the trolling motor batteries before wiring up the batteries. It’s also a good idea to run your trolling motor from these batteries exclusively and leave other accessories to another independent battery.


All of these batteries need a way of being charged and required a modern-day charger. I have relied on Minn Kota Precision Chargers for years, and the latest models have a lithium setting to get the maximum amount of use out of the batteries.

I choose two 3-bank chargers to charge the six batteries for a very specific reason. First it was going to be easier to place the two chargers on the vertical walls of the transom supports and the 3-bank model was available in a 15-amp version. Many of the lithium onboard chargers on the market are only available in a 10-amp version, and this would just take a lot longer to charge a 135-amp battery, particularly on those long days of fishing, which result in short nights to charge.

batteries installed
Here you can see three batteries in place of what previously only allowed for two. The smaller footprint of Dakota Lithiums makes this part easy and satisfying.

When installing the chargers, make sure to find a dry place where they will have plenty of air flow. By using a couple small blocks of starboard behind each attachment point, places the charger away from the mounting surface to promote more air flow. That helps keep the charger cool and allows it to work faster.

installed battery chargers and batteries
Here’s the finished power plant, complete with two Minn Kota Charger and a handful of Dakota Lithium batteries. And it works perfectly.

Spend some time researching what batteries and chargers will work best for your situation and budget, particularly having the right footprint to maximize space in your rig. Many anglers get sticker shock with lithium batteries, and it can be eye opening at face value, but when you consider that my Dakota Lithium batteries have a 11-year warranty and will last longer than three or four sets of traditional lead-acid batteries, you actually pay less in the long run and have a much better product.

Capt. Ross Robertson

Bigwater Fishing


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