Onboard Battery Charging Explained: ProMariner vs. Mastervolt

There's nothing worse than getting back to the dock after a long day on the water, tying up and realizing your batteries are dead, or worse, waking up on the hook during an overnight trip to find your house bank has drained overnight.

Battery management is one of those topics that doesn't get nearly enough attention when people are buying a boat, but it absolutely should. At Sportsman, we think about it so you don't have to, which is why we offer two purpose-built, professional-grade charging options designed around how our customers actually use their boats.

Whether you're running inshore on a Masters 227 or pushing offshore on an Open 352 with a Seakeeper and full AC, we've paired the right charger with the right boat. Let's break both options down so you know exactly what you're getting and why it matters.

Option 1: The ProMariner ProTournament Elite 3 — Built for the Angler

Available on: Open 322, Open 302, Open 282, Open 262, Open 252, Open 232, Open 212, Heritage 321, Heritage 261, Heritage 231, Masters 267/267OE, Masters 247/247OE, Masters 227

Configurations: 2-Bank (charges House + Engine) or 5-Bank (charges House + Engine + Trolling Motor)

If you're buying one of our smaller to mid-size center consoles or bay boats and you want a reliable, fast onboard charger that handles your everyday charging needs, this is your charger.

The ProTournament Elite 3 is ProMariner's premier, professional-grade waterproof charger line and it's earned that reputation. Here's what sets it apart:

Specs at a Glance

• 2-Bank: 24 Amps total, charges two 12V batteries (up to 24V systems), full charge in 4–8 hours
• 5-Bank: 50 Amps total, charges up to five 12V batteries (up to 48V systems + engine), full charge in 4–8 hours
• Battery compatibility: LiFePO4 lithium, AGM, HP AGM and flooded lead-acid
• Waterproof rating: IP67, fully sealed against water intrusion
• Certification: UL Marine 1236 certified
• Input voltage: 120V AC (±10%), works down to 90 VAC

What makes this charger really shine is the Distributed-on-Demand® technology. Instead of splitting its output equally across all banks whether they need it or not, the charger intelligently directs available amperage to the battery that needs it most. The result is a fuller charge, faster, which is exactly what you want when you're trying to get back out on the water the next morning.

It also uses 5-Stage Digital Performance Charging: Analyze → Charge → Condition → Auto-Maintain → Monthly Storage Recondition. That last stage is huge for anyone who lets their boat sit for a while. The charger automatically reconditions your batteries once a month to prevent sulfation and extend battery life.

The Charge Status AC Glow Plug is a small but genuinely useful feature. It lights up in three different colors right at the power cord, so you can tell at a glance whether your batteries are charging, conditioning or fully maintained without ever stepping on the boat.

The 5-Bank version is specifically designed for boats rigged with a trolling motor, like our Masters models or a smaller Open with a Garmin Force Kraken. It can handle systems up to 48V, meaning it covers a 36V or 48V trolling motor battery setup plus your engine start and house batteries, all simultaneously.

Who should choose this? If you're an inshore angler, flats fisherman or a day-boat family who keeps their boat at home or at a dry storage facility and wants a simple plug-in charger that keeps all your batteries ready to go, the ProTournament Elite 3 is a no-brainer. It's fast, smart and tough enough to live permanently on the boat.

Option 2: The Mastervolt ChargeMaster Plus — Built for the Offshore Adventurer

Standard on: Open 402, Open 352

Available as an option on: Open 322, Open 302, Open 282, Open 262, Heritage 261, Masters 267/267OE

Specs at a Glance

• Output: 12V, 50 Amps across three output leads
• Charging technology: 3-Step+
• Battery compatibility: LiFePO4 lithium, AGM and flooded batteries
• Input: 80–275V AC, 35–70 Hz
• Shore power connection: Direct marina hookup included; home adapter (120V plug)
• Certifications: CE, ABYC, UL, cULus, SAE, CEC/DOE, ISO, ACMA

The Mastervolt ChargeMaster Plus is a different animal. This is the charger you need when your boat has become less of a day-tripper and more of an overnight adventure machine.

Think about what a fully loaded Open 352 carries: a Seakeeper gyro, full AC system, high-output stereo, multiple screens and navigation lights running all night. That's a serious load on your battery bank. A standard charger wired to individual batteries simply can't keep up with those demands efficiently. The Mastervolt was designed specifically to solve that problem.

Here's what makes it fundamentally different: instead of connecting to individual batteries, the ChargeMaster Plus leads are wired directly to the battery switch, allowing the charger to see and service the entire battery bank as a whole. It intelligently distributes its 50 amps across all three leads, sending full power to the most depleted battery first, then balancing across the bank as each battery approaches a full state of charge. You never have to think about it. It just works.

The shore power integration is equally impressive. If you keep your boat in an in-water slip at a marina, you plug directly into the dock's shore power and you're done. If you store at home, the included adapter lets you plug into any standard 120V household outlet. Whether you're back from a Bahamas run or just home from a weekend trip, your batteries are being cared for the moment you plug in.

Mastervolt's 3-Step+ charging also includes a pre-float function that prevents overcharging smaller batteries in a mixed bank, a critical feature when you've got different battery types or sizes working together in the same system.

Who should choose this? If you're running a larger center console and you use your boat for extended trips, overnight anchoring or marina stays, especially with high-draw amenities like a Seakeeper or full AC system, the Mastervolt ChargeMaster Plus is the right call. It's a whole-system solution, not just a charger.

So Which One Is Right for You?

Here's the simple version:

Day boat, inshore fishing, bay boat or dry storage → ProMariner ProTournament Elite 3

Pick the 2-Bank if you don't have a trolling motor for a single engine and house battery setup and the 5-Bank if you do. It's fast, smart and purpose-built for exactly how you're using the boat.

Larger offshore center console (26+), overnight trips, marina slips or high-demand amenities like a Seakeeper gyro-equipped model → Mastervolt ChargeMaster Plus

This is a whole-battery-bank solution that integrates with shore power and handles the load demands of a serious offshore build.

Both chargers are available through your Sportsman dealer and can be factory-installed on your new build. If you're not sure which one fits your setup best, reach out to us or ask your dealer. Battery management is one of those details we love getting right before you splash for the first time.