Day: April 14, 2025

The DEKA 12-Volt 650-Amp Marine Battery is a high-performance, maintenance-free AGM battery designed for marine applications. It offers deep-cycle power, vibration resistance, and spill-proof construction, making it ideal for boats, RVs, and off-grid systems. With a 650 MCA (Marine Cranking Amps) rating, it ensures reliable starting and sustained power for electronics and trolling motors.

LiFePO4 Marine Batteries Manufacturer, Factory, OEM In China

What Are the Key Specifications of the DEKA 12V 650-Amp Marine Battery?

The DEKA 12V 650-Amp Marine Battery features AGM (Absorbent Glass Mat) technology, delivering 650 MCA and 130 minutes of reserve capacity. It operates at 12 volts, weighs 53 lbs, and has a lifespan of 4–7 years. Its sealed design prevents acid leaks, and it withstands temperatures from -40°F to 140°F, ensuring performance in extreme conditions.

This battery’s specifications make it particularly effective for marine applications where consistent power delivery is critical. The 650 MCA rating ensures quick engine starts even in cold weather, while the 130-minute reserve capacity provides sustained energy for navigation systems and onboard electronics. Compared to standard flooded batteries, the DEKA model maintains voltage stability during deep discharges, which is essential for trolling motors during extended fishing trips.

How Does AGM Technology Enhance This Marine Battery?

AGM technology uses fiberglass mats to absorb electrolyte, eliminating liquid spill risks. This design improves vibration resistance, reduces charging time by 40%, and enables a maintenance-free experience. It also allows deeper discharges (up to 80%) without damaging the battery, making it suitable for trolling motors and auxiliary marine electronics.

The AGM design’s sealed construction prevents sulfation, a common issue in traditional lead-acid batteries that reduces lifespan. This technology also enables faster recharge rates – reaching 95% capacity in under 4 hours with a proper charger. Unlike gel batteries, AGM units like the DEKA 650-Amp model perform better in high-current applications, making them ideal for powering winches or thrusters. Additionally, the low internal resistance minimizes voltage drop during peak loads, ensuring consistent performance for sensitive electronics like fishfinders and GPS systems.

Why Is the DEKA 650-Amp Battery Ideal for Marine Use?

Marine environments demand durability against moisture, vibration, and temperature swings. The DEKA battery’s corrosion-resistant terminals, rugged casing, and AGM construction ensure reliability in harsh conditions. Its dual-purpose design supports both engine starting and deep-cycle power needs, reducing the need for multiple batteries on board.

Can This Battery Be Used in Non-Marine Applications?

Yes. Its robust design makes it suitable for RVs, solar power storage, and backup systems. The deep-cycle capability powers appliances, while high cranking amps ensure reliable engine starts. However, it’s optimized for marine use, so non-marine applications may require additional ventilation or temperature controls.

How to Maintain the DEKA Marine Battery for Longevity?

Keep terminals clean and tight, store in a cool, dry place, and recharge after each use. Avoid discharging below 50% capacity. Use a compatible AGM charger to prevent overcharging. Inspect annually for physical damage or terminal corrosion. Maintenance-free design reduces but doesn’t eliminate basic care needs.

What Safety Features Does This Battery Include?

Spill-proof AGM construction, flame-retardant casing, and pressure-relief valves prevent leaks and explosions. It’s UL-certified and meets SAE/J537 standards. The sealed design minimizes hydrogen gas emissions, enhancing safety in enclosed spaces like boat cabins.

“The DEKA 650-Amp Marine Battery stands out for its hybrid design, balancing cranking power and deep-cycle endurance. Its AGM build is virtually maintenance-free, which is critical for boaters who can’t afford downtime. We recommend it for anglers and offshore enthusiasts who need reliability in unpredictable conditions.” — Redway Power Solutions Marine Division.

FAQs

How Long Does the DEKA 650-Amp Battery Last on a Single Charge?

Runtime depends on load: running a 50-amp trolling motor, it lasts ~13 hours at 50% discharge. For electronics like fishfinders (2–5 amps), it can last 60+ hours.

Is This Battery Compatible With Solar Charging Systems?

Yes. Its AGM chemistry supports solar charging. Use a charge controller to regulate input and avoid overvoltage, which can reduce lifespan.

Does the DEKA Battery Require a Special Charger?

AGM-compatible chargers are recommended. Avoid old-school chargers designed for flooded batteries, as they may overheat the cells.

A Schumacher marine battery charger enhances boating by providing reliable, efficient charging for marine batteries. Designed with waterproofing, multi-stage charging, and compatibility with various battery types, it ensures optimal performance in harsh marine environments. Its safety features, like reverse polarity protection, prevent damage, making it a trusted choice for boaters prioritizing durability and safety.

LiFePO4 Marine Batteries Manufacturer, Factory, OEM In China

What Are the Key Features of Schumacher Marine Battery Chargers?

Schumacher marine battery chargers include multi-stage charging (bulk, absorption, float), waterproof construction (IP65 rating), compatibility with AGM, gel, and lithium batteries, reverse polarity protection, and LED status indicators. These features ensure efficient charging, durability in wet conditions, and safety, making them ideal for marine applications.

Beyond core features, Schumacher chargers include temperature sensors that adjust charging rates based on ambient conditions—a critical function for boats stored in fluctuating climates. The corrosion-resistant terminals and reinforced cables withstand saltwater exposure, reducing maintenance needs. For anglers or liveaboard cruisers, these chargers provide peace of mind during extended trips where reliable power is non-negotiable.

How Do Schumacher Chargers Compare to Other Marine Battery Chargers?

Schumacher chargers outperform competitors with higher waterproof ratings, broader battery compatibility, and advanced safety mechanisms. Brands like NOCO and Battery Tender offer similar features but often lack Schumacher’s ruggedized design or multi-stage charging precision, making Schumacher a preferred choice for harsh marine environments.

While NOCO offers superior waterproofing (IP68), Schumacher balances durability with higher amperage outputs and wider compatibility. For example, its 15-amp models recharge large house batteries 50% faster than 10-amp competitors. Additionally, Schumacher’s diagnostic LEDs provide clearer status updates compared to generic indicator lights on Budget brands. This combination of power, clarity, and adaptability makes it a standout for serious boaters.

Why Is Multi-Stage Charging Critical for Marine Batteries?

Multi-stage charging prevents overcharging and sulfation by adjusting voltage/current during bulk, absorption, and float phases. This extends battery lifespan and ensures full charge capacity, crucial for marine batteries exposed to frequent deep discharges and variable weather conditions.

Can Schumacher Chargers Revive Deeply Discharged Batteries?

Yes, Schumacher’s “recovery mode” uses pulsed currents to desulfate deeply discharged batteries, restoring them to functional capacity. This feature is particularly valuable for boaters dealing with long-term battery storage or accidental discharges.

What Safety Mechanisms Are Built into Schumacher Marine Chargers?

Schumacher chargers include reverse polarity protection (prevents sparking), overcharge protection, short-circuit detection, and temperature compensation. These mechanisms safeguard both the charger and battery, reducing fire risks and equipment damage in marine settings.

How to Troubleshoot Common Schumacher Charger Issues?

Common issues include faulty connections, incorrect voltage settings, or tripped safety modes. Ensure clean terminals, verify battery type compatibility, and reset the charger. For persistent problems, consult Schumacher’s diagnostic LED codes or contact customer support.

Expert Views

“Schumacher’s engineering prioritizes resilience without compromising charging intelligence. Their IP65-rated housings and adaptive algorithms handle saltwater corrosion and voltage fluctuations common in marine environments, which many competitors overlook. For boaters, this translates to fewer dead batteries and more time on the water.” — Marine Power Systems Expert, Redway

Conclusion

Schumacher marine battery chargers combine advanced charging technology, robust safety features, and marine-specific durability. Whether maintaining batteries during off-seasons or ensuring reliable power during voyages, they offer a dependable solution for boaters seeking longevity and performance.

FAQs

Does Schumacher Offer a Warranty on Marine Chargers?

Yes, most Schumacher marine chargers come with a 2-year limited warranty, covering defects in materials or workmanship.

Are Schumacher Chargers Compatible with Lithium Batteries?

Select models support lithium batteries. Check for “LiFePO4 compatibility” in product specifications before purchasing.

How Long Does a Schumacher Charger Take to Fully Charge a Battery?

Charging time depends on battery capacity and discharge level. A 10-amp charger typically refills a 50Ah battery in 5–7 hours.

Lithium-ion deep cycle marine batteries are optimized for marine use, offering longer lifespan, higher energy density, and faster charging than lead-acid alternatives. They withstand deep discharges (up to 80-100%) without damage, are lighter, and require zero maintenance. Ideal for trolling motors, electronics, and offshore applications, they excel in reliability and performance under harsh marine conditions.

12V 100Ah LiFePO4 Lithium Battery OEM Factory

How Do Lithium-Ion Marine Batteries Differ from Lead-Acid Batteries?

Lithium-ion marine batteries provide 3-5x longer cycle life (2,000-5,000 cycles) than lead-acid, weigh 50-70% less, and deliver stable voltage under load. They charge 3x faster and allow deeper discharges (80-100% vs. 50% for lead-acid). Unlike lead-acid, they require no watering, equalizing charges, or acid spill precautions.

The structural advantages extend to installation flexibility. Lithium batteries can be mounted in any orientation without leakage risks, freeing up valuable onboard space. Their consistent power output ensures electronics like fish finders and navigation systems maintain peak performance even as battery capacity depletes. For example, a 100Ah lithium battery delivers usable capacity of 80-100Ah, versus 30-50Ah from similarly rated lead-acid batteries due to discharge limitations.

What Are the Key Safety Features of Marine Lithium Batteries?

Built-in Battery Management Systems (BMS) prevent overcharging, overheating, and short circuits. Thermal stability up to 140°F (60°C), flame-retardant casings, and sealed designs resist saltwater corrosion. Some models include Bluetooth monitoring for real-time voltage/temperature tracking and automatic load disconnection during critical failures.

Which Lithium-Ion Chemistry Is Best for Marine Applications?

Lithium Iron Phosphate (LiFePO4) dominates marine use due to superior thermal stability (no thermal runaway below 518°F/270°C) and 3,000-5,000 cycle lifespan. Nickel Manganese Cobalt (NMC) offers higher energy density for compact setups but requires stricter temperature controls. LiFePO4’s -4°F to 140°F (-20°C to 60°C) operational range suits most marine environments.

How to Properly Charge a Lithium Marine Deep Cycle Battery?

Use a lithium-specific charger with voltage limits (14.4-14.6V absorption, 13.6V float). Avoid trickle charging – lithium batteries prefer partial-state charging (30-80%) for longevity. Charge at 0.5C max (e.g., 50A for 100Ah battery). Balance cells every 20 cycles using integrated BMS. Store at 50% charge in dry, 59°F (15°C) environments during off-seasons.

What Is the True Cost Analysis of Lithium Marine Batteries?

Though 3x pricier upfront ($900-$1,500 for 100Ah), lithium lasts 8-10 years vs. 2-3 for lead-acid. Over 10 years, lithium’s cost-per-cycle is $0.15-$0.20 vs. lead-acid’s $0.50-$0.80. Factor in fuel savings from faster charging, zero maintenance costs, and no replacement purchases – ROI typically occurs within 2-4 years for frequent boaters.

Detailed cost comparisons reveal hidden savings. A 100Ah lithium battery operating at 80% depth of discharge provides equivalent usable energy to a 200Ah lead-acid bank. This reduces required battery capacity by half, offsetting initial costs. Maintenance savings average $120/year in watering systems and terminal cleaners. For charter operators, lithium’s 10-year lifespan eliminates 3-4 lead-acid replacement cycles at $400-$600 each.

Modern LiFePO4 marine batteries are revolutionising offshore power. Our 12V 200Ah model withstands 15,000 deep cycles at 100% DoD – something unimaginable with lead-acid. With CANBus integration, they communicate directly with modern outboards and chartplotters, enabling smart load prioritisation during multi-day expeditions.”

FAQ

Q: Can lithium marine batteries handle engine starting loads?

A: Yes – many lithium models now offer dual-purpose design with 800-1,200 CCA for engine starts while maintaining deep cycle capabilities.

Q: Are lithium batteries safe in saltwater environments?

A: IP67-rated units withstand temporary submersion. Stainless steel terminals and anti-corrosion coatings prevent salt damage – far safer than vented lead-acid batteries.

Q: How to winterize lithium marine batteries?

A: Store at 50% charge in dry, above-freezing locations. Unlike lead-acid, lithium won’t sulfate – 6-month storage only causes 2-3% monthly self-discharge.

Marine multi battery isolators are devices that manage multiple batteries on boats, ensuring optimal power distribution and preventing battery drain. They prioritize charging between starter and house batteries, protect against electrical faults, and extend battery life. These systems are critical for safety and efficiency in marine environments, especially during long voyages or when using auxiliary electronics.

24V 200Ah LiFePO4 Lithium Battery Factory (BCI Group 8D)

What Is the Primary Function of a Marine Multi Battery Isolator?

A marine multi battery isolator directs charging current from the alternator to multiple batteries while preventing discharge between them. This ensures that your starter battery remains reserved for engine ignition, while house batteries power appliances. It uses diodes or solenoids to create separate charging circuits, maintaining voltage stability across all batteries.

How Does a Marine Battery Isolator Differ from a Standard Battery Switch?

Unlike manual battery switches, marine isolators automate power distribution. They continuously monitor battery voltage and prioritize charging based on demand. Standard switches require manual intervention to alternate between batteries, increasing the risk of accidental discharge. Isolators also prevent backflow, ensuring depleted batteries don’t drain charged ones.

Which Types of Marine Battery Isolators Are Most Reliable?

Diode-based isolators are durable and handle high currents but cause slight voltage drop. Solenoid (relay) isolators are energy-efficient and ideal for low-power systems. Solid-state isolators, like MOSFET models, offer precision with minimal loss. For modern vessels, smart isolators with Bluetooth monitoring provide real-time diagnostics and adaptive charging.

When selecting an isolator, consider your vessel’s power demands and battery types. Diode isolators suit older boats with lead-acid batteries, while MOSFET models excel in systems requiring precision, such as lithium-ion setups. Smart isolators are ideal for tech-heavy boats with solar panels or wind turbines, as they balance charging sources automatically. Below is a comparison of key isolator types:

Why Should You Install a Multi Battery Isolator on Your Boat?

Installing an isolator prevents total power loss by isolating faulty batteries, ensures uninterrupted charging, and extends battery lifespan. It also reduces fire risks from short circuits and simplifies compliance with marine safety standards. Boats with navigation systems, refrigerators, or trolling motors benefit most from consistent power allocation.

How Can You Troubleshoot Common Marine Battery Isolator Issues?

Common issues include voltage drop (fixed by upgrading wiring), relay failure (replace solenoids), or parasitic drain (check for faulty diodes). Use a multimeter to test connectivity between batteries and alternator. Corroded terminals or loose connections often cause erratic behavior—clean with dielectric grease and ensure secure fastening.

For persistent problems, start by testing each battery individually. A sudden voltage drop in one circuit may indicate a failed diode block. If the isolator feels hot to the touch, check for overloaded circuits or mismatched battery capacities. Many modern isolators have LED status indicators – a flashing red light often signals a charging fault. Keep spare fuses and relays onboard for emergencies, especially during extended trips.

What Emerging Technologies Are Revolutionizing Marine Battery Isolation?

New lithium-compatible isolators support faster charging for LiFePO4 batteries. Solar-ready models integrate MPPT controllers for hybrid systems. AI-driven isolators analyze usage patterns to optimize charging cycles. Wireless load-sharing systems, such as CAN-bus networks, enable synchronized power management across multiple vessels in fleets.

“Modern marine isolators are no longer just fail-safes—they’re integral to energy ecosystems on boats. At Redway, we’ve seen a 40% rise in demand for smart isolators that sync with renewable sources. These systems don’t just isolate; they predict load requirements, making off-grid voyages feasible.” — Marine Systems Engineer, Redway

FAQs

Does a Battery Isolator Work with Lithium Batteries?

Yes, but only if the isolator is rated for lithium chemistry. Lithium batteries require higher charging voltages, so choose isolators with adjustable settings or models specifically designed for LiFePO4 systems.

Can I Use a Marine Isolator for Solar-Powered Systems?

Absolutely. Many isolators now include MPPT solar inputs. Ensure the unit can handle simultaneous charging from alternators and solar panels without overloading.

How Often Should I Test My Battery Isolator?

Test monthly using a multimeter to verify charging output and isolation efficiency. Before long voyages, perform a full diagnostic, including load tests on all connected batteries.

A marine battery box with a circuit breaker safeguards boat batteries from water, corrosion, and electrical faults. It combines durable, waterproof housing with a built-in circuit breaker to prevent overloads and short circuits. This system ensures reliable power for marine electronics while prioritizing safety, making it indispensable for boaters navigating harsh marine environments.

12V 100Ah LiFePO4 Lithium Battery OEM Factory

How Does a Marine Battery Box with Circuit Breaker Work?

The circuit breaker interrupts electrical flow during overloads or faults, preventing damage to the battery and connected devices. The waterproof box shields the battery from moisture, salt, and physical impacts. Together, they create a fail-safe system that maintains power stability and minimizes fire risks, even in rough conditions.

What Are the Key Features of a High-Quality Marine Battery Box?

Top-tier marine battery boxes feature corrosion-resistant materials like ABS plastic, airtight seals, and UV protection. The integrated circuit breaker should have adjustable trip settings and a manual reset function. Additional elements include ventilation ports, cable management systems, and compatibility with multiple battery types (AGM, lithium, lead-acid).

Advanced models incorporate dual-layer compression gaskets that maintain seal integrity even under extreme temperature fluctuations. UV-stabilized polymers prevent material degradation from prolonged sun exposure, a critical feature for boats without covered battery compartments. High-end circuit breakers often include arc-fault detection, which identifies dangerous sparking patterns before they escalate. For cable management, look for boxes with stainless steel clamps and dedicated routing channels that prevent chafing against sharp edges. Some premium units also feature integrated battery monitoring terminals, allowing easy voltage checks without opening the enclosure.

Which Safety Standards Govern Marine Battery Box Design?

Marine battery boxes must comply with ABYC (American Boat and Yacht Council) standards, ISO 8846 for ignition protection, and UL 1500 for electrical safety. These regulations ensure the box withstands vibration, saltwater exposure, and temperature extremes while preventing sparks or explosions in flammable environments.

Why Is Ventilation Critical in a Marine Battery Setup?

Batteries emit hydrogen gas during charging, which can accumulate explosively in enclosed spaces. Quality marine battery boxes include baffled ventilation systems to dissipate gases while blocking water ingress. This dual-action design prevents dangerous pressure buildup without compromising waterproof integrity.

Can You Install a Circuit Breaker Retroactively in Existing Battery Boxes?

Yes, marine-rated circuit breakers can be added to older battery boxes using waterproof bus bars and marine-grade wiring. However, retrofitted systems require careful ampacity matching and ABYC-compliant cable routing. For optimal safety, experts recommend upgrading to purpose-built boxes with pre-installed breakers.

How Do Marine Battery Boxes Compare to Automotive Alternatives?

Marine boxes exceed automotive versions with full waterproofing (IP67+ ratings), salt-spray-resistant materials, and ignition-protected circuit breakers. They’re engineered for constant vibration and 360° protection, unlike car battery trays designed only for splash resistance. Marine models also include tie-down systems to prevent movement in rough seas.

Marine units undergo rigorous salt fog testing equivalent to 10+ years of coastal exposure, while automotive counterparts typically only pass 500-hour humidity tests. The difference in structural integrity becomes apparent in storm conditions where marine boxes maintain seal compression during repeated wave impacts.

“Modern marine battery systems demand integrated protection. At Redway, we’ve seen a 63% reduction in electrical failures when boats switch to purpose-built boxes with marine-specific circuit breakers. The key is specifying breakers with delayed trip curves to handle starter motor surges without nuisance tripping.” — Redway Power Solutions Marine Engineer

Conclusion

A marine battery box with circuit breaker is non-negotiable for safe, reliable onboard power. By combining physical protection with smart electrical safeguards, these systems extend battery life while preventing catastrophic failures. When selecting a unit, prioritize ABYC compliance, material durability, and breaker specifications matched to your vessel’s load requirements.

FAQ

Q: How often should marine battery box seals be replaced?

A: Inspect seals annually; replace every 3-5 years or immediately if hardening/cracking appears. Saltwater exposure accelerates degradation.

Q: Can lithium batteries use standard marine battery boxes?

A: Only if the box is rated for lithium’s higher energy density. Many require additional venting and thermal runaway protection.

Q: What amp rating circuit breaker do I need?

A: Match the breaker to your battery’s maximum current output. For example, a 100Ah battery typically needs a 150-200A marine breaker.

Charging a marine battery requires verifying battery type (AGM, lithium, or flooded), cleaning terminals, and using a compatible charger. Set the charger to the correct voltage (12V/24V) and amperage (10-20% of battery capacity). Monitor temperature to avoid overheating. Disconnect once fully charged to prevent overcharging. Always prioritize ventilation and wear protective gear.

LiFePO4 Marine Batteries Manufacturer, Factory, OEM In China

How Do Charging Methods Differ Between AGM and Flooded Marine Batteries?

AGM batteries require voltage-regulated chargers (14.6-14.8V absorption phase) to avoid gas buildup, while flooded batteries need periodic equalization (15V+) to balance electrolyte levels. Flooded types demand distilled water top-offs post-charging. AGM chargers must avoid ripple voltage exceeding 5%, whereas flooded systems tolerate minor fluctuations. Incorrect methods risk sulfation (flooded) or thermal runaway (AGM).

AGM batteries excel in maintenance-free operation, making them ideal for sealed compartments. Flooded batteries, while cheaper, require monthly electrolyte checks and ventilation due to hydrogen emissions during charging. A study by Marine Battery Council showed AGM batteries retain 92% capacity after 500 cycles when charged correctly, compared to 78% for flooded types. Always match the charger’s algorithm to the battery chemistry—AGM chargers should include temperature sensors, while flooded systems benefit from manual equalization modes.

Why Is Temperature Critical During Marine Battery Charging?

High temperatures accelerate chemical reactions, risking overcharging and plate corrosion. Cold temperatures slow charge acceptance, requiring higher voltages. Smart chargers adjust voltage based on ambient readings. For example, at 32°F, lithium batteries need 0.3V higher absorption voltage than at 77°F. Always charge in shaded, dry environments to stabilize thermal conditions.

Batteries lose 20% efficiency per 15°F below 77°F. In tropical climates, limit charging to 95°F ambient—beyond this, AGM batteries may vent gas prematurely. For Arctic conditions, pre-warm lithium batteries above 14°F using insulated blankets before charging. Temperature compensation curves vary by chemistry: flooded batteries require +0.028V/°F below 77°F, while lithium needs +0.036V/°F. Install thermal probes directly on battery terminals for accurate adjustments.

Can Solar Panels Effectively Charge Marine Batteries Offshore?

Yes, 100-200W solar panels with MPPT controllers optimize energy harvest. Solar setups require deep-cycle compatibility and reverse polarity protection. For lithium batteries, ensure panels deliver 14.4-14.6V absorption voltage. Key limitations include inconsistent sunlight and shading—supplement with backup generators or dual battery banks for uninterrupted power during overcast days.

What Are the Risks of Using Automotive Chargers for Marine Batteries?

Automotive chargers lack marine-specific safeguards like spark-proof circuitry and humidity resistance. They may overcharge deep-cycle batteries due to improper float voltage settings (13.2V vs. 13.8V for marine). Rapid charging modes can warp lead plates in flooded batteries. Always use marine-certified chargers with ABYC-compliant safety features.

How to Troubleshoot a Marine Battery That Won’t Hold a Charge?

Test voltage (below 12.4V indicates issues) and specific gravity (1.225-1.265 range). Check for sulfation (white residue on terminals) or corroded cables. Load-test to identify weak cells. If voltage drops ≥0.5V under load, replace the battery. For lithium types, BMS faults or cell imbalances often require professional recalibration.

Expert Views

“Marine batteries demand precision—voltage spikes as small as 0.5V can halve lithium battery cycles. Redway’s 2023 study showed 68% of AGM failures stem from improper float charging. Always use temperature-compensated chargers and avoid ‘set-and-forget’ practices in saltwater environments.” — Redway Power Systems Engineer.

Conclusion

Optimal marine battery charging combines correct equipment, environmental awareness, and proactive maintenance. Prioritize manufacturer guidelines, invest in smart chargers, and monitor performance metrics to extend lifespan and ensure reliability during maritime operations.

FAQ

How long does a marine battery take to charge?

Charging time depends on capacity: a 100Ah battery at 10A takes 10 hours. Lithium batteries charge 2x faster than AGM/flooded types.

Can I charge a marine battery overnight?

Only with chargers featuring auto-shutoff and float modes. Continuous charging beyond 14.4V degrades all battery types.

Should I remove marine batteries for winter storage?

Yes. Store at 50-80% charge in frost-free areas. For lithium, maintain 30-60% charge to avoid BMS drain.