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Sodium Ion · Three-Terminal Architecture · Three Marine Sizes · SC-31 Featured

TRITON Sodium‑Ion Starting Batteries by SureCrank

SC31 · Safer. Stronger. Smarter. Engineered for marine reliability.

The SureCrank TRITON is a three-terminal sodium ion marine starting battery available in three of the most popular marine sizes — Group 31, Group 27, and Group 24. New chemistry that behaves the way a starting battery should. A new architecture that ensures the engine always has power — no matter what happens on the house side.

Engineered from real‑world marine installations and ABYC electrical principles.

All TRITON models come standard with Bluetooth wireless for our iOS and Android apps. You can monitor individual cell voltage, current state‑of‑charge, and internal temperature of the battery directly from your phone.

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TRITON SC-31 SureCrank Sodium Ion Marine Starting Battery
The Lineup

Three Sizes. One Architecture.

The SureCrank TRITON is available in the three most common marine battery sizes. The SC-31 is the flagship model — SC-27 and SC-24 share the same validated three-terminal platform.

Flagship Model
SC-31
Group 31
Nominal Size 13.0″ × 6.8″ × 9.4″ Typical Application Larger vessels, twin-engine boats, full house + start duties
Platform Variant
SC-27
Group 27
Nominal Size 12.4″ × 6.8″ × 9.4″ Typical Application Mid-size cruisers, center consoles, single-engine runabouts
Platform Variant
SC-24
Group 24
Nominal Size 10.3″ × 6.8″ × 9.4″ Typical Application Smaller outboard boats, PWC, compact single-battery installs
The Problem

Every Available Chemistry
Makes a Compromise.

Modern boats demand stable voltage, ECU protection, and reliable engine starts — but neither of the two available chemistries can deliver all three. AGM is outdated. LFP is risky. Sodium ion, with the right architecture, fills the gap neither can bridge.

AGM
The Old Standard
Outdated
  • Sags heavily under cranking loads
  • Voltage drop stresses modern ECUs
  • Designed for a simpler electrical era
  • Ages quickly under modern cycling patterns
  • Still used only because LFP is worse for starting
LFP
Excellent for House Banks
Wrong Job
  • BMS can disconnect during cranking
  • Disconnect during charging causes load dump
  • Load dumps destroy ECUs and electronics
  • Flat voltage curve confuses alternators
  • Superb for house banks — dangerous for starting
Sodium Ion
Built for Starting
Right Chemistry
  • Sloped voltage curve alternators understand
  • Natural current limiting — protects wiring & solenoids
  • No oxygen release — does not support combustion
  • No copper dissolution or dendrites at low SOC (unlike LFP)
  • Tolerates full discharge without damage
  • Cycle life far beyond AGM

Sodium ion is the right chemistry — but every sodium ion battery on the market was built using the same two-terminal architecture as LFP, with all the same BMS disconnect risks. The industry copied the wrong template. SureCrank TRITON is built differently — and the same architecture scales across all three models: SC-31, SC-27, and SC-24.

The Solution

One Battery.
Two Separate Paths.
Three Terminals.

The starter circuit needs to be direct and uninterrupted — exactly like a traditional lead-acid battery. So that's how the SureCrank TRITON is built. The start terminal connects straight to the cell stack with no BMS in the path. The house terminal routes all loads and charging sources through a dedicated BMS that monitors cell health, temperature, and balance.

If the BMS detects a fault, it isolates the house side. The starter path is never touched. The engine always has power. The alternator always has a battery connected. A load dump becomes impossible by design.

SureCrank TRITON Three-Terminal Architecture
⚡ Start Terminal

Direct, uninterrupted connection to the engine. No BMS in the path. No electronics to fail. Behaves exactly like a traditional lead-acid battery during cranking — predictable, stable, and reliable under any conditions.

Always Live · No BMS
Common
Ground
⚓ House Terminal

All electronics, loads, solar, shore power, and DC-DC converters route through a dedicated BMS. Faults on the house side are isolated here — and never propagated to the starter circuit.

BMS Protected

The result: A single drop-in battery that solves the single-battery architecture for small boats and provides a safe, fault-isolated starting circuit for larger vessels — without the load dump risk that makes LFP unsuitable for starting. This three-terminal architecture scales across the SC-31 (Group 31), SC-27 (Group 27), and SC-24 (Group 24).

Designed Around ABYC Principles
Engine starting circuit must not be interrupted by electronic devices
Overcurrent protection belongs on house circuits, not the starter feed
Alternators must always remain connected to a battery
Disconnect devices must not jeopardize the ECU or ignition system
The Chemistry

Why Sodium Ion
Was the Right Call

Sodium ion chemistry behaves almost exactly the way a marine starting battery should. It drops into existing tray sizes, works with existing alternators and charge systems, and doesn't require a complex charging infrastructure to stay safe. After years of developing sodium ion BMS design and power architecture for marine applications, this was the chemistry that checked every box.

📈
Familiar Voltage Curve

Alternators and regulators were designed around a sloped voltage profile. Sodium ion delivers that — unlike LFP's flat curve that causes overcharging and regulator confusion.

⚙️
Natural Current Limiting

Higher internal resistance naturally limits instantaneous cranking current — protecting wiring, solenoids, and alternators from the stress LFP imposes.

🌡️
No Thermal Runaway

Inherently safe chemistry. No thermal runaway risk. No special storage precautions. Safe below deck in any enclosed space.

🧊
Cold Weather Reliable

Performs well in cold conditions — exactly when you need a starting battery to work without hesitation.

🔋
Tolerates Full Discharge

Can sit at low or zero state of charge without degradation — unlike AGM, which suffers permanent damage when left discharged.

♻️
Far Greater Cycle Life

Dramatically more charge cycles than AGM. A SureCrank TRITON battery should outlast the boats most of them are installed in.

Engineering & Validation

Built On Validated Engineering

Architecture
Three-Terminal Design & Patent-Pending Protection

Three-terminal architecture fully engineered. Four-cell series configuration matches alternator and ECU voltage expectations. Patent protection filed. A custom low-current BMS handles the house-side circuit.

Chemistry
Sodium-Ion Starting Performance Validated

Cranking voltage stability, faster starts, and higher voltage under load all confirmed. The engine ECU no longer sees the sag it experienced with AGM.

Platform
One Architecture Across the Lineup

The SC-31 (Group 31) is the flagship model, with the SC-27 (Group 27) and SC-24 (Group 24) sharing the same validated three-terminal platform.

TRITON SC31 Validation Videos

TRITON SC31 Validation Videos

Lab Crank Test — 90-Second Demonstration

A controlled laboratory crank test demonstrating repeatable starting performance, stable voltage behavior, and sodium-ion reliability under standardized conditions.

Stress Test & Safety Demonstration

A high-abuse laboratory test showing TRITON SC31's thermal stability, non-combustion sodium-ion chemistry, and safe failure characteristics under extreme electrical and thermal load.

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Product Information

You'll receive technical product information and SC31 integration updates. TRITON SC31 is available for OEM and fleet evaluation.