Onboard Chargers for 24V & 36V Trolling Motors on Your Barletta | Bank Wiring, Series Basics, and a Setup That Lasts
The trolling motor is mounted, the batteries are in the locker, and the last thing you want to do after a long day on the water is pull three batteries out to charge them one at a time.
That’s the quiet appeal of an onboard charger. It lives in the boat, connects permanently to each battery, and turns charging into a single shore power cord at the dock. On a luxury pontoon boat like your Barletta, where the bow-mount trolling motor is an add-on rather than a factory default, getting the charger setup right means understanding how 24V and 36V systems differ—and why “one bank per battery” is the rule that keeps things simple.
TL;DR
A 24V trolling motor uses two 12V batteries wired in series. A 36V system uses three. For charging, you need a multi-bank onboard charger with one bank per battery—a 2-bank charger for 24V, a 3-bank charger for 36V. The charger connects to each battery individually, not to the series string as a whole. Mount the charger in a dry, ventilated space, fuse each positive lead within 18 inches of the battery, and let a marine electrician handle the AC shore power connection if you’re not experienced with it .
Key Takeaways
- One bank per battery, not per system. A 24V system with two batteries needs a 2-bank charger. A 36V system with three batteries needs a 3-bank charger .
- Series wiring creates the voltage. Two 12V batteries in series make 24V. Three make 36V. The charger still connects to each 12V battery individually .
- Match charger amps to battery capacity. A common rule is at least 10% of your battery’s amp-hour rating. A 100Ah battery wants at least 10 amps per bank .
- Fuse every positive lead. Install an inline fuse within 18 inches of each battery. A 15A fuse is typical for a 6A bank charger .
- AC wiring is not DIY territory. The DC side is manageable for a confident owner. The shore power inlet and AC connection should be handled by a certified marine electrician .
- Always wear life jackets and follow local boating laws when operating any vessel.
Series Wiring Basics: What Your Trolling Motor Needs
Before you buy a charger, you need to understand what you’re charging.
A 12V trolling motor runs off one battery. A 24V motor needs two 12V batteries wired in series. A 36V motor needs three . Series wiring adds voltage while keeping amp-hours the same. Two 100Ah 12V batteries in series become a 24V, 100Ah bank. Three become 36V, 100Ah.
The series connections look like this:
24V system (two batteries):
- Jumper from Battery 1 positive to Battery 2 negative
- Motor red lead to Battery 2 positive
- Motor black lead to Battery 1 negative
36V system (three batteries):
- Jumper from Battery 1 positive to Battery 2 negative
- Jumper from Battery 2 positive to Battery 3 negative
- Motor red lead to Battery 3 positive
- Motor black lead to Battery 1 negative
All batteries in a series bank should be the same type, size, and age. A weak battery drags down the whole string .
Does your current trolling motor setup match the voltage on the motor label?
Why “One Bank Per Battery” Is the Rule
Here’s where a lot of DIY installs go wrong. The charger doesn’t connect to the 24V or 36V output. It connects to each 12V battery individually.
A multi-bank charger treats each battery as its own charging zone. Bank 1 goes to Battery 1’s positive and negative. Bank 2 goes to Battery 2’s positive and negative. Bank 3 goes to Battery 3 .
This matters because the batteries in a series string can drift out of balance over time. One battery may accept charge differently than another. A multi-bank charger conditions each battery independently, which extends the life of the whole bank.
What you need:
| System Voltage | Batteries Required | Charger Banks Needed | Typical Charger |
|---|---|---|---|
| 12V | 1 | 1 | 1-bank, 10A |
| 24V | 2 (series) | 2 | 2-bank, 10A per bank |
| 36V | 3 (series) | 3 | 3-bank, 10A per bank |
A 3-bank charger for a 36V system also gives you a spare bank for a starting battery if your Barletta has one, but don’t mix chemistries on the same charger unless the charger supports it .
Have you counted your batteries lately—two or three?
Choosing the Right Charger for Your Barletta
Not all onboard chargers are created equal. Here’s what separates a good marine unit from a cheap one.
Bank count. Covered above. Two batteries, two banks. Three batteries, three banks.
Amp output. The 10% rule is a good starting point. A 100Ah battery wants 10 amps. A 50Ah battery can get by with 5 amps, but faster charging is usually worth the extra cost. Most quality marine chargers run 5–10 amps per bank for trolling motor batteries .
Battery chemistry support. Modern chargers should handle flooded lead-acid, AGM, gel, and lithium. If you’re upgrading to lithium trolling batteries later, buy a charger that supports them now .
Waterproof rating. Look for IP67 or higher. The charger lives in a boat, and boats get wet. Splash resistance is not optional .
Ignition protection. If your charger is anywhere near a gas engine or fuel tank, it needs ignition protection under Coast Guard rules. This is a legal requirement, not a nice-to-have .
Temperature compensation. Good chargers adjust voltage based on temperature. Cold batteries need different charging voltages than warm ones. A temperature sensor or built-in compensation protects your batteries and improves charging accuracy .
| Charger Feature | Why It Matters | Minimum Spec |
|---|---|---|
| Banks | One per battery | 2 for 24V, 3 for 36V |
| Amps per bank | Charging speed | 10% of battery Ah |
| Chemistry support | Correct charging profile | Flooded, AGM, gel, lithium |
| Waterproof rating | Marine environment | IP67 |
| Ignition protection | Legal requirement near fuel | Required if near engine space |
Battery Tender’s WaveCharge series is one example of a marine onboard charger designed for multi-battery systems. Minn Kota also makes onboard chargers specifically for trolling motor setups .
Are you buying for today’s batteries or planning for a future lithium upgrade?
Mounting and Wiring the Charger
The install is straightforward, but the details matter.
Mounting location. Dry, ventilated, and accessible. Never in the bilge where standing water can reach it. Allow at least 2 inches of clearance on all sides for airflow—chargers get warm during operation . Some manufacturers recommend more, so check the manual.
DC wire size. 10 AWG is typical for runs under 10 feet to each battery. Longer runs may need larger wire to minimize voltage drop. Use marine-grade tinned copper wire, not automotive wire .
Fusing. Install an inline fuse on each positive lead within 18 inches of the battery. A 15A fuse is standard for a 6A bank charger. For a 10A bank, use a 20A fuse. The fuse protects the wire and the charger if something shorts .
Terminations. Marine-grade ring terminals and heat-shrink tubing on every connection. Crimped connections are more reliable than solder-only in a vibrating marine environment. Apply heat-shrink to seal out moisture .
The AC side. This is where you stop if you’re not comfortable. The shore power inlet and AC wiring require marine-specific standards for cable routing, connection methods, and safety equipment. Many owners do the DC wiring themselves and hire an electrician for the AC portion .
Route DC cables away from AC cables and any sources of interference. Keep runs as short as practical. Every foot of wire adds resistance and reduces charging efficiency .
Do you have a dry spot picked out, or is the charger going in the locker next to the life jackets?
Chart: Charging Time by Bank Amps and Battery Capacity
The chart assumes a partially discharged battery and a multi-stage charger. Real-world times vary with depth of discharge and charger profile.
Comparison: Charging Options for Trolling Batteries
| Option | How It Works | Best For | Pros | Cons |
|---|---|---|---|---|
| Multi-bank onboard charger | Permanent mount, one bank per battery | Regular trolling motor use | Charge all batteries at once, maintain properly | Higher upfront cost, AC install required |
| Portable bank charger | Carry-on, clamp or ring terminals | Occasional use, multiple boats | Cheaper, no installation | Manual connection each time, easy to forget |
| Single-bank charger + rotation | Charge one battery at a time | Budget setups | Lowest cost | Slow, batteries drift out of balance |
| Solar maintainer | Trickle charge from panel | Storage, no shore power | No AC needed | Slow, not for deep recharge |
For a Barletta with a dedicated bow-mount trolling motor, the multi-bank onboard charger is the right long-term choice. It eliminates the “did I charge all three?” question and keeps the batteries balanced.
FAQ: Onboard Chargers and Trolling Motors on a Barletta
What makes Barletta boats unique for trolling motor setups?
Barletta builds barletta pontoon boats with stable platforms and generous under-seat storage that can accommodate battery banks. The full-length crossmembers and solid deck structure give you mounting points for chargers and wiring runs.
Are Barletta pontoons good for beginners adding trolling motors?
Yes. Pontoon boats are stable and predictable. The Corsa’s hydraulic steering systems and manageable power make it easier to focus on the electrical setup when you’re new to trolling motor installs.
How fast can a Barletta pontoon go with a trolling motor?
Trolling motors are for slow, precise maneuvering, not speed. The main outboard does the cruising. Trolling motor speed is measured in mph single digits, depending on thrust and conditions.
What engine size is best for a Barletta boat with a trolling motor?
A 150–200 hp outboard handles family cruising. The trolling motor is a separate system for fishing and positioning. Match the trolling motor thrust to your boat’s weight and conditions.
Are Barletta boats safe for families with trolling motor batteries?
Yes, with proper installation. Always wear life jackets and follow local boating laws. Secure batteries and chargers, fuse all positive leads, and keep electrical connections away from water and fuel.
What maintenance does a Barletta boat require for onboard chargers?
Check charger connections each season, verify fuses are intact, and clean terminals with a wire brush if corrosion appears. Confirm the charger is set to the correct battery chemistry.
Can you use a Barletta boat for water sports with a trolling motor mounted?
Yes. The trolling motor is stowed when not in use. Just ensure the mount and wiring don’t interfere with swim platform access or tow sports.
The Bottom Line on Onboard Charging
A multi-bank onboard charger is one of those upgrades that makes boat ownership feel easier. No more pulling batteries. No more guessing whether all three are charged. Plug in one cord at the dock, and the system handles the rest.
The key is matching the charger to the system: two banks for 24V, three banks for 36V, one lead per battery, fused and sealed. The DC side is a Saturday project. The AC side is a call to an electrician. Do both right, and your trolling batteries will last longer and perform better.
What’s your favorite Barletta boat feature or on-the-water experience? Share your thoughts in the comments below.
References:
- Johnson Outdoors (Minn Kota) – Connecting Deep Cycle Batteries in Series or Parallel
- Battery Tender – Battery Charger Installation Guide: Hardwired Onboard Setups
- Minn Kota – How to Wire Batteries in Series and Parallel [24 & 36 Volt Trolling Motors]
- EcoFlow – On Board Battery Charger Guide: How to Choose for Your Boat
